Thermal ecology of Plesiopelma longisternale: novel insights and comparative analysis with a sympatric species

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  Thermal ecology of Plesiopelma longisternale: novel insights and comparative analysis with a sympatric species Abstract Understanding thermal responses in ectotherms is key to assessing vulnerability to climate change. Tarantulas (Theraphosidae) are informative models due to their sedentary lifestyle, long life cycles, and reliance on specific microhabitats. We present the first integrative assessment of the thermal ecology of Plesiopelma longisternale , a widespread Argentine species, combining experimentally derived thermal limits and thermal preferences with species distribution models, and compare its thermal profile with the sympatric Grammostola vachoni to explore patterns of thermal niche differentiation. Plesiopelma longisternale showed a minimum thermal limit near 4 °C, a maximum near 44 °C, a thermal optimum of 29.5 °C, a narrow thermal performance breadth, and a preferred temperature of approximately 32 °C. Models integrating climatic and thermal parameters predicted...

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