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 ...

Maternal care thwarts parasitoids in the invasive brown widow spider (Latrodectus geometricus)

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Maternal care thwarts parasitoids in the invasive brown widow spider (Latrodectus geometricus)

Abstract

Maternal care can maximize offspring survival and may contribute to the establishment success of invasive species. The brown widow spider, Latrodectus geometricus, is a successful invader worldwide. Here, we investigated the role of maternal care in enhancing its success. We compared the defence mechanisms of the invasive L. geometricus with those of another widow spider native to the Negev desert, Latrodectus pallidus, against an egg sac parasitoid wasp. Both spider species exhibited guarding behaviours following exposure to wasps; however, only L. geometricus efficiently evaded and successfully killed the parasitoid. Accordingly, its egg sacs were parasitized less frequently than those of L. pallidus. Next, we evaluated the defensive role of the silk spike-like structures on L. geometricus egg sacs. When spikes were removed from half of the egg sac surface, the wasps laid more eggs on the spike-free side. In an additional experiment, L. geometricus females increased spike density on subsequent egg sacs after exposure to the parasitoid. We showed that L. geometricus employs both behavioural defences and modifications to the egg sac structure to protect against the parasitoid. These defences may provide L. geometricus with an advantage over native species in its invasive range, potentially contributing to its invasion success.

Arabesky Valeria, Johnson Alfred Daniel, Rozenberg Tamir, Lubin Yael, Segoli Michal and Mowery Monica A. 2025 Maternal care thwarts parasitoids in the invasive brown widow spider (Latrodectus geometricus)Proc. R. Soc. B.29220242735 http://doi.org/10.1098/rspb.2024.2735