Disentangling the coexistence strategies of mud-daubing wasp species through trophic analysis in oases of Baja California peninsula

Species within the same trophic level show different strategies to avoid
competition. Among these mechanisms, differences in body size,
spatio-temporal segregation, and diet preference often leads to a niche
partitioning. Nonetheless, little attention on coexisting predatory
insects and their network interactions has been paid. In this study, we
analyzed the strategies to avoid competition among three sympatric
mud-daubing wasps of the genus Trypoxylon (Hymenoptera: Crabronidae) in
oases and their surrounding xeric area from the Baja California peninsula,
Mexico. We compared the prey richness, composition and proportion of
spider guilds that were captured by the wasps. We tested whether the
differences in wasp body size explained the niche breadth, niche overlap
and the size of spider prey. We assessed the spider-wasp interactions
through a network analysis. With the use of trap-nests, we collected 52
spider species captured by the wasps. Both the guild and species
composition of preyed spiders was different between the three wasp
species. Differential proportions in the capture of spider guilds and a
little diet overlap were found among the wasp species. We found that the
wasp body size was positively correlated with prey size, but it was not a
proxy of niche breadth. Moreover, the largest wasp species was able to
nest in both mesic and xeric habitats, while the two smaller species were
restricted to the oases. This study reveals that the diversity of spiders
in oases of Baja California peninsula is crucial to maintain highly
specialized oasis-dependent wasp species. The niche partitioning between
mud-daubing wasps can be shaped by their inherent body size limitations
and hunting strategies through foraging specialization for specific spider
guilds. Food selection and slight differences in body size reduce
competition and allow the coexistence of sympatric wasps. Our study is the
first approach exploring the interaction networks between mud-daubing
wasps and their spider preys, highlighting new insights into the
morphological and ecological factors that shape antagonistic interactions,
and allow the coexistence of predators in deserts.