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Consumption of insects has gained interest because it may provide a more sustainable and healthier alternative for conventional meat. However, in Western societies, insect consumption is met with resistance due to negative attitudes based on fear and disgust. To further understand consumers' willingness to try insect meat, a 2 (meat type: bovine vs. insect) × 2 (product type: common vs. uncommon) experiment was conducted (n = 130). Four food choice factors were expected to mediate the effect of meat type and product type on willingness to try: health, sensory appeal, risk perception, and disgust. Results indicate that meat type had no effect on willingness to try. Relative to bovine meat, insect meat was perceived as both healthier and more disgusting, which could explain the absence of a meat type effect. Unexpectedly, use of insects in common products (burgers) as compared to uncommon products (skewers) was met with a lower willingness to try. Also, common products with insect meat was considered to be less healthy and more disgusting, compared to uncommon products with insect meat.
The cigarette beetle, Lasioderma serricorne (F.) (Coleoptera: Anobiidae), is an important pest in the food and tobacco industry in many regions of the world. Despite a great deal of research, control of this pest still relies on the use of phosphine fumigation, which is becoming less effective as the insect develops resistance to this compound. In addition, series of other nonchemical methods used to control the insect have given mixed and irregular results. This review summarizes and discusses information on important aspects of the biology and ecology of the cigarette beetle, and its control. The topics covered include a taxonomic discussion of the cigarette beetle, which includes a discussion of other anobiid species of economic importance. The mating behavior of the insect and conditions favorable for pest development were described. The review also includes a discussion of the life stages of the insect, its feeding habit, and economic damage. Important aspects of its chemical ecology and a discussion on the association between this species and its microorganisms, and major natural enemies, were presented. A summary of its flight behavior, including the factors governing flight initiation and temporal and seasonal flight activity were reviewed. Finally, the control methods currently used in the management of the insect were described. The review also identifies potential areas of further research on L. serricorne and gives an analysis of the control methods worthy of further investigation in the search for practical and sustainable methods for the management of this pest.
Remote sensing (RS) and geographical information system (GIS) technology have seldom been used in apiculture. We applied these tools to map the optimum honey bee colony carrying capacity and estimate honey production during the honey flow of ‘Talh’ trees (Acacia gerrardii Benth. [Fabaceae: Mimosoideae]) in the Rawdat-Khuraim oasis, central Saudi Arabia . A SPOT 5 panchromatic image (2.5-m resolution) was used to delineate the distribution ofTalh trees. ArcGIS was used in image processing and data management, analysis, and visualization. The outputs were maps of Talh distribution, an optimum spatiotemporal beekeeping plan, and predicted potential honey yield. Each Talh tree was predicted to produce a theoretical maximum of 8.5-kg Talh honey per season. Under the current nonoptimum distribution of apiaries, Rawdat-Khuraim produces 4,876-kg honey per season. Optimally, it should produce 9,619-kg honey per season from 1,278 colonies distributed in 12 beekeeping sites.This study provides a technical approach for the use of RS and GIS in describing, planning, and managing honey flows and predicting honey harvest through a spatiotemporal workflow.
Honey bee (Apis mellifera) (Linnaeus) (Hymenoptera: Apidae) queens, the reproductive female caste, are crucial for colony success, and many management problems that beekeepers face are related to their diminished reproductive quality and premature failure. Previous research has suggested that temperature extremes may affect the viability of stored sperm in queens' spermathecae, thus the abiotic conditions of queens during transport may be germane to these problems. We recorded the temperatures experienced by queens during 2 yr of package transportation and tracked the newly installed colonies through establishment and buildup. During this critical 6–8 wk period, we observed typically high rates of queen failure (~25%) but found no indication that these postinstallation queen events were driven by temperature-related damage to stored sperm (an essential component of queen quality) incurred during transportation. We also found no indication of significant hot or cold zones across the truckloads of packages that would suggest a problem in how packages are insulated during transportation. However, we did observe significantly higher temperatures (31.2 vs. 29.9°C) and lower temperature variance (8.8 vs. 12.2) in queens that ultimately failed during the observation period, indicating that workers may respond differently to these queens in a way that manifests as more insulating clusters around queen cages. If so, then the collective process by which workers accept or reject a foreign queen may already be detectable even if it does not ultimately conclude until some weeks later. Nevertheless, it remains unclear why large numbers of otherwise high-quality queens are failing in newly installed packages.
Pyrifluquinazon (PQZ) is an Insecticide Resistance Action Committee (IRAC) Group 9 insecticide that has recently been registered for use in the United States for control of soft-bodied sucking insect pests. Although it has been classified as practically nontoxic to honey bees, Apis mellifera L. (Hymenoptera: Apidae), based on acute contact bioassays, additional information on sublethal effects of this insecticide on honey bees is lacking. Using a combination of laboratory assays with video movement tracking software and near-field evaluations of colonies foraging in a high-tunnel experiment, we determined that, when fed PQZ at a concentration of 84 mg active ingredient (ai)/liter (= ppm) in sugar water, a reduction in overall movement by the foraging worker bees was observed. However, when provided with honey reserves in the hive, honey bees rejected the PQZ-treated sugar water. These results indicate that, if ingested at levels of 84 mg ai/liter, PQZ could have a negative effect on honey bee behavior; however, honey bee workers appear to be able to detect the presence of PQZ in their food and reject it.
For more than four decades, the presence of the whitefly Bemisia tabaci Gennadius complex as a pest and transmitter of begomoviral diseases has been one of the most important phytopathological events in cultivated species worldwide. In addition, the number of whitefly species, as well as the viruses they transmit, has been increasing over time. In the state of Baja California Sur (BCS), Mexico, the diversity of B. tabaci has been delimited to MEAM1 and NW species, affecting mainly tomato, pepper, and squash. However, the relationship of these species with the dispersion of the begomoviruses previously detected in the study area is still unknown. In a 5-yr study (2012–2016), these species of whiteflies and begomoviruses were identified. Moreover, the recurrence, seasonal distribution, and impact they have on the spread of the begomoviral diseases were assessed. The identification of whiteflies was done targeting the mtCOI by PCR-DNA barcoding assay. For begomoviruses identification, a set of degenerate and specific primers targeting the IR region and CP gene were used. To determine seasonal abundance, monitoring was performed every 15 d by means of yellow traps. The MEAM1 species in all localities was observed with the highest peak population (>10 whiteflies/trap) from March to April. The guidelines for naming begomovirus species for the International Committee on Taxonomy of Viruses (ICTV) establish that the names when they are preceded by the acronym the whole name is in lowercase, not italicized (e.g. bean golden mosaic virus (BGMV)); when the name goes alone without the acronym then its capitalizes the first letter (e.g. Bean golden mosaic virus) and when these are referred to in a taxonomic sense they are italicized and the first letter is capitalized (e.g. Bean golden mosaic virus). This study provides details of the distribution and occurrence of MEAM1 species and diversity of begomoviruses that could be useful in disease management in BCS and worldwide.
The effects of fluctuating and constant temperatures on the development and longevity of Diaphorencyrtus aligarhensis (Shafee, Alam, and Argarwal) (Hymenoptera: Encyrtidae), a parasitoid sourced from Pakistan and released in California for the classical biological control of Diaphorina citri Kuwayama (Hemiptera: Liviidae), were examined. The influence of six fluctuating temperatures that averaged 15, 20, 25, 30, 32, and 35°C, over 24 h on the development times and longevity of male and female D. aligarhensis were quantified and compared to six constant temperatures set at the same average temperatures. The development rates of immature stages of D. aligarhensis as a function of temperature were modeled using one linear and four nonlinear models. Fluctuating temperatures had significant effects on parasitoid development times and longevity which differed across experimental temperatures. Degree-days required for completion of cumulative development of D. aligarhensis were significantly different being 21% lower under fluctuating temperature regimens when compared with constant temperatures. The lower temperature threshold estimates above which development occurred were estimated to be lower under constant than fluctuating temperatures. The estimated values of upper and optimum temperature limits were similar for individuals reared under constant and fluctuating temperatures. Diaphorencyrtus aligarhensis lived longer at constant intermediate temperatures and for shorter times at constant lower temperature extremes when compared with their fluctuating temperature counterparts. Daily thermal fluctuations significantly influenced life history parameters of D. aligarhensis and should be considered when assessing likelihoods of establishment and impacts of this parasitoid on D. citri across diverse citrus-growing climates.
The predacious midge, Aphidoletes aphidimyza (Rondani), is an effective exclusive natural enemy of aphids in greenhouses and field crops. In this study, prey preference of A. aphidimyza was determined using seven treatments including different stages (third-instar nymphs and adults) of two prey species (Aphis gossypii Glover and Myzus persicae (Sulzer)) based on Manly's β preference index. Results of experiments consisting of two different preys showed that A. aphidimyza larvae consumed A. gossypii more than M. persicae, and the third nymphal stage of both species was preferred more, compared with adults. When all four types of prey were studied, Manly's index was 0.379, 0.235, 0.208, and 0.176 for nymphs of A. gossypii and M. persicae and adults of A. gossypii and M. persicae, respectively. Therefore, the nymphs of both species, as the most preferred prey, were used to study the reproductive performance of the predator in microcosm conditions. The significantly longer adult longevity (female: 7.62 ± 0.15, male: 7.42 ± 0.23 d), higher fecundity (93.75 ± 2.94 offspring per female), and higher intrinsic rate of increase (0.175 ± 0.009 d-1) of A. aphidimyza were obtained, while consuming third-instar nymphs of A. gossypii. Finally, this study indicated that third-instar nymphs of A. gossypii are the most suitable food for mass rearing of A. aphidimyza.
Understanding the effects of diet on metabolic events is crucial for biological control programs of parasitoid insects. As bioindicators of long-term physiological stress: survivorship of fifth instar larvae, pupation, adult survival, and developmental time for stages of endoparasitoid Pimpla turionellae L. (Hymenoptera: Ichneumonidae) were investigated by rearing the parasitoid on the host, Galleria mellonella L. (Lepidoptera: Pyralidae) pupae were treated with neomycin. First instar larvae of G. mellonella were reared on artificial diets containing 0.005, 0.01, or 0.5 g neomycin (g/100 g of diet) until seventh instar larvae; the pupae from these larvae were used as a host for rearing P. turionellae. In the control group, the pupae from larvae reared on artificial diets without neomycin were used as a host. Survivorship of fifth instar, pupal, and adult stages of P. turionellae L. reared on G. mellonella pupae as a host fed with different concentrations of neomycin were significantly decreased in comparison to the control group. Approximately eighty percent of P. turionellae L. pupae were produced from control host pupae, while other neomycin concentrations significantly decreased the pupation of the parasitoid. Pimpla turionellae L. larvae reared on control host pupae reached fifth instar in about 9.6 ± 0.61 d, while the larvae reared from a host pupae exposed to the highest antibiotic concentration completed their development to the fifth instar in about 7.4 d. These results showed that neomycin, and possibly its metabolites, contaminated P. turionellae L. larvae from a host and affected larval stages of the parasitoid.
Sóstenez A. Vessaro-Silva, Marcílio Hubner Miranda Neto, Rose Meire Costa Brancalhão, Lucineia Fátima Chasko Ribeiro, Ana Tereza Bittencout Guimarães, Camila Maria Toigo de Oliveira
Bombyx mori nucleopolyhedrovirus (BmNPV) is a DNA virus that infects different tissues in Bombyx mori at immature stage. Caterpillars become infected after ingesting polyhedral occlusion bodies (POB) present in contaminated mulberry leaves and spread through the body after passing the epithelium of the midgut. As this organ is responsible for digestion, most absorption of nutrients requires an intact epithelium to maintain gastrointestinal physiology. Considering the importance of this organ in the feeding of caterpillars and in the production of quality silk threads, and because it is also the first barrier faced by the BmNPV, the study analyzed details of cytopathological events in the intestinal cells as well as evaluated the action of the antioxidant systems as a response to cellular infection. For this purpose, B. mori hybrid caterpillars of fifth instar were inoculated with a suspension of 7.8 × 107 POB ml-1 and, from the first to the eighth day post-inoculation (dpi), segments of the midgut were collected and processed for light and electronic microscopy. The nuclei of columnar cells showed polyhedric occlusion bodies in the seventh dpi and fragmentation of those cells, with peritrophic matrix disorganization. Analysis of antioxidant systems shows some moments of changes of the catalase enzymes and superoxide dismutase. Analysis of the cholinergic system revealed changes only at the beginning of the infection. Thus, the article acknowledges the antioxidant system as a barrier to stop viral infection, albeit it cannot stop infection from occurring, once a coevolutionary bond is maintained between virus and host.
Horizontal transmission of Helicoverpa armigera nucleopolyhedrovirus (HearNPV) has been found to occur through several pathways involving abiotic factors such as soil, wind, and rain, and biotic factors such as predators, parasitoids, and infected hosts. Previous studies examining horizontal transmission through certain biological carriers speculated they were likely not significant in increasing infection rates, however; these studies only focused on a relatively small number of arthropods present within a field setting. This study was conducted to evaluate the horizontal transmission potential of HearNPV by all potential biological carriers when applied as a foliar bioinsecticide or as virus-infected, nonmotile Helicoverpa zea (Boddie) (Lepidoptera: Noctuidae) larvae in a soybean field. Soybean plots were either sprayed with HearNPV or infested with late-stage HearNPV-infected larvae, and sample zones were sampled 3, 7, 10, 14, 17, and 21 days after the infestation, and analyzed for viral presence using PCR. We then identified HearNPV carriers through contamination from the application (involuntary) or through contact with a HearNPV-infected larva (voluntary). Both were confirmed through PCR analysis. Regardless of application technique, on average, HearNPV was capable of disseminating up to 61.0 m in 3 d after inoculation and was found within the sampled canopy 13–21 d after inoculation. Several arthropods were identified as novel carriers of HearNPV. Results from this study indicate that many novel HearNPV carriers are likely important in disseminating HearNPV.
Lysiphlebus confusus Tremblay and Eady, L. fabarum (Marshall), and L. testaceipes (Cresson) (Hymenoptera: Braconidae: Aphidiinae) are important biological control agents for aphids. To select the appropriate biological control agent for a target pest, an understanding of the demographic parameters is essential. Therefore, a study was conducted to determine the effect of five temperatures, 12, 17, 22, 27, and 32°C, at 60% RH and 5.0 Lux photoperiod of 16:8 (L:D) h, on the parasitism rate, development, and fecundity of these three parasitoids of Aphis gossypii Glover (Hemiptera: Aphididae). Only L. fabarum parasitized at 12°C and the rate was low. None of the parasitoids was able to develop at 32°C. Lysiphlebus testaceipes had the shortest developmental period at the other temperatures. Lysiphlebus confusus and L. fabarum had similar developmental times at 22 and 27°C, with L. confusus completing its development faster at 17°C. The mortality rate of the three parasitoids varied between 3 and 20% at 17, 22, and 27°C, except for L. testaceipes which had about 53% mortality at 27°C. Lysiphlebus testaceipes had the highest net reproductive rate at all temperatures for the 2.5 and 97.5% bootstrap CIs. Lysiphlebus fabarum had the highest intrinsic rate of increase at 22°C and L. testaceipes had the highest at the other temperatures. The best temperatures for fecundity were 17 and 22°C for L. testaceipes and 22°C for the other species. Lysiphlebus testaceipes appeared to be the most suited biological control agent for A. gossypii in southern Turkey, but its intolerance to high temperature could prove problematic for its establishment and persistence in this region.
Mass rearing fruit flies of the genus Anastrepha for the sterile insect technique involves the use of artificial larval diets that commonly contain corn cob powder as a bulking agent. Corn cob powder varies in quality, and larval diets that contain it can be reaching at high temperatures (>34°C), which subsequently has a negative effect on pupal weight and adult survival. In addition, corn cob powder is susceptible to contamination by mycotoxins, which can inhibit larval development and cause high larval mortality. The objective of this work was to develop a low-cost artificial larval diet for mass rearing Anastrepha spp. fruit flies using coconut fiber, a nonconventional bulking agent, and to evaluate its effects on the quality parameters for A. ludens wild-type, A. ludensTap-7 GS-strain, A. obliqua, A. serpentina, and A. striata.The coconut fiber diet resulted in an increase in the larval and pupal weight of A. ludens Tap-7 GS-strain and A. obliqua, an increase in the larval weight of A. ludens wild-type, an increase in the flight ability of A. obliqua and A. serpentina and an increase in adult eclosion in A. ludensTap-7 GS-strain. The coconut fiber diet resulted in increased production and quality of the mass-reared flies, reduced the cost of the diet by 15 and 20% for A. ludens and A. obliqua, respectively, and led to further cost savings through reduced labor processes.
Alligatorweed, Alternanthera philoxeroide (Mart.) Griseb. (Amaranthaceae) is an invasive weed in China that is often kept under control by the alligatorweed flea beetle, Agasicles hygrophila Selman and Vogt (Coleoptera: Chrysomelidae) introduced into China from Argentina in the 1980s. Elevated CO2 levels have been shown to have a direct effect on Ag. hygrophila. In order to fully evaluate the indirect effects of three different atmospheric concentrations of CO2 (420, 550, and 750 ppm) on the population parameters of Ag. hygrophila reared on Al. philoxeroides, we collected life table data for Ag. hygrophila using the age-stage, two-sex life table method. In general, there were no significant differences in the lengths of the preadult parameters among the three treatments. The adult duration and total longevity of males, however, did increase as CO2 increased in concentration. Although the adult preoviposition and total preoviposition periods decreased, the fecundity, oviposition days, eggs per oviposition day, net reproductive rate, intrinsic rate of increase, and finite rate of increase all increased significantly at the high CO2 concentration. Consequently, we determined that the Ag. hygrophila population size will potentially increase rapidly over a short period of time at elevated CO2 concentrations. Our results suggest that 550 and 750 ppm CO2 may also cause physiological changes in Al. philoxeroides that, in turn, provide enhanced nutrition for increasing reproduction in Ag. hygrophila by accelerating maturation of their reproductive system. These results indicate that the efficacy of Ag. hygrophila as a biological control agent against Al. philoxeroides will likely be increased at 550 and 750 ppm CO2.
Larvae of Prionus californicus Motschulsky feed on the roots of many woody perennial plants and are economically important pests of hop Humulus lupulus L. (Urticales: Cannabaceae) and sweet cherry Prunus avium (L.) (Magnoliopsida: Rosaceae) in the United States Pacific Northwest and Intermountain West. Adult males are strongly attracted to a volatile sex pheromone, (3R,5S)-3,5-dimethyldodecanoic acid, produced by females. Here, we summarize the results of field experiments evaluating the synthetic pheromone in a blend of all four possible stereoisomers as a means for managing P. californicus in hop yards and sweet cherry orchards by mating disruption (MD). Mean capture of male beetles was lower, in all 3 yr of the study, from plots in commercial hop yards and sweet cherry orchards treated with synthetic P. californicus pheromone than from similar, untreated plots. Although trap catch was lower in sweet cherry, relative differences between trap catches from MD and nonmating disruption plots were similar to that seen in hop yards. The number of P. californicus larvae recovered from plots in hop yards treated for three consecutive growing seasons with synthetic pheromone was lower than in similar plots that were not treated with the pheromone or treated with the soil fumigant ethoprop. Our research demonstrates that deployment of synthetic P. californicus pheromone effectively reduces mate-finding by males, can effectively reduce larvae populations in pheromone-treated hop yards, and thus, has excellent potential for managing P. californicus in hop, sweet cherry, and perhaps in other crops where it or Prionus species are pests.
The three-cornered alfalfa hopper, Spissistilus festinus (Say) was shown to transmit Grapevine red blotch virus (GRBV) in a greenhouse study. GRBV is the causal agent of Grapevine Red Blotch Disease, which reduces the quality of wine produced from infected grapes. Due to the general lack of prior concern regarding S. festinus on grapevines, the biology of this species in vineyards has been largely unknown. A 2-yr study with weekly sampling was conducted in a Californian vineyard to increase the knowledge of S. festinus seasonal dynamics and distribution. The overwintering S. festinus adults were first captured in the vineyard before bud break. Detection of late-instar S. festinus nymphs, the first in-field adult generation, and grape anthesis occurred concurrently in 2016 and 2017. Two in-field S. festinus generations were documented by peaks in sweep net sampling of vineyard groundcover in 2016, whereas only one generation was observed in 2017. There appears to be an inverse relationship between the number of S. festinus adults sampled on ground cover and the number of girdles in the grapevine canopy. Spissistilus festinus exhibited an aggregated distribution in the vineyard and a significant edge effect. Results from this study will contribute to the development of sampling and management guidelines and determine timing of control measures to reduce populations of S. festinus within vineyards to minimize the virus spread.
For insects, female density is closely related to reproductive output. However, little is known about the effects of female density on male mating and female postmating performances. Here, we explored the effects of female density in cotton mealybug, Phenacoccus solenopsisTinsley (Hemiptera: Pseudococcidae), an invasive, rapidly spreading pest in Asia damaging multiple crops and horticultural plants. Using USB digital microscopes, we investigated the frequency, duration, and intervals of mating for males that were individually supplied with 1, 5, 10, and 15 females. We also evaluated the reproduction of mated females and the sex ratio of their offspring. As the female density increased, males mated with more females while substantially shortening mating intervals. Mating occurred actively at the densities of 10 and 15 females, where males mated four times on average, and some mated 6–9 times. However, mating duration and the observed reproductive parameters of females (preoviposition period, overall period from formation of ovisacs to female death, fecundity, and offspring sex ratio) did not differ significantly with female density. A weak trade-off existed between males' mating frequency and longevity, but there was no relationship between females' fecundity and longevity. In conclusion, despite their short lifespan, P. solenopsis males have a high mating capacity, and their mating frequency and intervals can be significantly affected by female density. In contrast, female density has little influence on females' postmating performance. Our findings indicate the significance of the reproductive biology and life history strategies for rapid establishment and population development of mealybugs in newly invaded regions.
Blueberry gall midge, Dasineura oxycoccana (Johnson) (Diptera: Cecidomyiidae), is an emerging pest on wild blueberry, Vaccinium angustifolium Aiton (Ericales: Ericaceae). The purpose of this study was to document the population increase of blueberry gall midge on this crop in Maine since its discovery in 2003 until 2018. Dasineura oxycoccana appears to have three generations during the prune cycle in Maine wild blueberry, although this may vary among years. Prune fields have higher infestation rates than crop fields, most likely due to the greater abundance of susceptible leaf tissue. Production system does affect infestation rates. Fields managed under a high input system exhibit lower gall midge infestation than low or medium input fields. Field infestation rates in organic fields were intermediate to high input and low and medium input fields. In seven trials conducted between 2010 and 2017, D. oxycoccana infestation of stems resulted in significantly fewer flower-bud clusters developed at the end of the prune year in four of seven trials and significantly fewer viable flowers during bloom in the crop year in four of seven trials. Two of the seven trials resulted in significantly more flowers on infested stems than noninfested stems, evidence that in some years D. oxycoccana infestation may stimulate flower-bud production, resulting in an increase in potential yield. We provide an optimal sampling plan for D. oxycoccana infestation sampling and economic thresholds for three levels of production (yield levels) and three expected prices that growers might receive.
The lower developmental threshold (LDT) and the number of developmental degree days (DDs) are fundamental parameters used to build phenology models that can be used to predict the timing of biological events during insect development. The Chinese citrus fly, Bactrocera minax (Enderlein) (Diptera: Tephritidae) is one of the most destructive citrus pest in China and Bhutan. This species overwinters as diapausing pupae in the soil before emerging as adults in the spring. In this study, B. minax collected from three representative geographical populations in China (Guizhou, Hubei, and Shaanxi) was used to conduct LDT experiments under laboratory conditions. Emergence data collected from pupae exposed to 10 constant temperatures was used to estimate the LDT and DDs required to complete pupal development for the three populations. The results show that LDT and DDs values for the Hubei and Shaanxi population are 11.9°C, 447.3 DDs and 11.5°C, 511.3 DDs, respectively. However, the geographic variation in pupal developmental rates was not statistically significant between the two populations. In addition, the Guizhou population was identified as a mixture of B. minax and B. tsuneonis (Miyake). The LDT and DDs values for the Hubei and Shaanxi populations obtained in this study can be used to predict adult emergence of naturally occurring field populations of B. minax within the majority of the citrus-growing production areas of China. These data can also be used in models to predict the risk of establishment of this species in the United States or other citrus-growing regions.
Management of Diaphorina citri Kuwayama (Hemiptera: Liviidae) populations is one of the major strategies for reducing the spread and incidence of huanglongbing (HLB). HLB is putatively caused by Candidatus Liberibacter spp. (Rhizobiales: Phyllopbacteriaceae) that are transmitted to citrus by psyllid vectors. Diaphorina citri population monitoring is done to detect its presence and inform on management decisions. Various methods are used for detecting and estimating D. citri densities but trapping with yellow or lime-green sticky cards has proven to be the most effective method. These sticky cards rely on the color preference of adult D. citri, but many flying organisms are attracted to the same color spectrum as psyllids. Hence, in field situations, sticky traps are hampered by large numbers of bycatches of nontarget organisms and debris. Here, we described a method using a mesh laid on the surface of traps as a sift to catch mainly psyllids, while reducing bycatches. By filtering D. citri through this mesh, they can be counted more rapidly and accurately. Although mesh-covered traps captured 5–15% less D. citri relative to uncovered ACP traps, both types of traps statistically agreed on D. citri detection and population densities. The effectiveness of mesh-covered traps did not vary with season. In addition, mesh-covered traps eliminated >90% of nontarget organisms and allowed for quicker enumeration of D. citri. We expect this method will become an important component of redesigning integrated pest management programs in citrus groves by reducing unintended impacts of beneficial arthropods during large scale D. citri monitoring.
Flavonoids are secondary metabolites that help plants resist insect attack, but pest insects have evolved enzymes that reduce the toxicity of these secondary metabolites. We studied the response of the grasshopper Oedaleus asiaticus Bey-Bienko fed different concentrations of quercetin, a representative flavonoid. Oedaleus asiaticus growth (survival rate and growth rate) was significantly reduced at high quercetin concentrations. Reactive oxygen species (ROS) increased significantly in response to the diet stress associated with high quercetin concentrations. Gene expression and protein phosphorylation level of the IGF→FOXO cascade related to the stress response in the O. asiaticus insulin-like signaling pathway (ILP) were also reduced. Multiple protective enzyme activities were regulated by FOXO. Mixed-function oxidase (MFO), superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT), were all significantly increased with exposure to high quercetin concentrations. Quercetin negatively regulated the ILP pathway, and was detrimental to O. asiaticus growth and survival, as more energy was required for detoxification. This study showed how flavonoids impact on O. asiaticus biochemical pathways, physiology, and development. Flavonoids offer a new option for the development of biological pesticides for application to grasshopper biological control.
Lacewings (Neuroptera: Chrysopidae) are part of the beneficial fauna found in citrus orchards under both organic and conventional pest management. Due to their importance, knowledge about susceptibility of these predators to insecticides is a key element for their use as biological control agents. We studied the inter- and intraspecific susceptibility of the following lacewing species to bifenthrin, chlorpyrifos, and imidacloprid: Ceraeochrysa cincta (Schneider) (Neuroptera: Chrysopidae), Ceraeochrysa cubana (Hagen), Ceraeochrysa paraguaria (Navás), and Chrysoperla externa (Hagen). Different concentrations of these insecticides were sprayed on first instar larvae of these lacewing species from six orchards (three organic and three conventional), and LC50s were estimated. Development and reproduction of the most common lacewing, C. cincta, from both organic and conventional management systems were also studied. Lacewings from conventional management areas do not always have greater tolerance to insecticides. Chrysoperla externa was the most susceptible species to insecticides. Ceraeochrysa cincta displayed the highest LC50 and its populations from the conventional system showed lower egg hatching but shorter egg and larval developmental time. Adults collected from orchards managed conventionally lived longer, exhibited a higher population growth rate and a reduced doubling time. Ceraeochrysa cincta was the more tolerant species to insecticides better coping with systems that rely on chemical control as the main pest management tactic used.
Western corn rootworm (Diabrotica virgifera virgifera LeConte) presents significant pest management challenges for farmers in both North America and Europe. IPD072Aa, a protein derived from Pseudomonas chlororaphis, has previously been shown to have activity against western corn rootworm. In the current study, the spectrum of activity of IPD072Aa was evaluated in controlled laboratory diet bioassays. IPD072Aa was fed at high concentrations in subchronic or chronic bioassays to 11 different insect species, representing 4 families within Coleoptera, and an additional 4 species representing four families of Lepidoptera. No adverse effects were noted in the Lepidoptera species. Within the order Coleoptera, western corn rootworm was the most sensitive species tested. A range of responses was observed within each of the four families of Coleoptera evaluated that included either no-observed effects or reduced growth, developmental delays, and/or reduced survival. These data will help inform the environmental risk assessment of genetically modified plants that express the IPD072Aa protein for western corn rootworm control.
Drosophila suzukii (Matsumura) is an important pest of small fruits, which has been causing significant damage to commercial crops in North America, Europe, and South America. This pest is mainly controlled with insecticide applications because of its highly biotic potential and polyphagy. However, studies conducted in crops infested by D. suzukii have shown that this species is attacked by parasitoids that may serve as effective biological controls for this pest. The aim of the current study is to assess the lethal time (LT10 and LT50) and parasitism potential of exposed adults (F0): sex ratio and longevity (F1) of Trichopria anastrephae Lima and Pachycrepoideus vindemmiae (Rondani) when exposed to dry residues of different commercial insecticides. Abamectin, acetamiprid, thiamethoxam, malathion, phosmet, deltamethrin, spinetoram, and spinosad were evaluated. Pachycrepoideus vindemmiae was more sensitive to insecticides than T. anastrephae, showing higher mortality rates in a shorter period of time, as well as a significant reduction in parasitism. Spinosyns (spinosad and spinetoram) and abamectin caused high P. vindemmiae mortality rates, but were harmless to T. anastrephae. Neonicotinoids, organophosphates, and pyrethroids caused high mortality rates regardless of the species. Treatments did not affect D. suzukii offspring longevity and sex ratio (F1). The current study provides information needed for the implementation of D. suzukii management programs focused on the conservation of natural enemies.
Economically damaging infestations of Lygus lineolaris (Palisot de Beauvois) (Hemiptera: Miridae), the tarnished plant bug, have been increasing in North Carolina and Virginia cotton since 2009. We conducted experiments to compare prophylactically timed sprays based on cotton phenology and current action thresholds based on sweep net and drop cloth sampling. In the second year of the study, we included planting date as a factor, with early and late-planted cotton. We found L. lineolaris nymph densities were reduced by at least 60% in North Carolina and 74% in Virginia in threshold plots when compared with the untreated control. Protecting the crop from first square through the fourth week of bloom afforded at least 30% control across planting dates in Virginia and at least 40% control in North Carolina. Economic returns were two to three times greater in early-planted cotton than in late-planted cotton.Treating cotton at action threshold or using prophylactic sprays from first square until the sixth week of bloom in early-planted cotton yielded over $500/ha in net returns in both North Carolina and Virginia. This study supports previous research that shows controlling L. lineolaris infestations during squaring and early weeks of flowering is critical for maximizing yield potential. Our findings also suggest that prebloom and bloom thresholds based on adult and nymphal density devised in the Mid-South may need revision in North Carolina and Virginia.
The English grain aphid, Sitobion avenae (Fabricius), is a cosmopolitan insect pest on cereals. Many studies on life-history traits indicate that S. avenae clones from different areas have diverged on various host plants. However, direct genetic evidence for this phenomenon is rare. Thus, S. avenae clones were collected from barley (Hordeum vulgare L.) and wheat (Triticum aestivum L.) in four provinces (i.e., Hubei, Henan, Jiangsu, and Zhejiang) of China, and characterized using six microsatellite markers. In total, 92 multilocus genotypes were found from 302 individuals of S. avenae. Population Jiangsu was found to have relatively high levels of genotypic diversity among the four geographical populations. Substantial long-distance migration of S. avenae was found from Zhejiang to the other three provinces. Thus, relatively low genetic differentiation was found between these geographic populations. Barley clones of S. avenae showed higher gene diversity compared with wheat clones. The gene flow from barley to wheat clones appeared to be more likely than that in the reverse direction. Diversity indices and structure for S. avenae clones suggested highest level of genetic divergence between barley and wheat clones in Jiangsu among all sampling locations. Besides Jiangsu, pairwise FST values indicated moderate levels of genetic divergence between barley and wheat clones in Zhejiang. Thus, compared with geographical factors, plant factors could be relatively more important in promoting genetic differentiation in S. avenae. Our results provide insights into genetic differentiation of S. avenae on different plants, as well as a basis for exploring the molecular mechanism for its differentiation on plants and biotype development.
Whole-plant cage field experiments were conducted in 2014, 2015, and 2016 to characterize cotton injury from a species complex of boll-feeding sucking bugs represented by the verde plant bug, Creontiades signatus (Distant) (Hemiptera: Miridae), brown stink bug, Euschistus servus (Say), green stink bug, Acrosternum hilare (Say), and redbanded stink bug, Piezodorus guildinii (Westwood) (Hemiptera: Pentatomidae). Field-collected adult bugs were used to infest cotton plants previously maintained free of insect injury. Plants caged in groups of four were infested at mid-bloom and late-bloom for 7 d with four insect densities: 0 (control), 0.25 bugs per plant, 1 bug per plant, and 2 bugs per plant. Species and water stress conditions varied across years, allowing selective within-year comparisons. Response to feeding resulted in boll injury in the form of lint deterioration and cotton boll rot at mid- and late-bloom stages, and in water limiting and non-water limiting conditions. Although plant injury was apparent across a wide range of conditions, subsequent yield decline attributed to insect feeding was seen primarily under water limiting conditions when plants were infested at mid-bloom. For these conditions, significant yield—insect density relationships were used to calculate economic injury levels (EILs) for each species. EILs expressed as bugs per plant from lowest to highest were the brown stink bug (0.29–0.31 bugs per plant), redbanded stink bug (0.33), verde plant bug (0.49), and green stink bug (0.50). Given the variability observed among species, species-specific EILs may be used where the injurious species is known and combined for stink bugs (a common EIL of 0.34 bugs per plant) where multiple species occur. Verde plant bug was less damaging and can be considered separately, but its EIL was generally within a range of values for the boll-feeders encountered.
In some Bt cotton (Gossypium hirsutum L.) varieties, bollworm (Helicoverpa zea Boddie) larval behavior differs from non-Bt varieties. Laboratory assays indicate bollworm larvae can detect Bt proteins, which may cause behavioral differences. Plant stress from factors including fertility and water availability causes changes in plant physiology and Bt expression. Our objective was to determine whether nitrogen and irrigation influenced bollworm behavior in Bt cotton by recording the vertical distribution of eggs and larvae over time. We conducted small plot experiments with Cry1Ac + Cry1F cotton in 2016 and 2017 with three nitrogen rates, along with irrigated and nonirrigated treatments during 2017. Bollworm locations were determined by in-field examination of 10–20 cotton plants per plot over 6–8 wk. The location of each egg and larva was recorded by node, with instar estimation of each larva. Oviposition was higher in in plots receiving nitrogen; first and second instars were also more common in plots receiving nitrogen or irrigation, whereas older instars had similar numbers among treatments. Oviposition was more evenly distributed throughout the canopy earlier in the sampling period than during later weeks, with more eggs in the top third of the canopy in only three of 14-wk. Early instars were also evenly distributed throughout the canopy. Later, instars moved to the middle portions of the canopy, away from bottom nodes, and did not move toward the terminal. Understanding bollworm behavior can inform both crop scouting and resistance management decisions.
Sugarcane aphid, Melanaphis sacchari Zehtner (Hemiptera: Aphididae), outbreaks on grain sorghum were first detected in the United States in 2013. The spread of sugarcane aphid across the sorghum-producing regions of North America necessitated increased insecticide use to mitigate economic loss. A field experiment to develop economic thresholds for sugarcane aphid was conducted 15 times across seven locations across the southern United States during 3 yr (2014–2016). Grain sorghum hybrids were evaluated by measuring yield in response to a range of aphid infestations.Yield–aphid population density relationships were described by linear function, which facilitated calculating economic injury levels and economic thresholds. The slopes of the yield–aphid density regressions were significant, negative, and relatively stable across locations, years, and agronomic conditions. The relationships aggregated into two groups, populations that exhibited relatively slow and fast population growth, and common economic injury levels were determined using control costs and market values of grain. Average economic injury levels of 37 and 102 aphids per leaf were most applicable to the two groupings of sorghum/aphid relationships and aphid population growth. Using field-based sugarcane aphid population doubling time estimated from weekly observations of aphid densities, economic thresholds were calculated, ranging from 19 to 132 aphids per leaf across the 15 locations-years. Without site-specific knowledge of a slow-growing aphid population and given cost and market price variability of the system, a 40 aphid per leaf threshold is most prudent to use across the range of hybrid, environmental, and market conditions experienced in this study.
Spodoptera frugiperda (J.E. Smith) is an invasive pest species that threatens maize production by small holder farmers in Africa. Bt maize that express Cry proteins have been used effectively for control of this pest in the United States, Canada, and several countries in South America. Spodoptera frugiperda has evolved resistance to Cry1F Bt maize in Puerto Rico, Brazil and United States, and Cry1Ab Bt maize in Brazil. This study provides the first data on the efficacy of Bt maize for the control of S. frugiperda in Africa. Susceptibility levels of nine S. frugiperda populations were evaluated between January 2018 and May 2018, including a laboratory reared reference population. Larval feeding bioassays were conducted in which plant tissue of maize expressing Cry1Ab (single-toxin event - designated Bt1) or Cry1A.105 + Cry2Ab2 (pyramid-toxin event - designated Bt2), were fed to larvae. Survival and different life history parameters were recorded. Results indicate moderate survival on Bt1 maize, which supports field observations of commercial level control provided by this event. Very high levels of S. frugiperda larval mortality occurred on Bt2 maize (<1% survival). The moderate susceptibility of S. frugiperda to Cry1Ab could be ascribed to the latter being a low-dose event for this pest, as well as the fact that the individuals which initially arrived on the continent may have carried alleles with resistance to this protein. Moderate overall survivorship (4–35%) of S. frugiperda on Cry1Ab maize in South Africa reflects the possible presence of alleles resistant to this toxin, indicating the importance of future resistance monitoring.
The polyphagous shot hole borer (Euwallacea nr. fornicatus, Coleoptera: Curculionidae: Scolytinae), an exotic and invasive ambrosia beetle, was recently found attacking a number of tree species in Los Angeles, Orange, Riverside, and San Diego Counties in southern California. Their colonization and subsequent inoculation of a suite of symbiotic fungi that cause Fusarium Dieback, has resulted in extensive mortality of some tree species, including, California sycamore (Platanus racemose Nutt.). There are no sustainable control options for polyphagous shot hole borer other than maintaining tree vigor and removal of severely infested host material. The effectiveness of therapeutic treatments of an injected systemic insecticide containing emamectin benzoate (EB) alone and in combination with a systemic fungicide, propiconazole (P), was evaluated over a 4-yr period for maintaining the health of individual sycamore trees infested by polyphagous shot hole borer. All treatments containing EB reduced levels of polyphagous shot hole borer colonization and associated sap flow at attack sites compared to untreated controls. A second trial evaluated preventative treatments of EB and P alone or combined to protect individual sycamore from colonization by polyphagous shot hole borer. After 45 mo posttreatment, all treatments significantly reduced polyphagous shot hole borer attack levels and successful attacks compared to untreated controls (EB + P > EB alone > P alone). We concluded that EB alone or combined with P are acceptable therapeutic and preventative treatments for management of polyphagous shot hole borer in California sycamore in southern California.
The redbay ambrosia beetle, Xyleborus glabratus Eichhoff, is native to Southeast Asia, where it specializes on Lauraceae trees. It forms a symbiosis with the ambrosia fungus Raffaelea lauricola T.C. Harr., Fraedrich & Aghayeva, which can act as a pathogen in living host trees. The beetle and fungus were recently introduced into the United States, where they have killed millions of native Lauraceae trees and threaten the avocado industry. These introduced populations have limited genetic variation. In the native range, the fungi are genetically variable, but the native genetic variability of the beetles is unknown. It is important to assess the beetle's native genetic variation because different lineages may vary in the capacity to vector this fungus, which may affect disease etiology. Here, we analyzed genetic variation in several Chinese, Taiwanese, and Vietnamese populations of X. glabratus using mitochondrial (COI) and nuclear DNA (CAD) markers. Phylogenetic analysis revealed nine COI haplotypes and four CAD genotypes. Uncorrected ‘p’ distance for intrapopulation comparisons ranged from 0 to 0.1 and 0 to 0.013 and interpopulation comparisons ranged from 0.137 to 0.168 and 0.015 to 0.032 for COI and CAD, respectively. Two populations exceeded the range of intraspecific nucleotide differences for both genes. Given that individuals from these populations also exhibited consistent morphological differences, they are described as two new species: Xyleborus insidiosus Cognato & Smith, n. sp. and Xyleborus mysticulus Cognato & Smith, n. sp. Xyleborus glabratus was redescribed and a lectotype was designated to facilitate its recognition in light of these new species. These results indicate that X. glabratus is genetically variable and is related to two morphologically similar species. Whether these new species and X. glabratus lineages associate with different fungal strains is unknown. Given that the biology and host colonization of these new species are unknown, preventing their introduction to other regions is prudent.
Enhanced detoxification and target mutations that weaken insecticide binding ability are major mechanisms of insecticide resistance. Among these, over-expression or site mutations of carboxylesterase (CarE), cytochrome P450s (CYP450), and glutathione-S-transferase (GST) were the main form responsible for insecticide detoxification; however, transcript-level analysis of the relationship of detoxification gene mutations with chlorpyrifos (an organophosphorus insecticide) resistance is scarce thus far. In this study, multiple sites exhibiting polymorphisms within three detoxification genes were firstly examined via sequencing among different chlorpyrifos-resistant and susceptible individuals of Laodelphax striatellus. For example, the mutation frequencies of A374V in LsCarE16 were 83, 33, and 3%, S277A in LsCarE24 were 88, 28, and 3%, E36K in LsCYP426A1 were 100, 65, and 0% for chlorpyrifos-resistant, resistant decay, and susceptible individuals, respectively. Analysis also found expression levels of GSTd1, GSTt1, GSTs2, CYP4DE1U1, and CYP425B1 are coordinated with chlorpyrifos resistance levels; moreover, we found the deficiencies of 43S and 44A as well as two point mutations of E60D and Q61H at N-terminal region of the OP potential target acetylcholinesterase (AChE) in high resistant but not in low-chlorpyrifos resistant individuals. The results above all demonstrated the dynamic evolutionary process of insecticide resistance and revealed some resistance factors that only played roles at certain resistance level; high insecticide resistance in this example is the result of synergistic impact from multiple resistance factors.
The effects of kaolin and bunch-zone leaf removal on populations of predatory mites Kampimodromus aberrans (Oudemans) and Typhlodromus pyri Scheuten were assessed in the context of four trials (2015–2016) carried out against Lobesia botrana (Denis and Schiffermüller) (Lepidoptera: Tortricidae) in vineyards located in north-eastern Italy. Laboratory experiments were performed to evaluate the effects of kaolin on the survival and fecundity of K. aberrans and T. pyri populations originating from the same grape-growing area. In field trials, kaolin caused a gradual decrease in population density levels of both phytoseiid species (with the maximum reduction ranging from 49 to 91%) with a complete population recovery in the next spring. In laboratory experiments, kaolin was moderately harmful to both species, reducing their fecundity significantly (around 60%). Bunch-zone leaf removal determined lower phytoseiid populations in all trials, but this effect was significant only for K. aberrans in one of them. A limited use of kaolin and the adoption of bunch-zone leaf removal did not irreversibly affect phytoseiid populations in vineyards and thus can be considered compatible with IPM strategies.
Similar to other pear psylla species in Europe and America, Cacopsylla chinensis (Yang and Li) is one of the most important pests that causes yield loss in commercial pear orchards in China.To investigate effective essential oils as alternatives to conventional pesticides against C. chinensis, 26 essential oils derived from commonly used Chinese spices and medicinal herbs were screened for insecticidal activity. Among these, the essential oil from Perilla frutescens (L.) Britton leaves was the top performer; it exhibited strong and acute toxicity against pear psylla, with an LD50 value of 0.63 μg per adult. Then, we tested the constituents of the essential oil and its toxicity in the field. Field trials showed a 72% corrected reduction in the first–second-instar population 7 d after spraying P. frutescens leaf oil solution at a concentration of 1 mg/ml and a 47% corrected reduction at days 3 and 14.This report is the first to document the application of essential oil from P. frutescens leaves to control C. chinensis under field conditions. Our results suggest that P. frutescens oil can be considered a novel potential pesticide for C. chinensis control in pear orchards.
Melon fly, Zeugodacus cucurbitae (Coquillett), is a serious pest of tropical horticulture, causing damage to cucurbits, other fruiting vegetables, and certain tree fruits. The deployment of male lures comprises an important component of several detection and control strategies for this pest, with the main male attractant currently in use being cuelure (CL). A novel fluorinated analog of CL, raspberry ketone trifluoroacetate (RKTA), has been developed for the control of Bactrocera tryoni, a related pest; here, we test this compound for attraction to Z. cucurbitae. In outdoor screen cage testing, observations showed both more flies on filter papers, and a higher percentage of flies feeding, on papers treated with RKTA than on those with CL or melolure (ML). Field trapping with both yellow sticky traps and bucket traps found that RKTA captured more flies during the first 6 h of trapping than CL, while trap captures in the subsequent 18 h did not differ between the two lures. When comparing combined 24 h trap captures, yellow sticky traps containing RKTA captured more flies than those with CL, while bucket trap captures did not vary by lure. Analysis of lures weathered on filter paper found that nearly all applied RKTA hydrolyzed to RK within 6 h. Fine-scale melon fly behaviors digitally recorded in the field showed median resting distances from the lure of responding flies were shorter for RKTA than for CL. This study demonstrates the inherent attractiveness of RKTA while also highlighting the instability of this compound due to hydrolysis.
Acetamiprid and imidacloprid are two important neonicotinoid insecticides that are widely utilized under field conditions for the management of sucking insect pests, including the solenopsis mealybug Phenacoccus solenopsis Tinsley (Hemiptera: Pseudococcidae). Although some information is available regarding their lethal effects, nothing is currently known about the sublethal effects of these insecticides. We, therefore, performed a series of experiments to test the lethal and sublethal effects of these chemicals on oviposition duration and fecundity. We also assessed sublethal effects on feeding behavior using the electrical penetration graph (EPG) technique. The results of this study reveal that acetamiprid toxicity is higher than imidacloprid and that both insecticides have negative effects on the oviposition, fecundity, and feeding behavior of P. solenopsis when applied at sublethal dosages. These chemicals also significantly reduce oviposition duration and fecundity and significantly prolong nonprobing duration, increase penetration problems, and reduce phloem and xylem feeding activities when compared with adults exposed to just water. No significant differences were detected in all waveform durations and events when adults previously exposed to foliage treated with each of these two insecticides were compared. The results of this study, therefore, suggest that both insecticides are capable of protecting crops from mealybug damage by not only killing these pests directly but also reducing their fecundity and inhibiting feeding behaviors when applied at sublethal dosages.
Field-scale data on the relationship between pollinator activity and fruit set are scarce for rabbiteye blueberries (Vaccinium virgatum Aiton). We measured the densities of Apis mellifera L. (Hymenoptera: Apidae), Habropoda laboriosa F. (Hymenoptera: Apidae), Bombus Latreille (Hymenoptera: Apidae) spp., and Xylocopa virginica L. (Hymenoptera: Apidae) in 7–21 commercial fields during each of 3 yr in Louisiana and Mississippi. Foraging bees were counted on 10 ‘Tifblue’ bushes per field on 2 d during bloom, and the density of bees per flower was calculated based on the number of flowers open during the counts. Fruit set was measured 30 d after bloom. The impact of foraging activity on fruit set was inconsistent when densities of either all foragers or foragers of individual taxa were considered. Strong associations were observed only in 2001, with fruit set increased by H. laboriosa and Bombus and with a weaker contribution by A. mellifera. Floral robbery by X. virginica had no measurable negative effects. Populations of H. laboriosa were more consistent than those of other bees across sites. Managed colonies of A. mellifera were added at two densities (12.5 or 2.5 colonies per hectare) in seven fields each in 2001. These supplemental bees did not result in greater forager densities or fruit set in stocked fields. The observations show the challenge of field-scale pollination tests but provide an initial framework for rabbiteye blueberry growers to assess the availability of foraging bees early in bloom to help decide whether to add supplemental A. mellifera to try to enhance pollination if populations of non-Apis bees are low.
The development of acoustic systems for detection of wood-boring larvae requires knowledge of the features of signals produced both by insects and background noise. This paper presents analysis of acoustic/vibrational signals recorded in tests using tree bolts infested with Anoplophora glabripennis (Motschulsky) (Coleoptera: Cerambycidae) (Asian longhorn beetle) and Agrilus planipennis Fairmaire (Coleoptera: Buprestidae) (emerald ash borer) larvae. Based on features found, an algorithm for automated insect signal detection was developed. The algorithm automatically detects pulses with parameters typical for the larva-induced signals and rejects noninsect signals caused by ambient noise. The decision that a wood sample is infested is made when the mean rate of detected insect pulses per minute exceeds a predefined threshold.The proposed automatic detection algorithm demonstrated the following performance: 12 out of 15 intact samples were correctly classified as intact, 23 out of 25 infested samples were correctly classified as infested, and five samples out of the total 40 were classified as ‘unknown.’ This means that a successful wood-sample classification of 87.5% was achieved, with the remaining 12.5% classified as ‘unknown,’ requiring a repeat of the test in a less noisy environment, or manual inspection.
Barrier applications, treating vegetation and other potential mosquito resting areas with residual pesticides, have become standard practice for commercial pest management professionals offering mosquito control services. These treatments are generally effective in reducing numbers of the Asian tiger mosquito, Aedes albopictus (Skuse). In the temperate climates, adult Ae. albopictus populations are naturally eliminated each winter and must be grown from diapausing eggs the following spring. Therefore, early-season control interventions timed before populations rebound may further reduce population growth compared with interventions that take place after the population has peaked. We compared Early (1 June) barrier applications of lambda-cyhalothrin (Demand CS) mixed with the insect growth regulator pyriproxyfen (Archer IGR) to Late applications (31 July) in urban and suburban residential parcels in New Jersey. These applications resulted in 43 and 51% reductions in adult Ae. albopictus populations in the Early and Late intervention study parcels, respectively, when compared with the untreated Controls. Indirect applications of pyriproxyfen (i.e., rainwater runoff transferring pesticide) to potential larval habitat did not cause mortality in laboratory larval bioassays but direct mist applications of the Archer and Demand combination to larval habitats led to elevated larval mortality over a 6-wk period. The Early-season intervention offered no advantage in efficacy on adult populations compared with the Late-season intervention, which targeted peak mosquito populations. Our study provides support for the efficacy of barrier applications and illustrates the importance of timing barrier treatments to coincide with established Ae. albopictus action thresholds.
Intentional and unintentional openings in a building's envelope provide opportunities for unwanted pests to enter buildings. The brown marmorated stink bug, Halyomorpha halys (Stål), is one such pest, causing a significant domestic winter nuisance in many locations. One important means of pest control is exclusion, or blocking openings through which they can enter, although some openings are intentional and cannot be completely blocked without putting a building at risk. To help understand what size openings are relevant to entry, adult H. halys ready for overwintering were driven out of heated boxes through openings designed to limit passage by their lateral pronotal and dorsoventral dimensions. Pronotally limited holes of 8 mm wide were passed by only one female (3.3% of those tested), and no females and only one male (3.3%) passed through 7-mm-wide holes. For dorsoventrally limited slits, few (13%) of females passed through 4-mm-high slits, and no individuals passed through 3-mm-high slits. Dorsoventral heights and pronotal widths of 930 individuals collected in Virginia were measured. Females were consistently larger, with pronota averaging 8.33 mm wide to the males' 7.47 mm and heights at the point of leg movement restriction averaging 4.03 mm to the males' 3.50 mm. Based on experimental data and size data, we conclude that most H. halys individuals will be excluded by slits smaller than 3 mm and holes smaller than 7 mm.
Chlorantraniliprole, an anthranilic diamide insecticide, is widely used for controlling lepidopteran pests, because of its high insecticidal activity. However, overuse of chlorantraniliprole has led to the selection of resistance in many insect pests, including Chilo suppressalis (Lepidoptera:Crambidae), one of the most damaging rice pests in China. In this study, resistance levels to chlorantraniliprole for C. suppressalis was surveyed from eight populations of three provinces in China. The levels of resistance were ranged from 34.4-fold to 284.0-fold compared with a susceptible population.Then, a 15402 bp fragment of the full-length cDNA of ryanodine receptor gene (CsRyR) from the XS strain, the highest resistant population, and a 1992 bp fragment of CsRyR cDNA encoding the carboxyl-terminal of CsRyR gene from the other seven populations were sequenced. A common previously identified mutation that was associated with chlorantraniliprole resistance against C. suppressalis, G4910E, was not detected in any of the eight populations in this study. However, another mutation I4758M was found in all seven resistant populations. Furthermore, the relative mRNA expression levels of CsRyR gene in the seven resistant populations were all reduced compared with susceptible strain. Our study provides new insights into the basis of monitoring the development of resistance and the mechanism of resistance to chlorantraniliprole in C. suppressalis.
The southern corn rootworm, Diabrotica undecimpunctata howardi Barber (Coleoptera: Chrysomelidae), was exposed over multiple generations to vacuolar (v)ATPase-A double-stranded (ds)RNA, first as adults and later, as neonate larvae. During adult selection, high mortality and lower fecundity were observed in the RNAi-selected cages after beetles were exposed to sublethal dsRNA concentrations that varied between LC40 and LC75. During larval selection, a delay in adult emergence and effects on population growth parameters were observed after neonates were exposed to sublethal dsRNA concentrations that varied between LC50 and LC70. Some of the parameters measured for adult emergence such as time to reach maximum linear adult emergence, time elapsed before attaining linear emergence, termination point of the linear emergence, and total days of linear emergence increase, were significantly different between RNAi-selected and control colonies for at least one generation. Significant differences were also observed in population growth parameters such as growth rate, net reproductive rate, doubling time, and generation time. After seven generations of selection, there was no indication that resistance evolved. The sublethal effects caused by exposures of southern corn rootworm to dsRNAs can affect important life history traits and fitness especially through delays in adult emergence and reduction in population growth. Although changes in susceptibility did not occur, the observation of sublethal effects suggests important responses to potential selection pressure. Assuming resistance involves a recessive trait, random mating between susceptible and resistant individuals is an important factor that allows sustainable use of transgenic plants, and delays in adult emergence observed in our studies could potentially compromise this assumption.
Insect cytochrome P450 monooxygenases play an important role in plant allelochemical detoxification. In this study, a full-length gene CYP305A1 of the P450 Clan 2 family was cloned from Aphis gossypii Glover, and its promoter was identified and characterized. The transcript level of CYP305A1 and its promoter activity were significantly induced by two plant allelochemicals, gossypol and 2-tridecanone. Furthermore, the 5′-end promoter region from -810 to +62 bp was demonstrated to be essential for basal transcriptional activity of CYP305A1, and the promoter region from -810 to -581 bp was shown as an essential plant allelochemical responsive element and had a cis-element 5′-CACACTA-3′ as the binding site of aryl hydrocarbon receptor. Interestingly, there was an identical overlapping region of 1,094 bp between CYP305A1 promoter and the venom protease gene. When the expression of CYP305A1 gene was knocked down by RNA interference with CYP305A1 dsRNA, the expression of the venom protease gene was decreased. However, the knockdown of the expression of the venom protease gene did not affect the CYP305A1 expression. These results provide important insights for understanding the functions of P450 genes and the regulatory mechanism of P450 gene expressions in the resistance of Aphis gossypii Glover to plant allelochemicals.
The diamondback moth, Plutella xylostella (Linnaeus) (Lepidoptera: Plutellidae), is one of the most important pests of cruciferous crops in Iran and is controlled mostly by fenvalerate. The susceptibility to fenvalerate was investigated for four populations of P. xylostella. Bioassay results indicated significant differences among the populations tested. The highest level of resistance to fenvalerate was obtained for the Khuzestan (Khz) population (resistance ratio = 9.5). Survival was suppressed by diethyl maleate, piperonylbutoxide, and triphenyl phosphate, which confirmed that resistance to fenvalerate is caused by glutathione S-transferases (GSTs), mixed function oxidases, and esterases, respectively. Up to 8.6-, 2-, 2.7-, and 1.75-fold increases in GSTs, esterase (α-naphthylacerate and β-naphthyl acetate as substrate), and cytochrome P450 monooxygenases activities in resistant strains when compared with the susceptible one, were observed, respectively. The expression of six GST genes of P. xylostella including GSTs1, GSTe2, GSTe4, GSTo4, GSTd4, and GSTd5 were analyzed. The quantitative PCR analysis showed that three of the PxGSTs had the highest expression levels in the Khz population. Two of the GSTs (GSTd4 and PxGSTe2) exhibited highest expression level in both Khz and Alborz (Alb) populations. Therefore, PxGST genes were involved in fenvalerate resistance in P. xylostella. Overall, the mechanisms of insecticide resistance in diamondback moth populations in four regions of Iran were related to GST, esterase, and cytochrome P450 monooxygenase activities.
Regis F. Stacke, Tiago Giacomelli, Eduarda S. Bronzatto, Stefany A. Halberstadt, Cinthia G. Garlet, Dionei S. Muraro, Jerson V. C. Guedes, Oderlei Bernardi
Soybean looper (SBL), Chrysodeixis includens (Walker) (Lepidoptera: Noctuidae), is an important pest of soybean and cotton in Brazil. The use of insecticides is one of the main control tactics against this pest. To support Integrated Pest Management (IPM) and Insect Resistance Management (IRM) programs, we characterized the susceptibility of Brazilian populations of SBL to insecticides. Field populations were collected from soybean fields during the 2016–2017 and 2017–2018 crop seasons. In the laboratory, late L2/early L3 larvae were exposed to insecticides in diet-overlay or topical bioassays. Field populations of SBL showed high susceptibility to spinetoram (LC50 = 0.074–0.25 μg a.i. per cm2), indoxacarb (LC50 = 0.46–0.94 μg a.i. per cm2), thiodicarb (LC50 = 9.14–36.61 μg a.i. per cm2), chlorantraniliprole (LC50 = 0.15–0.57 μg a.i. per cm2), flubendiamide (LC50 = 0.45–2.01 μg a.i. per cm2), and chlorfenapyr (LC50 = 0.15–0.25 μg a.i. per cm2); the resistance ratios were less than 16-fold. In contrast, SBL populations have reduced susceptibility to lambda-cyhalothrin (LC50 = 3.71–9.54 μg a.i./cm2), methoxyfenozide (LC50 = 0.67–4.23 μg a.i. per cm2), novaluron (LC50 = 27.52–77.63 μg a.i. per cm2), and teflubenzuron (LC50 = 13.41–73.02 μg a.i. per cm2). The resistance ratios relative to a Lab population (susceptible of reference) was up to 38-, 63-, 1,553-, and 5,215-fold, respectively. These high resistance ratios can be associated with resistance evolution. Implications of these findings to IPM and IRM programs are discussed.
The mosquito Anopheles pseudopunctipennis (Theobald) is the principal vector for malaria in Latin-America. Aedes aegypti (L.) (Diptera: Culicidae) is the key vector of four important arboviral diseases: dengue, yellow fever, Zika, and chikungunya. Controlling larval stages to reduce the production of new adult mosquitoes is part of the integrated vector management strategies. However, there are few studies about the olfactory behavior on immature stages of mosquitoes, especially in An. pseudopunctipennis. In this work, we have evaluated the behavior of An. pseudopunctipennis and Ae. aegypti larvae in response to attractant or repellent stimuli through a video-tracking analysis. We used the software EthoVision to obtain behavioral variables related to the swimming activity, such as distance, speed, and mobility status. The response to the repellents stimulus results in an increase of the swimming activity and the absolute angular velocity in both species. Otherwise, the responses to the possible attractants stimulus results in a decrease of the activity of the larvae only for Ae. aegypti. The effects of these compounds were weaker in Anopheles; probably as a consequence of their adaptations to different aquatic ecosystems. The study of the larval olfactory response could contribute to the development of new control tools based on ‘push–pull’ strategies by ‘pushing’ mosquitoes away from certain places using repellents, and ‘pulling’ them towards other places like traps baited with attractive cues.
A proteomic method combining two-dimensional polyacrylamide gel electrophoresis and tandem mass spectrometry was used to compare the hemolymph expression profiles of a beta-cypermethrin-resistant Blattella germanica L. strain (R) and a susceptible strain (S) after 24 h of beta-cypermethrin induction.The results showed that there were 42 differentially expressed proteins after induction of the R strain: 4 proteins were upregulated and 38 proteins were downregulated. One hundred one hemolymph proteins were differentially expressed after induction of the S strain: 53 proteins were upregulated and 48 proteins were downregulated. The identified proteins were mainly classified into the following categories: energy metabolism proteins such as arginine kinase and triose phosphate isomerase, detoxification-related proteins such as glutathione S-transferases (GSTs), signal molecule-regulated proteins such as nitric oxide synthase (NOS), and other proteins such as kinetic-related proteins and gene expression–related proteins. Several proteins show significant differences in response to short-term stress and long-term adaptation, and differential expression of these proteins reflects an overall change in cellular structure and metabolism associated with resistance to pyrethroid insecticides. In summary, our research has improved the understanding of the molecular mechanisms of beta-cypermethrin resistance in German cockroaches, which will facilitate the development of rational methods to improve the management of this pest.
Cytochrome (CYP) P450s are a superfamily of enzymes that detoxify xenobiotics and regulate numerous physiological processes in insects. The genomes of phytophagous insects usually contain large numbers of P450s, especially within the CYP3 clan. Within this clan, CYP6 subfamily members help detoxify plant host secondary metabolites. In this study, we analyzed three CYP6 genes in the highly polyphagous invasive pest, Halyomorpha halys (Stål), commonly known as brown marmorated stink bug. We characterized and validated the expression of HhCYP6BQ27, HhCYP6BK13, and HhCYP6BK24 among sexes, tissues (gut, fat body, and Malpighian tubules) and hosts (apple, corn, soybean). Sequence characterization by amino acid alignments confirmed the presence of conserved motifs typical of the P450 superfamily. No significant differences existed in gene expression among sexes or when fed different hosts, suggesting that these transcripts might have broad substrate specificities. However, significant differences in gene expression were observed among the tissues studied and were gene-dependent. Collectively, the results show that H. halys differentially expressed CYP6 genes among tissues, which may be related to important and specific physiological functions. This study has increased our understanding of H. halys biology that can be useful for functional studies and can potentially be exploited in developing sustainable pest management strategies.
Juvenile hormone (JH) regulates many physiological processes in insect development, diapause, and reproduction. Juvenile hormone binding protein (JHBP), the carrier partner protein of JH, is essential for the balance of JH titer to regulate the metamorphosis and development of insect. In this study, two JHBP genes were identified from Helicoverpa armigera (Hübner) (Lepidoptera: Noctuidae), namely HaJHBP1 and HaJHBP2. The tissue and temporal expression pattern revealed that both HaJHBP1 and HaJHBP2 were dominantly expressed in larval fat body, and their high transcription stages were detected in fourth and fifth instars. The ingestion of methoprene, a JH analogue, significantly induced the expression of HaJHBP1 and HaJHBP2. However, both HaJHBP1 and HaJHBP2 mRNA levels were significantly downregulated after treated with a JH antagonist, precocene. When subject to starvation, larvae showed a marked suppressive effect in the expression of HaJHBP1 and HaJHBP2. These results indicate that JHBP plays a part in the JH-regulated metabolism, growth, or development in reaction to different nutritional conditions.
Diaphorina citri Kuwayama (Hemiptera: Liviidae) is one of the most common pests impacting citrus orchards in southern China. Samples of D. citri were collected in southern China in order to systematically explore the genetic architecture of the species. Mitochondrial cytochrome b (Cytb) and cytochrome coxidase subunit I (COI) were amplified by polymerase chain reaction (PCR) which allowed highlighting low haplotype and nucleotide diversities among the population. Two clades could be observed in the haplotype network. Moreover, Bayesian and maximum parsimony phylogenetic trees were constructed based on the sequences of Cytb and COI. Here, we report on the significant genetic variation of the species when comparing southwestern China with other regions of southern China (southern and southeastern). This analysis also suggested that the genetic structure of D. citri in China originates may from long-term climate fluctuations concomitant with recent disturbances resulting from human activity. Combined with previous data, the present work indicates that D. citri potentially entered China through two distinct invasion routes and spread within the country via three transmission paths.
Cultivation of aphid-resistant soybean varieties can reduce yield losses caused by soybean aphids. However, discovery of aphid biotypes that are virulent on resistant soybean greatly threatens sustained utilization of host plant resistance to control soybean aphids. The objective of this study was to identify and genetically characterize aphid resistant soybean accessions in a diverse collection of 308 plant introductions in maturity groups (MG) I and II. In large-scale screening experiments conducted in the greenhouse, we identified 12 soybean accessions (10 aphid-resistant and 2 moderately resistant), including nine previously not reported for resistance against soybean aphids. Three accessions (PI 578374, PI 612759C, and PI 603546A) and the Rag3 resistant check (PI 567543C) were susceptible when infested with a high initial aphid level but resistant when infested with a low initial aphid level, a phenomenon termed as density-dependent aphid resistance. Six accessions (PI 054854, PI 378663, PI 578374, PI 612759C, PI 540739, and PI 603546A) conferred antibiosis, five (PI 438031, PI 603337A, PI 612711B, PI 437950, and PI 096162) conferred both antibiosis and antixenosis, while one (PI 417513B) had neither when tested in no-choice and pairwise choice experiments. Molecular genotyping of the 12 accessions using single-nucleotide polymorphism (SNP) markers linked to known aphid resistance (Rag) genes revealed that PI 578374 and PI 540739 did not have any tested marker variants and could potentially carry unreported Rag genes. Genome-wide association analyses for MG I accessions identified genomic regions associated with aphid resistance on chromosomes 10 and 12 for each level of initial aphid colonization.
Plant long-term response against chewing insects could become stronger than initial reactions and even turn into systemic. The objectives of the present study were 1) to evaluate whether the long-running attack to the stem by corn borers can improve the stem antibiotic properties; 2) to check whether hydroxycinnamic acids could be involved in this antibiotic response; 3) and to check whether elicitation by Sesamia nonagrioides Lef. (Lepidoptera: Noctuidae) regurgitant could activate long-term plant responses. In this sense, we observed that long-term feeding by S. nonagrioides larvae induced genotype-dependent changes in stem antibiosis and phenolic profiles, but the hydroxycinnamate content does not have a significant role in the systemic defense induced by the attack. In addition, response to long-term feeding by larvae could not be fully mimicked by elicitation using S. nonagrioides regurgitant alone. For the first time, it has been demonstrated that ‘long-term’ attack to the stem by corn borers can increase the stem antibiotic properties, and this has to be considered attending to breeding strategies.
Eliete Meire de Paula Silva, Tamíris Alves de Araújo, Rodrigo Soares Ramos, Lucas de Paulo Arcanjo, Daiane das Graças do Carmo, Adriano Cavalleri, Marcelo Coutinho Picanço
Bell pepper [Capsicum annuum L. (Solanales: Solanaceae)] is cultivated worldwide, and the consumption of its fruits has increased because this plant is a functional food rich in antioxidants. Frankliniella schultzei (Trybom) is an important bell pepper pest worldwide. Sampling plans are essential components of integrated pest management programs. Thus, we developed a conventional sampling plan for F. schultzei in bell pepper. The work was conducted during 2 yr in commercial bell pepper fields in the vegetative, flowering, and fruiting stages. Our results indicated that the sample and the ideal technique for the evaluation of F. schultzei populations in bell pepper were the apical canopy and the beating of this part of the plant in a white plastic tray, respectively. The densities of F. schultzei were adjusted to a negative binomial distribution, and they presented a common aggregation parameter (Kcommon = 0.3176), which made it possible to generate a sampling plan that could be used in bell pepper plantations at all plant growth stages. The developed sampling plan consisted of an evaluation of 61 plants per field that took 23 and 38 min to run on 1 and 5 ha fields, respectively. In the 1 and 5 ha fields, US$1.27 and US$1.92 were spent per sampling, respectively. Thus, the plan developed in this work can be incorporated into integrated management programs for F. schultzei in bell pepper crops by facilitating the accurate, representative and feasible sampling of this pest at all stages of the plant.
The red flour beetle, Tribolium castaneum (Herbst) (Coleoptera: Tenebrionidae), is a common pest in rice mills. With limited information in the literature addressing T. castaneum in rice processing facilities, we examined the spatial and temporal distribution of T. castaneum inside and outside of three commercial rice milling facilities and one rice packaging plant from June 2012 to August 2014 using pheromone-baited dome traps. Each mill had very different population trends with fewer numbers collected in rough rice storage areas. T. castaneum were more commonly collected in processing areas. Beetle infestation at all the mills was evaluated using the threshold of mean beetle capture of 2.5 beetles per trap per 2 wk period. Trap captures were below threshold for all but one facility. Temperatures inside were ~1°C warmer than outside temperatures, with these temperature differences more noticeable during cool months (October–March). Higher numbers of T. castaneum were captured in 2012 in comparison to 2013, with higher beetle numbers observed during warmer (April–September) than cooler months. With variation in trap capture of T. castaneum occurring among all facilities, this study illustrates that having a monitoring program designed for each facility is important to help managers decide when and where to apply pest management tactics. The use of pheromone traps could provide information to mill managers to find locations within a mill that are most vulnerable to infestation by T. castaneum, and to assist with the timing of control interventions.
Hermetic grain storage technology offers a viable chemical-free approach to control storage insects. However, there is limited knowledge on how hypoxia affects the survival of insect life stages during grain storage in hermetic bags. We exposed Tribolium castaneum (Herbst) (Coleoptera: Tenebrionidae) eggs (2 d), young larvae (7 d), old larvae (21 d), pupae (28 d), and adults (2 d after emergence) to 2, 4, 8, and 20.9% oxygen levels for 1, 3, 5, 10, and 15 d and assessed subsequent mortality. At 2% oxygen, complete mortality was achieved in 3 d for eggs and young larvae, 10 d for old larvae and pupae, and 15 d for adults. At 4% oxygen, 15 d were required to kill all eggs and old larvae but not the other insect life stages. At 8% oxygen after 15 d, complete mortality of any insect life stage was not observed; but even a relatively short exposure (1–3 d) caused significant developmental delays in immature insects. Our study shows potential utility of hermetic technology for control of T. castaneum, but internal oxygen should be maintained below 2% level for at least 15 d for complete control. Increased oxygen levels improved the development of all insect life stages leading to increased adult emergence. There is a need to explore exposure time required to achieve complete mortality of all insect life stage above the 2% oxygen level.
Filter cake and Triplex are powdered by-products of aluminum sulfate and soap factories in Ethiopia, respectively. This study was aimed at determining contact toxicity of filter cake and Triplex powders against maize weevil, Sitophilus zeamais Motschulsky. Lethal concentrations for 99% mortality (LC99) against S. zeamais were determined by exposing adults for 12 h to filter cake (0.5–8 g/m2) and Triplex (1–9 g/m2) in concrete arenas. Lethal times for 99% mortality (LT99) were determined by exposing adults over time (1–24 h) in concrete arenas to 3 g/m2 of filter cake and 9 g/m2 of Triplex. Exposed adults were transferred to containers with 30 g of organic wheat and held at 28°C and 65% RH for 14 d to determine mortality. LC99 values for S. zeamais adults were 7.54 and 23.46 g/m2 when exposed to filter cake and Triplex, respectively. The corresponding LT99 values were 21.92 and 39.62 h when exposed to filter cake and Triplex, respectively. Effective concentrations and times for the 99% reduction of progeny production were determined from percentage reduction in adult progeny relative to production in control treatments after 42 d. EC99 values for progeny reduction were 2.48 and 18.59 g/m2 for filter cake and Triplex treatments, respectively. The corresponding ET99 values for progeny reduction were 17.49 and 22.31 h for filter cake and Triplex, respectively. Sitophilus zeamais exposed to filter cake produced lower percentage insect-damaged kernels and weight loss thanTriplex. Filter cake was more efficacious against S. zeamais than Triplex.
Horn flies (Haematobia irritans (L.)) have long posed animal health and welfare concerns. Economic losses to the cattle and dairy industries from their blood-feeding behavior include decreased weight gain, loss in milk productivity, and transmission of bacteria causing mastitis in cattle. Horn fly management strategies are labor intensive and can become ineffective due to the horn fly's ability to develop insecticide resistance. Research indicates that for some cattle herds, genetically similar animals consistently have fewer flies suggesting those animals are horn fly resistant (HFR) and that the trait is heritable; however, it is currently unknown if cattle producers value this trait. Tennessee and Texas cow-calf producers were surveyed to estimate their willingness to pay for HFR bulls and to identify the factors affecting their decision to adopt a HFR bull in their herds. Results indicate that Tennessee and Texas cow-calf producers were willing to pay a premium of 51% and 59% above the base price, respectively, for a HFR bull with the intent to control horn flies within their herd. Producer perceptions of horn fly intensities and the HFR trait, along with their pest management practices, were factors that affected Tennessee and Texas producer willingness to adopt a HFR bull. In Texas, demographics of the producers and their farms also had a role. Knowing producers are willing to pay a premium for the HFR bull indicates that producers value the HFR trait and warrants additional research on the development, implementation, and assessment of the trait.
Nest temperature is a crucial variable that determines colony survival in social insects. The successful production and development of a new brood, therefore, depends on stable thermal conditions and limited temperature oscillations. Thermoregulatory processes are useful in controlling both individual activity and for the maintenance of colony temperature. We measured heat production generated by nurse bees working on brood combs of the stingless bee Melipona scutellaris (Hymenoptera, Apidae, Meliponini) in this study; our results enabled us to identify the existence of a new task performed by nurse bees, referred to here as ‘hot bees' because of their higher thorax surface temperature (4°C above that of other bees within the brood area). This additional heat has been little studied in stingless bees but is likely the result of thorax muscle contractions or, indeed, the development of this musculature as these are recently emerged individuals. We hypothesize that these ‘hot bees' contribute to the maintenance of warmth within the nest brood area.
Overwintering brown marmorated stink bugs (Halyomorpha halys) (Stål) are a notable domestic nuisance. In addition to disruptive activity, dead individuals remain in homes, sometimes in large numbers.To better understand the effects of these remains on overwintering behavior, adult H. halys were subjected to several experiments to test their responses to dead conspecifics. In non-tactile tests of individuals exposed to groups of dead conspecifics, H. halys did not respond to 1-yr-old desiccated dead conspecifics, but avoided corpses that were freshly killed. In tactile tests of individuals exposed to groups of dead conspecifics, H. halys joined those corpse aggregations significantly more often than not, and preferred corpses to cotton when given a choice. In tests of exposure of overwintering individuals to fresh dead conspecifics over the course of a winter, no necrophagy or evidence of survival advantage was observed, but overall females had higher survival rates than males.
Onion thrips (Thrips tabaci Lindeman) is a severe pest of onion (Allium cepa L.). Their management relies on frequent applications of foliar insecticides, including spinetoram (Radiant® SC), which has a novel mode of action and is effective at controlling large populations. However, despite being widely used for the past 10 yr, susceptibility to spinetoram has not been evaluated formally in New York state, where nearly 3,000 hectares of onion are planted annually. Over 2 yr (2017–2018), the susceptibility of onion thrips to spinetoram was assessed from populations collected in commercial onion fields in New York. LC50s for adults were generated from feeding assays and ranged from 2.07 to 5.08 ppm, but grower reports indicate that onion thrips populations continue to be susceptible to spinetoram. Moreover, both regional and temporal variations in susceptibility were similar among these populations based on survival at individual concentrations tested, despite significant differences in LC50s.These results suggest some genetic heterogeneity among onion thrips populations and serve as a valuable reference for the continued monitoring of onion thrips susceptibility to spinetoram, contributing to ongoing efforts to manage insecticide resistance in this system.
Sour rot is a complex disease of grapes caused by an interaction of yeast, acetic acid bacteria, and Drosophila spp. Application of insecticides (most commonly zeta-cypermethrin) targeting Drosophila has previously provided substantial control of sour rot in wine grapes of New York vineyards. In harvest season of 2018, a control failure of sour rot and high populations of Drosophila, mostly Drosophila melanogaster, were observed in a vineyard in the Finger Lakes region, NY, despite repeated applications of zeta-cypermethrin (Mustang Maxx).To determine if resistance was responsible for the control failure, we quantified the toxicity of zeta-cypermethrin and the four other insecticides registered for Drosophila control in NY vineyards. Diagnostic concentrations (susceptible strain LC95, 4 × LC95, and 16 × LC95) were used to evaluate percentage survival of the field flies relative to the susceptible Canton-S strain. Resistance to zeta-cypermethrin, acetamiprid, and malathion, but not to spinosad and spinetoram, was observed in the field-collected flies. This study provides evidence that insecticide resistance of Drosophila is associated with control failure of sour rot in some vineyards, and directly influencing grape production. The implications of these results to insecticide resistance monitoring and management are discussed.
Bactrocera curvipennis (Froggatt) is a polyphagous pest fruit fly endemic to New Caledonia that is weakly attracted to the male lure cue-lure (CL). Effective male lures are important for the monitoring and management of numerous pest species of Dacinae fruit flies. However, if a species is weakly responsive to these lures its detection and control is difficult. Recently in Oceania and Asia, more attractive male lures (isoeugenol, methyl-isoeugenol, dihydroeugenol, and zingerone) were identified for several weakly CL- and methyl eugenol (ME)responsive species. To determine if these lures may be more attractive to B. curvipennis, we field tested them in comparison to CL and ME in New Caledonia. Bactrocera curvipennis catch with isoeugenol-baited traps (mean 20.3 ± 3.0) was 15 times greater than with CL (1.3 ± 0.8) and catch with dihydroeugenol (5.7 ± 1.6) was four times greater than with CL. This is the first record of B. curvipennis responding to these lures. It was also the only species that responded to isoeugenol in this study. Bactrocera fulvifacies (Perkins) (Diptera: Tephritidae), a rarely encountered species ‘nonresponsive’ to male lures, was attracted to zingerone with its trap catch (2,574 flies) approaching that of Bactrocera tryoni (Froggatt) (Diptera: Tephritidae) at CL (2,724 flies). Another nonresponsive species, Dacus aneuvittatus (Drew) (Diptera: Tephritidae), was also trapped by zingerone-baited traps. This is the first record of these species responding to a male lure. The significantly greater response of B. curvipennis to isoeugenol would make it a considerably more effective attractant for use in surveillance and control programs.
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