Interactions between pollinator and non-pollinator fig wasps: correlations between their numbers can be misleading

摘要

Ficus and their species-specific pollinator fig wasps represent an obligate plant-insect mutualism, but figs also support a community of non-pollinating fig wasps (NPFWs) that consist of phytophages and parasitoids or inquilines. We studied interactions between Kradibia tentacularis, the pollinator of a dioecious fig tree species Ficus montana, and an undescribed NPFWSycoscapter sp. Members of Sycoscapter sp. oviposited 2-4weeks after pollinator oviposition, when host larvae were present in the figs. No negative correlation was found between the numbers of the two wasp species emerging from figs in a semi-natural population. However, in experiments where the numbers of pollinator foundresses entering a fig were controlled, Sycoscapter sp. significantly reduced the numbers of pollinator offspring. Consequently, it can be concluded that Sycoscapter sp. is a parasitoid of K.tentacularis (which may also feed on plant tissue). Sycoscapter females concentrate their oviposition in figs that contain more potential hosts, rendering invalid conclusions based on simple correlations of host and natural enemy numbers.