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Diaphaniaglauculalis (Guenée) is a defoliating pest of the Laran tree, Anthocephalus chinensis (Lamk.) Rich. ex Walp., which is an important tree species for reforestation efforts in tropical and subtropical regions. Currently, little information is available about the calling behavior and pheromone production of D. glauculalis females, but such information is important in developing pheromone-based monitoring systems for the pest. Thus, female calling behavior and its correlation with pheromone production was studied using electroantennogram (EAG) technology, qualitative analysis of gas chromatography-mass spectrometry (GC-MS), and Y-tube olfactometer assays. Calling females release a sex pheromone from a gland located on the dorsal membrane between the eighth and ninth abdominal segments, as observed with a stereomicroscope. Peak calling behavior occurred with females 3 d after emergence and 6 h into the scotophase. Pheromone release typically increased with the female age and scotophase and then decreased gradually. GC-MS analysis showed that the amount of pheromone in extracts from the pheromone glands were greatest at the onset of the calling behavior and decreased thereafter. Y-tube olfactometer assays confirmed that pheromone gland extracts at 6 h into the scotophase elicited stronger attractiveness in comparison to 5, 7, and 8 h after emergence.
The tomatillo, Physalis ixocarpa Brotero, is an important vegetable in central Mexico but production is limited by the psyllid pest Bactericera cockerelli (Sulc) (Hemiptera: Trizoidae). This study was undertaken in 2016 to generate maps of the spatial distribution of B. cockerelli in the municipalities of Luvianos, Jocotitlán, and Ixtlahuaca in the State of Mexico to support implementation of integrated pest management strategies to improve tomatillo production. Geostatistical analysis was performed to estimate the experimental semivariogram and fitted to a theoretical model with the program Variowin 2.2. All generated models were validated. It was determined that for the three municipalities evaluated, 29 semivariograms were the adjusted spherical model, four were the Gaussian model, and three were the exponential model. Aggregation maps of the pest were evaluated in all plots, and areas were identified with the highest incidence of the pest, thus allowing initiation of control measures at selected sites while decreasing environmental impact and improving cost effectiveness.
Several insect species are mass produced for animal feeds, fish bait, or human consumption. The yellow mealworm, Tenebrio molitor L. (Coleoptera: Tenebrionidae), is one of the more-popular insects considered for this use. To make T. molitor competitive with more-traditional protein sources, mass production must be optimized. Herein, we review the scientific literature on the range and optimal environmental, physical, and dietary conditions for the rearing T. molitor. Our review identified that: (a) the optimum temperature for T. molitor growth is 25–28°C; (b) T. molitor larval growth rate is greatest at ≥70% relative humidity (RH) with an optimum range between 60–75% RH, and; (c) optimal growth is achieved with diets containing 5–10% yeast, 80–85% carbohydrate, and the addition of B-complexvitamins.
Conogethespunctiferalis Guenee is a polyphagous insect pest that is difficult to manage because it feeds within plant tissue. Management by mass trapping using semiochemicals, especially pheromones, represents a viable option to control such borers. Herein, pheromonal compounds were extracted from male and female moths and assessed using headspace sampling and electroantennogram response. One-d-old C. punctiferalis showed a higher response to volatile solvents than 4-d-old ones, irrespective of sex. The male antenna was found more sensitive than the female for volatile compounds. However, the female response to male headspace extract and abdominal tip extract was very high (i.e., 4.006 mV and 2.217 mV, respectively), which revealed the presence of males producing a female-attracting olfactory cue in C. punctiferalis. This was also confirmed by males calling the female before mating by extruding the hair pencils in their abdominal tip. The male pheromone extract when analyzed in gas chromatography–mass spectrometry indicated the presence of methyl acetophenone or 3-ethyl acetophenone.
Glossina spp. (Diptera: Glossinidae) vector trypanosomes, the causal pathogens of trypanosomiasis in humans and animals. Glossina spp. chemosensory mechanism is relevant to understanding the behavioral responses of these insects to environmental cues. Odorant binding proteins (OBPs) are involved in either olfactory or nonolfactory cue sensation depending on their spatial and temporal expression. In most insects, the OBPs are ubiquitously expressed, although the levels are higher in the antennae. This study was aimed at determining the differential gene expression patterns of OBP genes in the developmental stages (larval, pupal, teneral) and differentially starved adults of Glossina brevipalpis (Newstead) collected from Shimba Hills National Park, Kenya. Five OBP genes, GbrOBP2, GbrOBP6, GbrOBP7, GbrOBP8, and GbrOBP13, were selected for quantitative PCR expression analysis as representatives of the three OBP classes in Glossina spp. (classic, minus-C, classic-dimers). Antennal samples from the newly emerged insects (tenerals) served as the controls. GbrOBP2 was highly expressed in both larval and pupal stages, whereas GbrOBP7 was expressed in the pupal stage. GbrOBP8, GbrOBP13, and GbrOBP6 showed high expression in adult antennas. Expression of OBPs in the immature stages suggested OBP involvement in nonolfactory chemical sensation, whereas that in adult antennae was attributed to olfaction.
Ten sorghum, Sorghum bicolor (L.) Moench, lines near or in commercial release were evaluated with the intent of identifying the phenotypic expression of host-plant resistance to the sugarcane aphid Melanaphis sacchari (Zehnter) (Hemiptera: Aphididae). Two of the 10 entries (OL2042 and SP7715) expressed a high degree of resistance to the sugarcane aphid, with damage ratings <3.0 (damage rating scale of 1.0 to 9.0, with 1.0 being no damage and 9.0 a dead plant) and were not significantly different than the known resistant Tx2783. Screening the four other entries (OL0029, SP74C40, SP78M30, and SP73B12) resulted in having very good expression of resistance scoring between <3.0 and >4.0 and were statistically lower than the susceptible check Tx7000. Chlorophyll loss and damage ratings exhibited a linear relationship (R2 = 0.87), followed by a slight improvement (R2 = 0.89) in the regression models when the difference in plant height was added as a second independent variable. The relationship helps explain the degree of tolerance when sorghum is challenged with high sugarcane aphid densities. These results provide sorghum producers with options for planting sorghums resistant to sugarcane aphid while allowing for more time to find and develop new sources of resistance.
In 2010, the Mexican government implemented a program of augmentative releases of Tamarixia radiata (Waterston) to combat the Asian citrus psyllid Diaphorina citri Kuwayama. By March 2016, 40.4 million parasitoids had been released in areas where D. citri was not managed (e.g., abandoned orchards, urban areas) in 19 Mexican states. The impact of such releases was assessed by quantifying the parasitism of D. citri nymphs by T. radiata in urban areas of western Mexico during 2013–2015. These surveys determined that a mean (± SD) of only 10.95 ± 2.01% were parasitized naturally, whereas 60.58 ± 1.66% were parasitized in areas following augmentative releases. The performance of the releases was higher in warm, subtropical areas, such as the states of Colima (73.11 ± 3.69%) and Nayarit (71.44 ± 2.61%), compared with Jalisco (37.19 ± 2.13%) in cooler and less tropical conditions. These results indicate the Mexican program releases of T. radiata in areas not managed for the Asian citrus psyllid can add to the tactics for control of this pest and the bacterium it vectors.
In recent years, plant derivatives such as essential oils have been one of the most promising sources for the substitution of chemical insecticides for pest management. A laboratory assessment was conducted to find the fumigant toxicity of Artemisia sieberi Besser, Pelargonium roseum Andrews, and Ferula gummosa Boiss essential oils against the sweetpotato whitefly Bemisia tabaci Gennadius and its predator, Orius albidipennis Reuter. The responses varied depending on oil type and insect species. Based on 24-h median lethal concentration (LC50) values, all the essential oils showed similar toxicity to B. tabaci. Ferula gummosa essential oil had lesser toxicity (LC50, 3.46 μll−1 air) than P. roseum (LC50, 0.95 μll−1 air) and A. sieberi (LC50, 0.62 μll−1 air) against O. albidipennis. The toxicity of the oils increased for both insects by increasing the exposure time from 3 h to 48 h. A comparison of the essential oils' toxicity on the two insects showed a lower susceptibility of O. albidipennis to the tested essential oils, which is a promising result for the control of B. tabaci in integrated pest management programs.
Rhaetuswestwoodi Parry (Coleoptera: Lucanidae) is the type species of monotypic genus Rhaetus Parry, which is distributed only in the region of the Eastern Himalayas. Little is known about the biology, ecology, genetics, and conservation status of this rare beetle. In this study, the mitochondrial genome of R. westwoodi was sequenced for the first time to obtain useful genetic data for this monotypic genus. Like most of known mitogenome in beetles, the mitochondrial genome of R. westwoodi is a closed circular molecule 18,134 bp in length, comprising 13 protein-coding genes, 22 transfer RNA (tRNAs) genes, 2 ribosomal RNAs (rRNAs), and 1 control region. The nucleotide composition is 36.30% adenine (A), 31.20% thymine (T), 21.49% cytosine (C), and 11.01% glycine (G), with a highly biased AT content of 67.50%. The phylogenetic analysis showed that R. westwoodi and Hexarthrius vitalis Tsukamotoi were recovered as one clade with strong nodal support (1.00 Bayesian Phylogenetics and Phylogeography [BPP], 100% maximum likelihood bootstrap [MLB]). The topology also strongly supported that R. westwoodi appeared to be a sister species to Pseudorhaetus sinicus Boileau (1.00 BPP, 100% MLB).
The lethal effects of three synthetic (deltamethrin thiacloprid, lambda-cyhalothrin, deltamethrin) and two botanical (Palizin®, Sirinol®) insecticides were assayed in laboratory conditions against adult and immature stages of Trissolcus grandis (Thomson), an egg parasitoid of Eurygaster integriceps Puton (Hemiptera: Scutelleridae). Contact bioassays determined that the synthetic insecticides caused 100% mortality of the adult wasps, while the two botanical insecticides had no lethal effects on the adults. The highest level of emergence of T. grandis females from E. integriceps eggs treated with the synthetic insecticides was observed after treatment with lambda-cyhalothrin, and the lowest adult emergence occurred following treatment of the eggs with deltamethrin thiacloprid. Exposure of E. integriceps eggs with Sirinol impacted parasitoid emergence, but the lowest mean percentage of emergence of adults was from eggs treated when the parasitoids were second instars or pupae. Treatment of eggs with Palizin had no impact on the emergence of adults or on the activity of the parasitoid after emergence. Of these materials assayed, Palizin appears to be an excellent candidate for use in integrated pest management programs for E. integriceps.
Life history evolution involves a series of trade-offs to maximize reproductive success at the expense of other physiological systems. Within insects, increased body size is associated with increased fecundity in males and females alike; hence, increased body size should be favored even if it is detrimental in the short term. The righting response is a reflexive mechanism used by individuals to regain proper dorsoventral orientation and is conserved among terrestrial animals of multiple taxa to avoid the consequences of being helpless on one's back. In this study, we examined the righting response as it related to body size in the cinereous cockroach, Nauphoeta cinerea (Olivier), of both sexes and found that larger individuals were slower to right themselves relative to smaller individuals. Moreover, the reproductive history of the individual at testing differentially affected this relationship in a sex-specific manner. Individual females that were presumed mated at the time of testing were slower to right themselves than were same-sized males, while virgin females righted themselves more quickly. Taken together, these findings suggest that the reproductive gains associated with an increased body size within this species come at the expense of righting ability and that this outcome is compounded by reproductive history.
Monochamusalternatus Hope, the Japanese pine sawyer (Coleoptera: Cerambycidae), is a longhorn beetle that is a known vector of the pinewood nematode Bursaphelenchus xylophilus (Steiner et Buhrer) Nickel. Beauveria bassiana (Balsamo) Vuillemin is an entomopathogenic fungus that is widely used as a microbial control agent because of its ease of mass production and safety to most vertebrates. To identify molecular targets that are potentially associated with B. bassiana toxicology, differentially expressed gene (DEG) libraries of M. alternatus contacted with B. bassiana have been prepared. The transcripts are sequenced using the Ion Proton platform; We identify 5,637, 9,181, and 1,787 sequences that involved cellular components, molecular functions, and biological processes, respectively. Fifty DEGs are enriched in the metabolism of xenobiotics by the cytochrome P450 pathway, and 33 DEGs are enriched in insect hormone biosynthesis by a Kyoto Encyclopedia of Genes and Genomes pathway enrichment analysis of the DEGs. The pathways associated with these unique candidate targets yield new insights that will lead to an improved understanding of their functions and relationships. Artificial utilization of B. bassiana may be beneficial to the biological control of M. alternatus and other pests.
The sublethal effects of buprofezin, abamectin, and a plant-derived extract from aerial portions of Echinophora platyloba DC (Umbelliferae) on the mortality, developmental time, adult longevity, and fecundity of the parasitoid Encarsia formosa Gahan were studied. Laboratory bioassays determined that the median lethal concentrations (LC50) of abamectin, buprofezin, and the Echinophora platyloba extract were 724.2, 1,202.9, and 894.4 mg/l for larvae, 971.4, 1,380.2, and 1,287.0 mg/l for pupae, and 306.2, 3,309.1, and 831.7 mg/l for adults, respectively. Preadult development time was reduced following exposure to sublethal concentrations (LC30) of all insecticides (P < 0.01). Treatment of larvae and pupae with buprofezin or abamectin significantly decreased adult longevity (P < 0.01); however, the E. platyloba extract reduced adult longevity only when exposed during the pupal stage. Adult fecundity was not affected when larvae or pupae were treated with any of the insecticides (P > 0.05). However, decreased fecundity was observed when adult wasps were exposed to abamectin and, to a lesser extent, the E. platyloba extract (P < 0.01). In comparison to abamectin, sublethal concentrations of the E. platyloba extract and buprofezin are less harmful to the survival, longevity, and fecundity of Encarsia formosa and should be further developed for use in integrated pest management of the greenhouse whitefly, Trialeurodes vaporariorum Westwood, in greenhouse production systems.
The oil palm, Elaeis guineensis Jacquin, is an allogamous and monoecious plant that is mainly pollinated by insects such as Mystrops costaricensis Gillogly (Coleoptera: Nitidulidae) and Elaeidobius kamerunicus Faust (Coleoptera: Curculionidae). To determine the relationship between inflorescences and pollinators as well as the relationship between pollinators and bunch components, 858 palms, divided equally between two plots planting with cultivars tenera and dura of E. guineensis, were monitored every 2 weeks over 1 yr. Male inflorescences (MIs) and female inflorescences (FIs) at anthesis, and pollinators collected from the inflorescences, were recorded at each sampling. Bunch components and the amount of rainfall during the study period also were recorded. Data were analyzed using Spearman correlations and linear regression. Significant positive correlations of the total number of MIs with the total number of pollinators were found in both cultivars (ρ = 0.72, P < 0.0001, n = 24 in cultivar tenera; ρ = 0.65, P = 0.0003, n = 26 in cultivar dura). The number of pollinators were linearly related with number of MIs in both cultivars (F = 0.002; r2 = 0.50 in cultivar tenera; F = 0.0005; r2 = 0.40 in cultivar dura). For both cultivars, we found significant negative correlations of the MIs and FIs with the rainfall recorded between 21 and 24 mo before anthesis. The number of MIs and the amount of rainfall were directly related to the number of pollinators. There was an inverse relationship of the inflorescences with the rainfall recorded between 21 and 24 mo before anthesis.
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