Spider venom peptides Ht1a and Gg1a are toxic to honeybee parasite Varroa destructor by topical application

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  Spider venom peptides Ht1a and Gg1a are toxic to honeybee parasite Varroa destructor by topical application Abstract Global food supply strongly depends on honeybee pollination services, which are threatened by insecticides and pests such as parasitic Varroa destructor mites. Chemical varroacides/acaricides are hampered by resistance development, necessitating the development of sustainable and environmentally friendly alternatives, with arthropod venom peptides being considered promising sources of acaricidal toxins. With only a few acaricidal venom peptides being reported, we performed a systematic topical screening of 50 arthropod venoms against V. destructor , with 78% of the venoms causing 100% mortality after 24 h. Deconvolution of the venoms from the Tasmanian cave spider Hickmania troglodytes and the Giant Japanese funnel-web spider Gigathele gigas led to identification of the varroacidal peptides Ht1a and Gg1a. Topical application of Ht1a and Gg1a reduced varroa mite ...

Hunger-dependent female receptivity leads to variable optimal polyandry with equal fitness in a nuptial gift-giving spider

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Hunger-dependent female receptivity leads to variable optimal polyandry with equal fitness in a nuptial gift-giving spider

Abstract

Female mating decisions are often plastic, dependent on the environment. In the nuptial gift-giving spider Pisaura mirabilis, the optimal number of matings for females, i.e. the number that maximizes fitness, depends on prey availability and is regulated by hunger-dependent receptivity. We determined the lower and upper optimal number of matings for females (at high and low prey availability, respectively) and test the hypothesis that females that obtain the optimal number of matings will achieve that same reproductive success independently of what the optimal number is. In laboratory experiments, females were offered 0, 1, 2 or 3 house flies per day as supplementary feeding and were presented daily with 4 gift-carrying males until oviposition. Fecundity, oviposition latency, egg hatching success, and the number of live spiderlings were independent of the level of supplementary feeding. For females, mating and aggression towards males (gift stealing and sexual cannibalism) are alternative ways of compensating for low foraging success. We confirmed 2-3 as the minimum optimal number of matings. The maximum optimal number of matings varied between 12 and 22-24 depending on the females’ level of aggression. Female behavioral plasticity allows them to decouple their fitness from dependence on environmental prey availability through hunger-dependent receptivity.


Søren Toft, Maria J Albo, Hunger-dependent female receptivity leads to variable optimal polyandry with equal fitness in a nuptial gift-giving spider, Evolution, 2025;, qpaf087, https://doi.org/10.1093/evolut/qpaf087