BioOne.org will be down briefly for maintenance on 14 May 2025 between 18:00-22:00 Pacific Time US. We apologize for any inconvenience.
Registered users receive a variety of benefits including the ability to customize email alerts, create favorite journals list, and save searches.
Please note that a BioOne web account does not automatically grant access to full-text content. An institutional or society member subscription is required to view non-Open Access content.
Contact helpdesk@bioone.org with any questions.
The phase out of methyl bromide for the treatment of structures where grain is milled or processed has triggered a need to evaluate the effectiveness of alternative structural treatments such as sulfuryl fluoride and heat. Tribolium castaneum (Herbst) (red flour beetle) and Tribolium confusum Jacquelin du Val (confused flour beetle) (Coleoptera: Tenebrionidae) are primary targets for structural treatments, and impact of treatments on these species was evaluated in this study. Efficacy was measured by comparing beetle captures in pheromone- and kairomone-baited traps immediately before and immediately after treatments. Studies were conducted primarily in commercial wheat mills and rice mills, with the treatments conducted by commercial applicators. A meta-analysis approach was used to evaluate efficacy data collected from 111 treatments applied in 39 facilities. Findings confirm that structural fumigations and heat treatments greatly reduce pest populations within food facilities, but there was significant variation in the efficacy of individual treatments. Generally, the different treatment types (sulfuryl fluoride, methyl bromide, and heat) provided similar reductions in beetle capture using multiple metrics of beetle activity. The novel application of meta-analysis to structural treatment efficacy assessment generated a robust estimate of overall treatment efficacy, provided insights into factors potentially impacting efficacy, and identified data gaps that need further research.
Beekeepers who use honey bees (Apis mellifera L.) for crop pollination services, or have colonies making honey on or in close proximity to agricultural crops, are concerned about the reductions of colony foragers and ultimate weakening of their colonies. Pesticide exposure is a potential factor in the loss of foragers. During 2009–2010, we assessed changes in the field force populations of 9–10 colonies at one location per crop on each of the eight crops by counting departing foragers leaving colonies at regular intervals during the respective crop blooming periods. The number of frames of adult bees was counted before and after bloom period. For pesticide analysis, we collected dead and dying bees near the hives, returning foragers, crop flowers, trapped pollen, and corn-flowers associated with the cotton crop. The number of departing foragers changed over time in all crops except almonds; general patterns in foraging activity included declines (cotton), noticeable peaks and declines (alfalfa, blueberries, cotton, corn, and pumpkins), and increases (apples and cantaloupes). The number of adult bee frames increased or remained stable in all crops except alfalfa and cotton. A total of 53 different pesticide residues were identified in samples collected across eight crops. Hazard quotients (HQ) were calculated for the combined residues for all crop-associated samples and separately for samples of dead and dying bees. A decrease in the number of departing foragers in cotton was one of the most substantial crop-associated impacts and presented the highest pesticide risk estimated by a summed pesticide residue HQ.
The objective of this study was to manipulate ventilation rate to characterize interactions between stocks of honey bees (Apis mellifera L.) and ventilation setting on varroa mite (Varroa destructor Anderson and Trueman) mortality in honey bee colonies kept indoors over winter. The first experiment used colonies established from stock selected locally for wintering performance under exposure to varroa (n=6) and unselected bees (n=6) to assess mite and bee mortality and levels of carbon dioxide (CO2) and oxygen (O2) in the bee cluster when kept under a simulated winter condition at 5°C. The second experiment, used colonies from selected bees (n=10) and unselected bees (n=12) that were exposed to either standard ventilation (14.4 liter/min per hive) or restricted ventilation (0.24 liter/min per hive, in a Plexiglas ventilation chamber) during a 16-d treatment period to assess the influence of restricted air flow on winter mortality rates of varroa mites and honey bees. Experiment 2 was repeated in early, mid-, and late winter. The first experiment showed that under unrestricted ventilation with CO2 concentrations averaging <2% there was no correlation between CO2 and varroa mite mortality when colonies were placed under low temperature. CO2 was negatively correlated with O2 in the bee cluster in both experiments. When ventilation was restricted, mean CO2 level (3.82±0.31%, range 0.43–8.44%) increased by 200% relative to standard ventilation (1.29±0.31%; range 0.09–5.26%) within the 16-d treatment period. The overall mite mortality rates and the reduction in mean abundance of varroa mite over time was greater under restricted ventilation (37±4.2%) than under standard ventilation (23±4.2%) but not affected by stock of bees during the treatment period. Selected bees showed overall greater mite mortality relative to unselected bees in both experiments. Restricting ventilation increased mite mortality, but did not affect worker bee mortality relative to that for colonies under standard ventilation. Restricted ventilation did not affect the overall level of Nosema compared with the control. However, there was an interaction between stock, season, and time of the trial. Unselected stock showed an increase in Nosema over time in the late winter trial that did not occur in the selected stock. In conclusion, these findings suggested that restricted ventilation has potential to suppress varroa mite in overwintering honey bee colonies via a low-cost and environmentally friendly measure.
Utilization of timed virus acquisition access probes in studies of plum pox virus (PPV) transmission by aphids demonstrated that endemic species transmitted the virus readily from plum, Prunus domestica (L.) Batsch; peach, P. persica (L.); or dwarf flowering almond, P. glandulosa Thunberg., to peach seedlings. The green peach aphid, Myzus persicae (Sulzer), was shown to be the most efficient vector. Acquisition of virus by green peach aphids from infected peach leaves resulted in 18–28% infected peach seedlings, while aphids previously fed on infected leaves of plum transferred virus to 36% of peach seedlings. Although the spirea aphid, Aphis spiraecola (Patch), was a less efficient vector than M. persicae it is perhaps more important for the spread of PPV due to its greater abundance and occurrence earlier in the season when peach trees are thought to be more susceptible to infection. Virus transmission rates varied depending on the virus source and healthy test plant species. In contrast to many previous studies, aphid inoculation of the experimental host Nicotiana benthamiana Domin occurred at a low rate, never exceeding 4%. Acquisition of PPV by M. persicae from infected peach fruit was greatly reduced compared with acquisition from leaves. The results of this research indicate that the Ontario isolate of PPV-D is readily transmissible by aphids to peach and natural spread of the virus needs to be considered in future management or eradication programs.
The psyllid species Cacopsylla melanoneura (Förster) and Cacopsylla picta (Förster) are vectors of ‘Candidatus Phytoplasma mali’, the causal agent of apple proliferation, one of the economically most important apple diseases in Europe. Both vectors are present in apple orchards of South Tyrol and Trentino provinces in Northern Italy. As no direct treatment of the disease is possible, monitoring of the psyllids provides information about the vector presence in the orchards and enables targeted control. Thus, fast and reliable identification of the various psyllids occurring in the apple orchards is required. Morphological differentiation is problematic due to extensive resemblance of some psyllid species especially among females and is error-prone for nymphs. Here we present a rapid and cost-effective polymerase chain reaction-restriction fragment length polymorphism method based on the cytochrome c oxidase subunit I region for the molecular identification of the vector species as well as eight further Cacopsylla species present in the orchards. This method was verified through 98.9% consensus with morphologically identified males, through sequencing and subsequent phylogenetic analysis. In case of doubtful morphological identification of females, the method was able to provide a refined species assignment and could also remarkably facilitate the identification of nymphs.
Plutella xylostella granulovirus (PxGV) and Bacillus thuringiensis (Bt) are both entomopathogens to the diamondback moth, Plutella xylostella (L.). The purpose of the present study was to measure the effect of the combination of PxGV and Bt at sublethal dosages on the development and mortality of diamondback moth in a laboratory setting. Bt and PxGV exhibited synergistic effect on diamondback moth larval mortality and effectively controlled diamondback moth populations with low dose combination treatment. The combination of three parts per million Bt and 1.3 × 103 occlusion bodies per milliliter of PxGV revealed a higher larval mortality compared with the treatment of Bt or PxGV alone. Combination of Bt and PxGV at sublethal concentrations also increased larval duration, reduced oviposition and decreased adult longevity remarkably, resulting in the lowest population trend index among the treatments. The results suggested that the combination of Bt and PxGV at sublethal dosages might provide a valuable way to improve the control efficacy of diamondback moth compared with treatment of Bt or PxGValone.
Thermal death kinetics of Conogethes punctiferalis (Guenée) (Lepidoptera: Pyralidae) at different life stages, heating rate, and temperature is essential for developing postharvest treatments to control pests in chestnuts. Using a heating block system (HBS), the most heat-tolerant life stage of C. punctiferalis and the effects of heating rate (0.1, 0.5, 1, 5, and 10°C/min) on insect mortality were determined. The thermal death kinetic data of fifth-instar C. punctiferalis were obtained at temperatures between 44 and 50°C at a heating rate of 5°C/min. The results showed that the relative heat tolerance of C. punctiferalis was found to be fifth instars > pupae > third instars > eggs. To avoid the enhanced thermal tolerance of C. punctiferalis at low heating rates (0.1 or 0.5°C/min), a high heating rate of 5°C/min was selected to simulate the fast radio frequency heating in chestnuts and further determine the thermal death kinetic data. Thermal death curves of C. punctiferalis followed a 0th-order kinetic reaction model. The minimum exposure time to achieve 100% mortality was 55, 12, 6, and 3 min at 44, 46, 48, and 50°C, respectively. The activation energy for controlling C. punctiferalis was 482.15 kJ/mol with the z value of 4.09°C obtained from the thermal death—time curve. The information provided by thermal death kinetics for C. punctiferalis is useful in developing effective postharvest thermal treatment protocols for disinfesting chestnuts.
Male adult navel orangeworm, Amyelois transitella (Walker), were irradiated using a laboratory scale x-ray irradiation unit to determine the required dose for complete egg sterility of mated female moths and inherited sterility of F1 and F2 generations. Adult male A. transitella were irradiated in two separate experiments at 100–300Gy and 50–175Gy. Mating frequency, fecundity, and fertility of normal females crossed with irradiated parental males was compared with the mating of nonirradiated moths. Mating frequency was 100% for females crossed with nonirradiated control males. At male treatment doses of ≥150Gy the percentage of females found unmated increased, while multiple-mated females decreased. Female fecundity was not affected while fertility was affected in a dose-dependent relationship to exposure of parental males to x-ray irradiation. Embryonic development of eggs to the prehatch stage and egg eclosion did not occur at radiation doses ≥125Gy. Emergence of F1 adults was low and occurred only for progeny of parental males exposed to doses ≤100Gy, with no emergence at ≥125Gy. Though fecundity appeared similar for control and irradiated F1 females, no F2 eggs hatched for the test exposures of 50–100Gy. Based on our results, a dose of ≥125Gy had efficacy in inducing both primary parental sterility in treated male moths and inherited sterility in F1 male and female moths. Results suggest that A. transitella might be considered a candidate for the sterile insect technique using adults irradiated at these relatively low x-ray exposure doses.
J.-F. Vayssières, M. De Meyer, I. Ouagoussounon, A. Sinzogan, A. Adandonon, S. Korie, R. Wargui, F. Anato, H. Houngbo, C. Didier, H. De Bon, G. Goergen
We report the results of a large-scale (six orchards) and long-term (5-yr) study on seasonal population fluctuations of fruit flies (Diptera Tephritidae) in mango (2005–2009) and cashew (2007–2009) orchards in the Borgou Department, Benin.
During the five consecutive years of mango fruit fly monitoring, 25 tephritid species were captured including three species of Bactrocera, 11 of Ceratitis, and 11 of Dacus, which is represented by 2,138,150 specimens in mango orchards. We observed significant differences in Bactrocera dorsalis (Hendel) counts between “high” and “low” mango production years from 2005 to 2008 but not in Ceratitis cosyra (Walker) counts. The native species, C. cosyra, the most abundant species during the dry season, peaked beginning of May, while the exotic species, B. dorsalis, the most abundant species during the rainy season, peaked in June. Preliminary results underlined the role of nine species of wild hosts and seven species of cultivated ones around mango orchards that played an important role in maintaining B. dorsalis in this Sudan zone all year round. The presence of C. cosyra stretched over 9 mo.
During the first 14 wk of tephritid monitoring on cashew orchards situated near mango orchards, most flies (62%) were captured in traps positioned in cashew orchards, showing the strong interest of an early fly control on cashew before the mango season. According to these results, in the Sudan zone, effective and compatible control methods as proposed by the IPM package validated by the West African Fruit Fly Initiative project against mango fruit flies are proposed for a large regional tephritid control program in same zones ofWest Africa.
Knowledge on movement and spatial patterns of insect pest populations among preferred hosts aids in the development of effective pest management strategies. In this study, we quantified the spatiotemporal dynamics of the invasive brown marmorated stink bug, Halyomorpha halys (Stål 1855), in relation to field corn, Zea mays L., and soybean, Glycine max (L.), crop phenology.We also examined the potential role of corn as a source of stink bugs in adjacent soybean. The highest density of stink bugs in each crop coincided with blister to milk-dough stages in corn (R2–R3/R4), and beginning seed to full seed (R5–R6) stages in soybean. In entire fields of adjacent corn and soybean, H. halys was found in very low density (<0.5/m2) or absent beyond 25m from the field edge. Inverse distance weighted interpolations of H. halys densities suggest potential dispersal of H. halys, particularly adults and large nymphs, from corn into soybean, coinciding with the end of dough stage in corn and beginning of soybean seed development stage. These findings have important implications for managing H. halys through location and timing of scouting efforts, consideration of crop arrangement, and decisions on management interventions. Repeated scouting of field corn to assess H. halys densities, particularly from blister stage onwards, could inform decisions on management interventions for preventing or mitigating H. halys colonization into soybean. Where H. halys is an economic problem, reducing the extent of boundary shared between corn and soybean could reduce dispersal into soybean.
Spodoptera litura (F.), an important polyphagous insect pest, attacks ca. 300 economic crops in dozens of countries. Investigations into its growth and development performance on different host plants can provide an understanding of the potential for increase of S. litura population in the field. We measured the development time, body weight, and head capsule width of S. litura larvae reared on cabbage, taro, peanut, and sesbania, a green manure. Larvae reared on cabbage ingested a significantly higher amount of protein and completed the immature stages in a shorter period than those reared on the other three plants. The relationship between head capsule width and larval instars on these four crops fitted well with Dyar's rule, and the Dyar's ratios ranged from 1.4554 to 1.6786, although a few supernumerary instar individuals on sesbania, peanut, and taro showed lower ratios (1.0103 to 1.1330). The head capsule width among cohorts fed on different host plants varied significantly and overlapped between late instars, which could lead to a misjudgment of instar stage in the field. The growth index of S. litura on cabbage was significantly higher than on the other host plants. Larvae fed on sesbania showed the highest feeding index and a better growth index than on taro and peanut. We therefore suggest that the area-wide pest management against S. litura should take into consideration its occurrence on sesbania in intercropping seasons. Additionally, the effective management of this pest during cropping windows between all these four plants should not be ignored.
The climate warming trend appears to be evident with an increasing frequency of drought events in Shaanxi Province of China, which may have contributed to an increase in outbreaks of the English grain aphid, Sitobion avenae (Fabricius). To explore the potential effects of water-deficit stress on aphid outbreak risks, clones of S. avenae were collected from semi-arid and moist areas of Shaanxi. The life histories of collected clones were then compared on wheat under well-watered and moderately water-stressed conditions in the laboratory. Our results demonstrated that semi-arid area clones of S. avenae had longer developmental times, shorter reproductive times, lower fecundities, and lower net reproductive rates compared with moist area clones. Age-specific reproductive rates of moist area clones tended to be higher than those of semi-arid area clones. Significant differences between semi-arid and moist area clones were found for the survival functions when tested under water-stressed conditions, and semiarid area clones tended to have a lower survival rate than moist area clones throughout their lives. “Population origin” (i.e., semi-arid and moist area clones) and “clone” together explained 62.74–96.56% of the total variance of tested life-history traits, suggesting the genetic basis for differentiation of clones from both areas. Significant differences in correlations, and selection differentials and gradients of life-history traits were also found between clones from both areas, providing further evidence of genetic basis for the life-history differentiation between them. Divergence between clones from both areas and its implications for S. avenae outbreaks are discussed.
Crowding conditions of larvae may have a significant impact on commercial production efficiency of some insects, such as Tenebrio molitor L. (Coleoptera: Tenebrionidae). Although larval densities are known to affect developmental time and growth in T. molitor, no reports were found on the effects of crowding on food utilization. The effect of larval density on food utilization efficiency of T. molitor larvae was studied by measuring efficiency of ingested food conversion (ECI), efficiency of digested food conversion (EDC), and mg of larval weight gain per gram of food consumed (LWGpFC) at increasing larval densities (12, 24, 36, 48, 50, 62, 74, and 96 larvae perdm2) over four consecutive 3-wk periods. Individual larval weight gain and food consumption were negatively impacted by larval density. Similarly, ECI, ECD, and LWGpFC were negatively impacted by larval density. Larval ageing, measured as four consecutive 3-wk periods, significantly and independently impacted ECI, ECD, and LWGpFC in a negative way. General linear model analysis showed that age had a higher impact than density on food utilization parameters of T. molitor larvae. Larval growth was determined to be responsible for the age effects, as measurements of larval mass density (in grams of larvae per dm2) had a significant impact on food utilization parameters across ages and density treatments (in number of larvae per dm2). The importance of mass versus numbers per unit of area as measurements of larval density and the implications of negative effects of density on food utilization for insect biomass production are discussed.
The parasitic wasp Eretmocerus mundus (Mercet) is an important natural enemy of the widespread key pest Bemisia tabaci (Gennadius). The toxicity of 11 modern insecticides applied at their maximum field recommended rate in Spain was tested in two life stages of E. mundus: adults and mummies. Laboratory and persistence tests were conducted and effects assessed not only in terms of mortality but on reproductive performance as well. Some insecticides caused the same effect to both life stages: flubendiamide, methoxyfenozide, spiromesifen, and flonicamid were harmless, while spinosad and sulfoxaflor were harmful. The last two insecticides cannot be used jointly with E. mundus under any condition because they were highly persistent. The rest of tested insecticides (spirotetramat, metaflumizone, deltamethrin, abamectin, and emamectin) caused some direct mortality to one or both life stages and/or affected reproduction of the parasitic wasp and their harmful effect in the field ranged from short lived (metaflumizone and spirotetramat) to slightly persistent (emamectin) and to moderately persistent (abamectin and deltamethrin). Therefore, they could be recommended for use in integrated pest management programs together with the natural enemy if appropriate safety intervals after insecticide application are observed.
The use of synthetic acaricides for management of pest mites may alter the efficacy of the ectoparasitoid Tamarixia radiata (Waterston) in biological control of Diaphorina citri Kuwayama, the vector of the bacteria associated with huanglongbing (HLB) in citrus orchards.We evaluated the toxicity of 16 acaricides that are recommended for the control of citrus-pest mites to T. radiata. Acrinathrin, bifenthrin, carbosulfan, and fenpropathrin caused high acute toxicity and were considered harmful (mortality >77%) to T. radiata. Abamectin, diflubenzuron, etoxazole, fenbutatin oxide, fenpyroximate, flufenoxuron, hexythiazox, propargite, spirodiclofen, and sulfur caused low acute toxicity and affected the parasitism rate and emergence rate of adults (F1 generation), and were considered slightly harmful to T. radiata. Dicofol and pyridaben did not affect the survival and action of the ectoparasitoid, and were considered harmless. In addition to its acute toxicity, carbosulfan caused mortality higher than 25% for >30 d after application, and was considered persistent. Acrinathrin, bifenthrin, fenpropathrin, fenpyroximate, propargite, and sulfur caused mortalities over 25% until 24 d after application and were considered moderately persistent; abamectin was slightly persistent, and fenbutatin oxide was short lived. Our results suggest that most acaricides used to control pest mites in citrus affect the density and efficacy of T. radiata in the biological control of D. citri. However, further evaluations are needed in order to determine the effect of these products on this ectoparasitoid under field conditions.
Bactericera cockerelli (Sulc) (Hemiptera: Triozidae) is one of the most economically important pests of potato, tomato, and peppers in Central America, Mexico, the United States, and New Zealand. Its control is based on the use of insecticides; however, recently, the potential of the eulophid parasitoid Tamarixia triozae (Burks) (Hymenoptera: Eulophidae) for population regulation has been studied. Because T. triozae is likely to be exposed to insecticides on crops, the objective of this study was to explore the compatibility of eight insecticides with this parasitoid. The toxicity and residual activity (persistence) of spirotetramat, spiromesifen, beta-cyfluthrin, pymetrozine, azadirachtin, imidacloprid, abamectin, and spinosad against T. triozae adults were assessed using a method based on the residual contact activity of each insecticide on tomato leaf discs collected from treated plants growing under greenhouse conditions. All eight insecticides were toxic to T. triozae. Following the classification of the International Organization of Biological Control, the most toxic were abamectin and spinosad, which could be placed in toxicity categories 3 and 4, respectively. The least toxic were azadirachtin, pymetrozine, spirotetramat, spiromesifen, imidacloprid, and beta-cyfluthrin, which could be placed in toxicity category 2. In terms of persistence, by day 5, 6, 9, 11, 13, 24, and 41 after application, spirotetramat, azadirachtin, spiromesifen, pymetrozine, imidacloprid, beta-cyfluthrin, abamectin, and spinosad could be considered harmless, that is, placed in toxicity category 1 (<25% mortality of adults). The toxicity and residual activity of some of these insecticides allow them to be considered within integrated pest management programs that include T. triozae.
The Mexican rice borer, Eoreuma loftini (Dyar) (Lepidoptera: Crambidae) is an invasive stem borer of sugarcane, Saccharum spp., and sorghum, Sorghum bicolor (L.), and poses a threat against the production of dedicated bioenergy feedstocks in the U.S. Gulf Coast region. A 2-yr field study was conducted in Jefferson County, TX, to evaluate yield losses associated with E. loftini feeding on bioenergy and conventional cultivars of sugarcane and sorghum under natural and artificially established E. loftini infestations. Bioenergy sugarcane (energycane) ‘L 79-1002' and ‘Ho 02-113' and sweet sorghum ‘M81E' exhibited reduced E. loftini injury; however, these cultivars, along with high-biomass sorghum cultivar ‘ES 5140', sustained greater losses in fresh stalk weight. Negative impacts to sucrose concentration from E. loftini injury were greatest in energycane, high-biomass sorghum, and sweet sorghum cultivars. Even under heavy E. loftini infestations, L 79-1002, Ho 02-113, and ‘ES 5200' were estimated to produce more ethanol than all other cultivars under suppressed infestations. ES 5200, Ho 02-113, and L 79-1002 hold the greatest potential as dedicated bioenergy crops for production of ethanol in the Gulf Coast region; however, E. loftini management practices will need to be continued to mitigate yield losses.
Spodoptera frugiperda, the fall armyworm, is a major economic pest throughout the Western Hemisphere of corn (maize), cotton, sorghum, and a variety of agricultural grasses and vegetable crops. Studies in the United States, the Caribbean, and Brazil demonstrated the existence of two subpopulations (previously designated “host strains”) that differ in their choice of plant host. Specifically, the corn strain is preferentially found in corn and sorghum, while the rice strain is dominant in rice, turf grass, and alfalfa. However, inconsistent results were reported in surveys of fall armyworm in Argentina, with some indicating that the host plant preferences of the two strains might be compromised or even nonexistent. If correct, this would complicate efforts to control this pest by considerably expanding the range of habitats that would have to be considered as potential sources for fall armyworm infestations in specific crops. A reexamination of Argentine fall armyworm, this time with field collections rather than the laboratory colonies used in previous studies, confirmed the existence of the two strains and their host preferences. Specifically, the corn strain was consistently the majority population infesting corn and was usually so in sorghum, while the rice strain was predominant in pasture/turf grasses and alfalfa. The one outlier was a collection from rice, which had a corn strain majority. Overall, the data were generally consistent with strain behaviors observed in other areas of the Western Hemisphere.
Wheat stem sawfly (WSS), Cephus cinctus Norton (Hymenoptera: Cephidae), has recently emerged as a key pest of wheat (Triticum aestivum L.) in the Great Plains and Canadian provinces. The expanding impact of WSS has caused considerable economic losses to wheat production. Solid-stem varieties of wheat remain the only effective measure of suppression of WSS, and the goal of this research was to test whether five solid- and hollow-stem varieties of winter and spring wheat reduce survival of WSS in South Dakota.We reported that solid-stem varieties had significantly lower numbers of WSS larvae, and this effect was especially evident when WSS infestation rates exceeded 15%. We also observed that the yield of solid-stem varieties was significantly lower than hollow-stem varieties when the abundance of WSS was low, but not when populations of WSS were relatively high. We did not observe consistent differences in grain quality between solid- and hollow-stem varieties, however, and in case of protein levels of grain, solid-stem wheat varieties performed better than hollow-stem wheat. We conclude that solidstem varieties of wheat appear to effectively suppress WSS survival, and reduced yield of these varieties is less apparent when populations of C. cinctus are high enough to affect the yield of hollow-stem wheat. This is the first report to describe the effectiveness of solid-stem varieties of wheat on WSS in South Dakota. More research in the state is necessary before more robust conclusions can be drawn.
Euschistus serous (Say), Nezara viridula (L.), and Chinaoia hilaris (Say) (Hemiptera: Pentatomidae) are economic pests of cotton in the coastal plain of the southeastern United States. The objective of this 2-yr study was to determine the ability of trap cropping systems, pheromone-baited stink bug traps, and a synthetic physical barrier at the peanut-to-cotton interface to manage stink bugs in cotton. The physical barrier was the most effective management tactic. Stink bug density in cotton was lowest for this treatment. In 2010, boll injury was lower for the physical barrier compared to the other treatments except for soybean with stink bug traps. In 2011, boll injury was lower for this treatment compared to the control. Soybean was an effective trap crop, reducing both stink bug density in cotton and boll injury regardless if used alone or in combination with either stink bug traps or buckwheat. Incorporation of buckwheat in soybean enhanced parasitism of E. servus egg masses by Telenomus podisi Ashmead in cotton. The insertion of eyelets in the lid of the insect-collecting device of a stink bug trap allowed adult stink bug parasitoids, but not E. servus, to escape. Stand-alone stink bug traps were not very effective in deterring colonization of cotton by stink bugs or reducing boll injury. The paucity of effective alternative control measures available for stink bug management justifies further full-scale evaluations into these management tactics for control of these pests in crops.
The invasion by Halyomorpha halys (Stål) and an increasing abundance of native Pentatomidae pose a threat to soybean, Glycine max (L.) Merrill, production in northern states. A risk assessment framework was used to provide an initial assessment of the risk of Pentatomidae affecting soybean production in northern states. A caged field study was performed over two years to assess the response of soybean to H. halys feeding. Cages placed over R4 soybean were infested with 0, 1, 2, 4, or 8 fourth-instar H. halys nymphs per 0.3 row-m, and the insects were allowed to feed for 15 to 16 days. Feeding by H. halys on soybean affected yield components, maturity, and quality (i.e., seed injury). Season-long monitoring of soybean fields was performed via sweep net sampling to assess the likelihood of herbivorous Pentatomidae occurring on soybean during plant growth stages susceptible to feeding injury. Adults of herbivorous species were collected at low densities in fields in mid- to late July before collection of herbivorous nymphs. Herbivorous nymphs were first collected in the R3 and R4 soybean growth stages and their abundance peaked during the R6 soybean growth stage. This preliminary assessment indicates that if populations of exotic and native herbivorous Pentatomidae continue to increase in abundance, they will pose a threat to northern soybean production.
Protection of green ash trees (Fraxinus pennsylvanica Marshall) from the emerald ash borer (EAB), Agrilus planipennis Fairmaire, by soil applications of neonicotinoids (imidacloprid, clothianidin, and dinotefuran) was tested at five locations between 2005 and 2013. Application rate and spring versus fall application dates were evaluated in tests with neighborhood street trees and in one plantation of 65 ash trees. Insecticide treatments of ash trees at all five sites were initiated as the leading edge of the EAB invasion began to kill the first ash trees at each location. Trees were treated and evaluated at each site for 4 to 7 yr. Spring applications of imidacloprid were more efficacious than fall applications. Application rates of 0.8 g a.i./cm dbh or greater per year gave a higher level of protection and were more consistent than rates of 0.56 g a.i./cm dbh per year or less. The number of years between the first observation of canopy loss due to EAB and death of most of the control trees varied from three to seven years among test sites, depending on how many non-treated ash trees were nearby.
In north-central Georgia, 13 species of woodboring beetles (Coleoptera: Cerambycidae: Cerambycinae) were attracted to multiple-funnel traps baited with ethanol and one of the following pheromones: (1) racemic 3-hydroxyhexan-2-one; (2) racemic 3-hydroxyoctan-2-one; and (3) syn-2,3-hexanediol. The following species were attracted to traps baited with ethanol and 3-hydroxyhexan-2-one: Anelaphus pumilus (Newman), Eburia quadrigeminata (Say), Euderces pini (Olivier), Knulliana cincta (Drury), Neoclytus mucronatus (F.), Neoclytus scutellaris (Olivier), and Xylotrechus colonus (F.). Clytus marginicollis Castelnau & Gory, and Anelaphus parallelus (Newman) were attracted to traps baited with ethanol and 3-hydroxyoctan-2-one, whereas traps baited with ethanol and syn-2,3-hexanediol were attractive to Anelaphus villosus (F.), A. parallelus, Neoclytus acuminatus (F.), Neoclytus jouteli jouteli Davis, and Megacyllene caryae (Gahan). Ethanol enhanced catches of seven cerambycid species in traps baited with syn-2,3-hexanediol and 3,2-hydroxyketones. Catches of bark and ambrosia beetles (Curculionidae: Scolytinae) in ethanol-baited traps were largely unaffected by the addition of syn-2,3-hexanediol and 3,2-hydroxyketone lures, except for two species. The mean catches of Hypothenemus rotundicollis Wood & Bright and Dryoxylon onoharaensum (Murayama) in ethanol-baited traps increased and decreased, respectively, with the addition of racemic 3-hydroxyoctan-2-one. Traps baited with ethanol and syn-2,3-hexanediol were attractive to Xylobiops basilaris (Say) (Bostrichidae) and Chariessa pilosa (Forster) (Cleridae), whereas Temnoscheila virescens (F.) (Trogossitidae) were attracted to traps baited with ethanol and 3-hydroxyhexan-2-one. The assassin bug, Apiomerus crassipes (F.) (Hemiptera: Reduviidae), was attracted to traps baited with ethanol and 3,2-hydroxyketones.
The brown-winged green bug, Plautia stali Scott, mainly reproduces on Japanese cedar or cypress cones in Japanese plantation forests during summer and autumn. It often depletes its food sources in forest habitats and moves to cultivated crops in large numbers. To establish an easy method for assessing the risk of fruit orchard infestation by P. stali, we conducted a 3-yr field survey that monitored the attraction of bugs to the synthetic P. stali aggregation pheromone using a sticky trap.We used a morphological indicator, variable body size depending on food intake, to estimate the nutritional status in nymphs, which showed that nymphs attracted to the synthetic pheromone were starving. Comparisons between increasing changes in the number of stylet sheaths left on the cones by P. stali and the number of trapped nymphs show that monitoring nymphs with the pheromone-baited sticky trap is useful for inferring conditions regarding food resources in forest habitats. The trend toward trapping second instars can provide a timely overview of resource competition for cones. Trapping middle-to-late (third—fifth) instars is a warning that the cones are finally depleted and that there is a high probability that adults will leave the forests and invade the orchards. In addition, trends in trapping adults suggest that there is a potential risk of orchard infestation by the pest and predict the intensity and period of the invasion. The pheromone-baited sticky trap is an easy but useful survey tool for predicting P. stali orchard infestations.
Colorado potato beetle, Leptinotarsa decemlineata (Say), is an important pest of potato throughout the world. Here, the effects of six potato cultivars including ‘Arinda,’ ‘Sprit,’ ‘Markiez,’ ‘Lotta,’ ‘Santae,’ and ‘Agria’ were studied on nutritional indices, digestive enzymes, and some components involved in intermediary metabolism of L. decemlineata. Nutritional indices of the larvae and the adults were significantly different followed by feeding on various potato cultivars. The individuals fed on Agria showed the highest activity of digestive proteases although cathepsin B demonstrated same Activity on Santae and Lotta. The highest activity of α-amylase was found in the larvae fed on Arinda, but the adults demonstrated the highest amylolytic activities on Santae and Agria. Both larvae and adults of L. decemlineata fed on Santae revealed the highest α- and β-glucosidase activities. No significant differences were found in lipase activity of larvae, but the highest lipase activity was found in the adults fed on Santae. The highest activities of transaminases were found in the larvae and adults fed on the Agria except for γ-glutamyl transferase. In case of aldolase, the highest activities were observed in the larvae and adults fed on Santae and Sprit. The highest activities of lactate dehydrogenase were obtained in the larvae and adults fed on Santae. The highest amount of low-density lipophorin was measured in both individuals fed on Santae. There were no significant differences in high-density lipophorin amount of adults, but the highest value was found in the larvae fed on Agria. The lowest amounts of protein and triglyceride were observed in both individuals fed on Santae and Agria, respectively. These results revealed Santae is the most suitable cultivar for L. decemlineata based on digestion and intermediary metabolism findings, but Lotta is an unsuitable cultivar and could be considered for integrated pest management.
A 2-yr survey was conducted on golf courses in South Carolina to 1) document the species richness and seasonal activity of Scarabaeoidea; 2) assess any species compositional differences among three trap types (ultraviolet light, unbaited flight-intercept, and unbaited pitfall); and 3) identify any dominant taxa in each trap type. A total of 74,326 scarabaeoid beetles were captured, of which 77.4% were Aphodiinae (not identified to species). The remaining specimens belong to 104 species in 47 genera and 6 families. The most abundant species were Cyclocephala lurida Bland, Dyscinetus morator (F.), Euetheola humilis (Burmeister), Hybosorus illigeri Reiche, and Maladera castanea (Arrow). In all trap types, >90% of all specimens and taxa were collected between April and August. Ultraviolet light traps collected ∼94% of total specimens consisting of 83 taxa (of which 51 were unique to this trap type), whereas flight-intercept traps captured ∼2% of all specimens representing 53 taxa (18 of which were unique), and pitfall traps captured ∼4% of all specimens representing 15 taxa (no unique species; all species also captured by ultraviolet light traps). Indicator species analysis identified 2–3 and 10–13 taxa that were most frequently collected by flight-intercept and ultraviolet light traps, respectively. Flight-intercept traps complemented ultraviolet light traps by capturing more species of dung and carrion beetles and diurnal phytophagous scarab beetles. Results suggested that a similar survey for domestic or exotic scarabaeoid beetles in turfgrass systems should be conducted between April and August using ultraviolet light and flight-intercept traps at 13–58 sites.
The citrophilus mealybug, Pseudococcus calceolariae (Maskell), is an important pest of fruit crops in many regions of the world. Recently, its sex pheromone has been identified and synthesized. We carried out field experiments with the goal of developing monitoring protocols for P. calceolariae using pheromone-baited traps. Traps checked hourly for 24 hours showed a distinct diel pattern of male flight, between 18:00 and 21:00 h. The presence of unnatural stereoisomers did not affect trap captures, with isomeric mixtures capturing similar amounts of males as the biological active isomer. Dose of isomeric mixture pheromone (0–100 µg) had a nonlinear effect on male captures, with 10, 30, and 50 pg capturing similar amounts. The effective range of pheromone traps was determined by placing traps at different distances (15, 40, and 80 m) from an infested blueberry field, loaded with 0, 1 and 25 pg of the pheromone. For all distances, 25 µg dose captured more males, and was highly attractive up to 40 m. There was a significant effect of lure age on male captures (0–150 d), with similar amount of males captured up to 90-day-old lure, and lower captures in the 150-day-old lure compared with fresh ones. We found significant positive correlations between P. calceolariae males caught in pheromone traps with female abundance and fruit infestation at harvest. Our results show the usefulness of P. calceolariae pheromones for monitoring at field level and provide information for the design of monitoring protocols.
A field study was initiated in 2009 with 0.5% novaluron the BASF Advance Termite Bait System, which was 100% effective in controlling Reticulitermes sp. Holmgren and Coptotermes formosanus Shiraki infestations on 11 structures in the Texas City, TX area. Stations with inspection cartridges (cellulose tablets) and monitoring bases (southern yellow pine) and independent monitoring devices were installed in an alternating pattern around each structure and were inspected every 30 d postinstallation. When subterranean termite activity was confirmed on the inspection cartridge or the monitoring base, the inspection cartridge was removed and replaced with a bait cartridge containing 0.5% novaluron insecticide on a proprietary matrix (124 g/cartridge) in a station. Once the novaluron-treated bait was inserted, inspections of that station were made on a 4-mo cycle until no termite activity was observed. The mean time to achieve control of the subterranean termites on the structures was 10.5 mo post initial installation of bait. Mean time to achieve control of the termites on the structures after the baits were installed was 5.4 mo. Control of the termites on the structures required consumption of a mean of 1.3 bait cartridges (166.2 g) of 0.5% novaluron bait matrix per structure. These results indicate that the baits with 0.5% novaluron were effective in controlling termites on the structures used in this study.
Soil-applied liquid termiticides are the most common control measure for subterranean termites. Characteristics unique to insecticidal chemistries such as repellency, toxicity, and time between contact and mortality, influence the interaction of termites with treated soil and overall treatment success. Two different treated-tunnel bioassays were used to evaluate the behavioral impacts and mortality of termites from treatment with chlorantraniliprole (the active ingredient in Altriset® termiticide) to existing, mature tunnels. Termites that were provided constant access to a 10-cm-long mature tunnel within soil treated with 5 or 50 ppm chlorantraniliprole were not repelled by the treatment and began exhibiting slower, uncoordinated movement, and cessation of tunneling and feeding in as little as 1 h after access. Termites provided access for 7, 14, or 21 d to previously constructed tunnels recently treated with 50 ppm chlorantraniliprole exhibited complete or near complete mortality by 28 d. The second bioassay design resembled a more typical field situation with a 40-cm-long mature tunnel and termites allowed access for a maximum of 5 min. Termites collected after just 5 min of access to the previously constructed tunnels recently treated with 50 ppm chlorantraniliprole exhibited similar symptomology within an hour followed by complete mortality at 18 d after exposure. These test designs simulate what occurs in the soil around an infested structure at the time of treatment. Results from these evaluations suggest that termites readily crawl through chlorantraniliprole-treated mature tunnels, rapidly lose ability to feed, and acquire a lethal dose from brief exposures.
Transgenic crops that produce insecticidal toxins derived from the bacterium Bacillus thuringiensis (Bt) are widely planted to manage pest insects. One of the primary pests targeted by Bt corn in the United States is western corn rootworm, Diabrotica virgifera virgifera LeConte (Coleoptera: Chrysomelidae). Cry3Bb1 corn for management of western corn rootworm was commercialized in 2003, and beginning in 2009, populations of western corn rootworm with field-evolved resistance to Cry3Bb1 corn were found in Iowa. Here we quantify the magnitude, inheritance, and fitness costs of resistance to Cry3Bb1 corn in two strains (Hopkinton and Cresco) derived from field populations that evolved resistance to Cry3Bb1 corn. For Hopkinton, we found evidence for complete resistance to Cry3Bb1 corn and nonrecessive inheritance. Additionally, no fitness costs of Cry3Bb1 resistance were detected for Hopkinton. For Cresco, resistance was incomplete and recessive, and we detected fitness costs affecting developmental rate, survival to adulthood, and fecundity. These results suggest that variation may exist among field populations in both the inheritance and accompanying fitness costs of resistance. To the extent that field populations exhibit nonrecessive inheritance and a lack of fitness cost, this will favor more rapid evolution of resistance than would be expected when resistance is functionally recessive and is accompanied by fitness costs.
Glucose-6-phosphate isomerase (G6PI) and UDP-N-acetylglucosamine pyrophosphorylase (UAP), two key components in the chitin biosynthesis pathway, are critical for insect growth and metamorphosis. In this study, we identified the genes BdG6PI and BdUAP from the oriental fruit fly, Bactrocera dorsalis (Hendel). The open reading frames (ORFs) of BdG6PI (1,491 bp) and BdUAP (1,677 bp) encoded 496 and 558 amino acid residues, respectively. Multiple sequence alignments showed that BdG6PI and BdUAP had high amino acid sequence identity with other insect homologues. Quantitative real-time polymerase chain reaction (qPCR) analysis indicated that BdG6PI was mainly expressed in the early stages of third-instar larvae and adults, while significantly higher expression of BdUAP was observed in adults. Both transcripts were expressed highly in the Malpighian tubules, but only slightly in the tracheae. The expression of both BdG6PI and BdUAP was significantly up-regulated by 20-hydroxyecdysone exposure and down-regulated by starvation. Moreover, injection of double-stranded RNAs of BdG6PI and BdUAP into third-instar larvae significantly reduced the corresponding gene expressions. Additionally, silencing of BdUAP resulted in 65% death and abnormal phenotypes of larvae, while silencing of BdG6PI had a slight effect on insect molting. These findings provide some data on the roles of BdG6PI and BdUAP in B. dorsalis and demonstrate the potential role for BdUAP in larval—pupal transition.
The insect family Cicadellidae includes economically important vectors of plant pathogens. Hishimonus sellatus (Uhler) transmits jujube witches'-broom (JWB). Currently, H. sellatus and Hishimonus lamellatus Cai et Kuoh are observed to co-occur at the same locality on jujube. H. lamellatus is now suspected to be a JWB vector. As such, correct identification of Hishimonus species present in vineyards is essential for epidemiological surveys. However, traditional identification of Hishimonus by morphology is limited to the adult male. We provide a comprehensive description of morphological and molecular tools for discriminating between H. sellatus and H. lamellatus, for use in identification and monitoring of the two Hishimonus species and studies of their plant hosts. A rapid and inexpensive method is introduced to identify H. sellatus and H. lamellatus occurring in jujube orchards. This method is based on amplification of mitochondrial cytochrome oxidase I (COI) gene, using PCR with multiplexed, species-specific primers. The reliability of this new method has been tested on different populations from different sites in Beijing region of China.
European gypsy moth populations (Lymantria dispar L.) are well established and a proven destructive force in hardwood trees throughout the United States and Canada. Introduction of the exotic Asian gypsy moth into North America would be even more impactful, as Asian gypsy moth populations have wider host ranges, and are capable of naturally dispersing more rapidly due to female flight ability. To support early detection and exclusion of Asian gypsy moth, the U.S. Department of Agriculture (USDA) uses molecular techniques to screen moths trapped in North America for evidence of common Asian genotype. In order to strengthen U.S. domestic capacity to screen moths quickly and efficiently, we report a real-time PCR assay for this pest. A probe system using TaqMan 5' nuclease chemistry is reported for detection of an allele associated with common Asian gypsy moth genotypes. The targeted allele is located at the nuclear FS1 locus currently used by the USDA in conventional PCR tests to screen for evidence of Asian gypsy moth introductions or introgression. The diagnostic probe is successfully multiplexed with a conserved 18S probe system to detect reaction failure due to poor sample quality or quantity. The specificity, sensitivity, and repeatability of the FS1-18S multiplex real-time PCR assay were tested on laboratory-reared and field-collected moths to demonstrate diagnostic utility. Implications of the new assay as a screening tool for evidence of Asian gypsy moth introgression and introduction are discussed.
Cryptolaemus montrouzieri Mulsaut (Coleoptera: Coccinellidae) is an effective biological control agent of Australian origin, which has been introduced worldwide to control mealybugs. Although successfully used for >100 yr, its introduction in a new area may cause environmental risks should the populations become invasive. In the present study, a population genetics method was used to make predictions of the invasive potential of C. montrouzieri. Our results showed a similar level of genetic diversity among all populations. No significant genetic differentiation between native and introduced populations was observed, while three populations from the native region were significantly divergent. The fact that genetic diversity was not reduced in introduced areas suggests that no bottleneck effect has occurred during introduction. To avoid rapid evolution of the introduced C. montrouzieri, the introduction records of each population should be clearly traced and introductions from multiple sources into the same area should be avoided.
Biotypes of Russian wheat aphid, Diuraphis noxia (Kurdjumov), have nullified D. noxiaresistant wheat. In this study, feeding of North American D. noxia was measured in aphids fed resistant and susceptible wheat and barley using electrical penetration graph (EPG) recordings. Interactions between barley genotypes and D. noxia biotypes were significant. EPG recordings of biotype 1 aphids fed on D. noxia-resistant IBRWAGP4-7 barley plants displayed significantly more non-phloem (pathway) phase movements and significantly less sieve element phase (SEP) feeding than on susceptible plants. EPG recordings of D. noxia biotype 2 feeding are the first ever recorded, but no differences between biotype 2-susceptible and -resistant barley plants were found for any EPG parameter in biotype 2 aphids fed barley. No wheat genotype—D. noxia biotype interactions were detected, but when responses were averaged across resistant and susceptible wheat genotypes, biotype 1 displayed a significantly longer pathway phase and significantly more SEP feeding than biotype 2, and biotype 2 engaged in significantly more xylem drinking than biotype 1. IBRWAGP4-7 barley resistance to biotype 1 appears to be controlled by both intercellular factors encountered during the pathway phase and intracellular factors ingested during SEP feeding. The lack of differences in EPG parameters displayed by biotype 2 feeding on barley suggests that biotype 2 resistance in IBRWAGP4-7 barley is based on tolerance to D. noxia feeding instead of altered feeding patterns. Resistance in ‘KS94H871' wheat appears to be a function of phloem, nonphloem, and xylem factors that extend the duration of pathway feeding and limit SEP feeding.
The minimum temperature at which stored-product insects can move inside stored grain bulks with different grain moisture contents is not known. The movement of adults of four storedproduct insects, Cryptolestes ferrugineus (Stephens), Tribolium castaneum (Herbst), Sitophilus oryzae (L.), and Sitophilus zeamais (Motschulsky), at low temperatures inside jars or bulks of wheat with 11.1 or 16.0% moisture content was measured. Spontaneous walking stops (SMh), CCT (no movement after shaken), and minimum movement (TMmin, caught in probe pitfall traps) temperatures were determined at stepped-decrease of temperature. The ranges of SMh, CCT, and TMmin temperatures of the four stored-products beetles were 4.0 to 9.0°C, 2.0 to 8.0°C, and 6.0 to 11.5°C, respectively. The TMmin was ∼3°C higher than the SMh for all the tested beetles. C. ferrugineus had the lowest SMh, CCT, and TMmin temperatures, whereas S. zeamais had the highest values of these determined temperatures. C. ferrugineus under a faster stepped-decrease of temperature had higher SMh, CCT, and TMmin temperatures than that under a slower stepped-decrease of temperature, while adults of T. castaneum were not influenced by the temperature decrease rate. The two species of Sitophilus did not survive to the end of the experiment at the faster stepped-decrease of temperature. Two grain moisture contents did not affect these determined temperatures for all tested species.
Fumigated dry common beans (Phaseolus vulgaris L.) that were artificially infested with Acanthoscelides obtectus Say, and others that were not artificially infested, were stored in hermetic triple-layer PICS (Lela Agro, Kano, Nigeria) or woven polypropylene (PP) bags for 6mo at ambient laboratory temperature conditions of 22.6 ± 1.9°C and 60.1 ± 4.3% relative humidity. In an additional trial, beans contained in PP bags were treated with Actellic Super dust before introducing A. obtectus. Moisture content, number of live adult A. obtectus, seed damage, weight loss, and seed germination were determined at monthly intervals. At 6 mo, beans stored in PICS bags retained higher moisture than those stored in PP bags, but in all treatments the moisture level remained below that recommended for safe storage of beans. In the PICS bags, proliferation of A. obtectus did not proceed and at 6 mo, beans stored in these bags did not have insect-inflicted seed damage or weight loss. In contrast, seed damage and weight loss in PP bags exceeded economic threshold after 1mo in the absence of Actellic Super dust (Syngenta Crop protection AG, Basle, Switzerland), and after 2mo in the presence of it. Germination of beans stored in PP bags decreased greatly whereas the beans stored in PICS bags did not show reduced germination. Chemical free storage of common beans in PICS bags protects them against damage by A. obtectus.
Les haricots (Phaseolus vulgaris L.) fumigés puis artificiellement infestés avec Acanthoscelides obtectus Say, et non-infestes étaient stockés dans les sacs (PICS) à triple fonds ou dans les sacs nylons polypropylène (PP) pendant six mois dans les conditions ambiantes de laboratoire (température: 22.6 ± 1.9°C et humiditérelative: 60.1 ± 4.3%). Dans un autre essai, les haricots stockés dans les sacs nylons étaient traités avec la poudre d'Actellic Super avant d'introduire les insectes (A. obtectus). L'humidité des graines, le nombre d'insectes adultes vivants, les graines endommagées, la perte de poids, et la germination étaient mesurés mensuellement. Apres six mois de stockage, les haricots stockés dans les sacs PICS ont maintenu une humiditéélevée comparée à ceux stockés dans les sacs PP. Cependant, tous les traitements ont maintenu leur l'humiditédes grains en dessous du niveau recommandépour un bon stockage. Les sacs PICS ont arrêtéla prolifération de A. obtectus, les dommages des graines, et la perte de poids. En revanche, le dommage des graines et pertes en poids dans les sacs PP ont dépasséle seuil économique aprè s un mois sans traitement et deux mois avec traitement à l'Actellic Super. La germination des graines stockées dans les sacs PP a sensiblement diminuétandis que la germination des graines stockées dans les sacs PICS n'a pas étéréduite. Le stockage sans produit chimique des grains d'haricots dans les sacs PICS les protège contre les pertes post-récolte causées par A. obtectus.
Lasioderma serricorne (F.) is a serious pest of stored products that is known to be resistant to the fumigant pesticide gas phosphine. This study investigated resistance in populations from the southeastern United States, and determined if a recommended treatment schedule could kill resistant insects. A laboratory assay for adult insects was developed that used a discriminating concentration of 50 ppm phosphine applied to insects for 20 h at 25°C followed by 7 d of recovery in air. Survivors were classified as resistant. L. serricorne from six different field populations associated with stored tobacco were surveyed with the assay and all had resistant individuals. Four populations had greater than 90% of their insects resistant. Two industry-recommended treatment schedules were evaluated in laboratory fumigations against mixed life stage cultures of the four most resistant populations: the first at 200 ppm for 4 d at 25°C for controlling phosphine-susceptible L. serricorne and the second at 600 ppm for 6 d at 25°C intended to control phosphine-resistant beetles. The four populations with the highest frequency of resistant individuals from the field sampling study were not controlled by the “normal” treatment intended for susceptible insects. The higher concentration treatment greatly reduced beetle progeny from mixedstage colony jars, but there were substantial numbers of surviving adults from all four highly resistant populations that represented unacceptable levels of control.
This article is only available to subscribers. It is not available for individual sale.
Access to the requested content is limited to institutions that have
purchased or subscribe to this BioOne eBook Collection. You are receiving
this notice because your organization may not have this eBook access.*
*Shibboleth/Open Athens users-please
sign in
to access your institution's subscriptions.
Additional information about institution subscriptions can be foundhere