Nematode infection of male fig wasps: Potential benefits for nematodes and consequences for fig-fig wasp communities

The community comprised of figs, fig wasps, and wasp-vectored entomopathogenic nematodes forms an excellent interaction network to examine the role of individual interactions on community co-evolution and coexistence. Pollinating fig wasp females are definitive hosts for nematodes because they provide transportation to and nutrition within their reproductive environment (a new fig). Conversely, fig wasp males (adults emerge 3-5 days earlier than females) never leave a natal fig and therefore cannot provide nematodes access to a new fig. Thus, nematode infection of male wasps should be strongly selected against as a reproductive dead-end. Previous observations indicated that such infective events do occur, but the frequency and ecological relevance of this interaction remained uncertain. In a survey of the Ficus petiolaris community in Baja California, Mexico, we found that nematode infection of male fig wasps is surprisingly common, present in 48% of sampled nematode-infested figs. Nematodes were observed consuming their male hosts and forming enormous mating aggregates on their bodies. This consumption appeared facilitated by a mouth-part polyphenism that differed substantially from nematodes emerging from female wasps. Overlap of nematode generations was also observed, suggesting the development of a second nematode generation within the fig in-sync with definitive female wasp host dispersal. This suggests that rates of evolution between nematodes and their wasp hosts may be more dissimilar than previously assumed. Interestingly, infections of non-pollinating fig wasp males were especially common, and may result in fewer non-pollinating females exiting the natal fig inseminated, suggesting a novel role for infection on community modulation.