All size but lacks in venom - Male Steatoda nobilis show less diversity in latrotoxins : A comparative study including full body MALDI Imaging and differential venom proteomics.

The Noble false widow spider Steatoda nobilis (Sn) is a member of the Therididae family, akin the ¿true¿ Black widows of the genus Latrodectus. Sn is rapidly expanding its geographic range throughout Europe and parts of the Americas, particularly in and around human dwellings [Dugon, 2017]. This species has also been shown to be of medical significance in the UK and in Ireland, where a growing number of severe cases of envenomations has occurred over the past five years [Dunbar, 2021]. A recent study showed clear similarities between the venom composition of female Sn and the venom of Latrodectus [Dunbar 2020]. In particular, both venoms contain latrotoxins and latrodectins, which could explain the latrodectism-like symptomatology observed after envenomation by Sn. In this present study, we investigated the venom composition of male Sn and compared the results with the venom of females, using a proteo-transcriptomic approach. We also present the first whole-body imaging of a spider using MALDI mass spectrometry. This proof-of-concept allows to compare the anatomy of females and males based on molecular markers and could allow to identify regionalization on toxin production in venom glands when applied to other venomous animal groups.