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
The association of unrelated ant queens(pleometrosis)is supposed to improve nest foundation and competitiveness under environmental stress,but its evolutionary maintenance is difficult to explain because only one of t...The association of unrelated ant queens(pleometrosis)is supposed to improve nest foundation and competitiveness under environmental stress,but its evolutionary maintenance is difficult to explain because only one of the queens survives after nest foundation.My aim was to test the potential effect of queen association as a social buffer,that is,as a mechanism reducing stress and improving fitness due to the benefits of social contact.I analyzed the survival,fecundity,and behavior of isolated and paired Lasius flavus queens exposed and not exposed to stressors(disturbing environmental conditions).I found no difference in survivorship between isolated and paired queens or between stressed and unstressed isolated queens.Groups in which 1 or 2 paired queens were stressed showed higher mortality.Unstressed queens died similarly to their stressed nestmates,suggesting stress transmission.A trend suggested that paired queens produced eggs more quickly,but eggs were produced similarly between isolated and paired queens.Social avoidance was observed in groups with 1 stressed and 1 unstressed queen.However,the groups with 2 stressed queens showed the expected behaviors according to social buffering:lower mobility and more interindividual inspection.My findings suggest the synergistic effect of pleometrosis and stress and the dependence of stress level similarity between nestmates on social buffering or rejection on ant queens.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.
基金funded by a postdoctoral fellowship of the Galician government(Xunta de Galicia“Axudas de apoio a etapa posdoutoral 2017”,ref:ED481B-2017/034).
文摘The association of unrelated ant queens(pleometrosis)is supposed to improve nest foundation and competitiveness under environmental stress,but its evolutionary maintenance is difficult to explain because only one of the queens survives after nest foundation.My aim was to test the potential effect of queen association as a social buffer,that is,as a mechanism reducing stress and improving fitness due to the benefits of social contact.I analyzed the survival,fecundity,and behavior of isolated and paired Lasius flavus queens exposed and not exposed to stressors(disturbing environmental conditions).I found no difference in survivorship between isolated and paired queens or between stressed and unstressed isolated queens.Groups in which 1 or 2 paired queens were stressed showed higher mortality.Unstressed queens died similarly to their stressed nestmates,suggesting stress transmission.A trend suggested that paired queens produced eggs more quickly,but eggs were produced similarly between isolated and paired queens.Social avoidance was observed in groups with 1 stressed and 1 unstressed queen.However,the groups with 2 stressed queens showed the expected behaviors according to social buffering:lower mobility and more interindividual inspection.My findings suggest the synergistic effect of pleometrosis and stress and the dependence of stress level similarity between nestmates on social buffering or rejection on ant queens.