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

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, L. 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 an advantage over native species in its invasive range, potentially contributing to its invasion success.

Methods
In this Dataset, you can find data collected from three experiments in our research:

Widow spider behaviour with exposure to parasitoid wasps (three files)
Egg sac spike removal experiment (two files)
Egg sac morphology in response to exposure to wasps (one file)

The methods and analysis for each of the experiments are described in the manuscript Maternal care thwarts parasitoids in the invasive brown widow spider (Latrodectus geometricus).