Cotton leaf worm, Spodoptera littoralis, is considered one of the most common arthropod pests that contribute to crop devastation of cotton. Previously, agricultural pests were controlled through the application of ch...Cotton leaf worm, Spodoptera littoralis, is considered one of the most common arthropod pests that contribute to crop devastation of cotton. Previously, agricultural pests were controlled through the application of chemical insecticides. However, insecticide-resistant insect populations emergence, as well as increasing concerns about the environmental and human health risks. Venomous animals introduce valuable sources of bioactive compounds which are employed for defence. Some of these toxins have high phyletic specificity, making them appropriate for use in IPM programs. This study aims to test the insecticidal effects of Polistes dominulus and Apis mellifera venoms. Crude venoms were examined for their insecticidal effect against cotton leaf worms by four different application methods including: leaf dipping, integument dropping, spraying, and injection. The data demonstrated a strong response to purified (Polistes dominulus) venom at an initial time than that of honey bee (Apis mellifera) which increases response with increasing the dose and the time interval. A dosage of 0.015 - 0.16 ml of both venoms had notably varied in LD<sub>50</sub> values on Spodoptera littoralis that showed higher wasp venom toxicity. Cotton leaf worms showed more susceptibility and mortality to the Polistes sp. venom than that of honey bees.展开更多
Eusocial wasps are excellent models for understanding polyethism and division of labor among castes in social insects. However, little is known about the mechanisms controlling caste determination in eusocial wasps. E...Eusocial wasps are excellent models for understanding polyethism and division of labor among castes in social insects. However, little is known about the mechanisms controlling caste determination in eusocial wasps. Evidence suggests that the phenotype of queens in independent-founding (IF) eusocial wasps of the subfamily Polistinae can be partly fixed in the larval stage;however, this hypothesis has not yet been investigated. In this study we evaluate whether juvenile hormone (JH) affects pre-imaginal caste determination in the IF eusocial wasp Mischocyttarus consimilis (Hymenoptera: Vespidae). Analyzing morphometric and behavioral data, we demonstrated experimentally that females emerging from larvae that were treated with JH in the third instar had a significantly larger body size, spent more time in the nest, and were subject to less physical aggression from nestmates compared with females emerging from untreated control larvae. These results indicate that phenotype differences among castes in IF eusocial wasps can be partly fixed in the pre-adult stage and influenced by variations in the JH titer.展开更多
Increasing evidences indicate that male haploid are more susceptible to parasites than female diploid(workers,alate females and queens)although the generality and reasons causing such susceptibility are still under de...Increasing evidences indicate that male haploid are more susceptible to parasites than female diploid(workers,alate females and queens)although the generality and reasons causing such susceptibility are still under debate.The male haploids in eusocial Hymenoptera are perfect for examining the susceptibility assumption and unveiling the molecular mechanisms of this assumption.In the present study,the males,workers and alate females of red imported fire ants(Solenopsis invicta)were challenged with entomopathogenic fungus Metarrhizium anisopliae.By measuring the LC50 values of M.anisopliae against different castes of S.invicta,we found that haploid males suffered from reduced disease resistance than diploid workers and alate females,a proof that haploid susceptibility was diminished in S.invicta.In this study we also examined the assumption that males invest less in innate immunity contributing to haploid susceptibility based on the transcript levels of genes encoding antimicrobial peptides(AMP)with quantitative reverse transcription-PCR(qRT-PCR).We found that infection increased the mRNA levels of hymenoptaecin in females(workers and alate females),but not in males;no significant difference was found in the mRNA levels of defensin,transferrin or crustin between infected ants and control ants in each sxe/castes.However,this study suggested that any resistance traits like behavioral and other immunological responses,are contributing to haploid susceptibility.展开更多
文摘Cotton leaf worm, Spodoptera littoralis, is considered one of the most common arthropod pests that contribute to crop devastation of cotton. Previously, agricultural pests were controlled through the application of chemical insecticides. However, insecticide-resistant insect populations emergence, as well as increasing concerns about the environmental and human health risks. Venomous animals introduce valuable sources of bioactive compounds which are employed for defence. Some of these toxins have high phyletic specificity, making them appropriate for use in IPM programs. This study aims to test the insecticidal effects of Polistes dominulus and Apis mellifera venoms. Crude venoms were examined for their insecticidal effect against cotton leaf worms by four different application methods including: leaf dipping, integument dropping, spraying, and injection. The data demonstrated a strong response to purified (Polistes dominulus) venom at an initial time than that of honey bee (Apis mellifera) which increases response with increasing the dose and the time interval. A dosage of 0.015 - 0.16 ml of both venoms had notably varied in LD<sub>50</sub> values on Spodoptera littoralis that showed higher wasp venom toxicity. Cotton leaf worms showed more susceptibility and mortality to the Polistes sp. venom than that of honey bees.
文摘Eusocial wasps are excellent models for understanding polyethism and division of labor among castes in social insects. However, little is known about the mechanisms controlling caste determination in eusocial wasps. Evidence suggests that the phenotype of queens in independent-founding (IF) eusocial wasps of the subfamily Polistinae can be partly fixed in the larval stage;however, this hypothesis has not yet been investigated. In this study we evaluate whether juvenile hormone (JH) affects pre-imaginal caste determination in the IF eusocial wasp Mischocyttarus consimilis (Hymenoptera: Vespidae). Analyzing morphometric and behavioral data, we demonstrated experimentally that females emerging from larvae that were treated with JH in the third instar had a significantly larger body size, spent more time in the nest, and were subject to less physical aggression from nestmates compared with females emerging from untreated control larvae. These results indicate that phenotype differences among castes in IF eusocial wasps can be partly fixed in the pre-adult stage and influenced by variations in the JH titer.
文摘Increasing evidences indicate that male haploid are more susceptible to parasites than female diploid(workers,alate females and queens)although the generality and reasons causing such susceptibility are still under debate.The male haploids in eusocial Hymenoptera are perfect for examining the susceptibility assumption and unveiling the molecular mechanisms of this assumption.In the present study,the males,workers and alate females of red imported fire ants(Solenopsis invicta)were challenged with entomopathogenic fungus Metarrhizium anisopliae.By measuring the LC50 values of M.anisopliae against different castes of S.invicta,we found that haploid males suffered from reduced disease resistance than diploid workers and alate females,a proof that haploid susceptibility was diminished in S.invicta.In this study we also examined the assumption that males invest less in innate immunity contributing to haploid susceptibility based on the transcript levels of genes encoding antimicrobial peptides(AMP)with quantitative reverse transcription-PCR(qRT-PCR).We found that infection increased the mRNA levels of hymenoptaecin in females(workers and alate females),but not in males;no significant difference was found in the mRNA levels of defensin,transferrin or crustin between infected ants and control ants in each sxe/castes.However,this study suggested that any resistance traits like behavioral and other immunological responses,are contributing to haploid susceptibility.
