Abstract: Through controlling the number of ovipositing foundresses inside a fig, and combining with the observation of ovipositing behavior and mating behavior, this paper studied the sex ratio of Apocryptophagussp., a species of nonpollinating fig wasps hosted on Ficus semicordata in Xishuangbanna. The results showed that female Apocryptophagussp. started to visit the fig on the 3rd day after pollinator Ceratosolen gravelyi oviposited. Apocryptaphagus sp. oviposited on the outside of the fig, and the ovipositing lasted for 2 days. Male Apocryptophagus sp. emerged at the same time with pollinators. The males opened a small hole on the wall of gall where the females developed, and mated with the females. Mated females emerged from their development fig, and left for a new receptive fig. The sex ratio of Apocryptaphagus sp. was in agreement with local mate competition theory, i.e., it was female-biased. Meanwhile, the total number of offspring increased with increasing foundress number. In contrast, the average number of offspring per foundress decreased. At individual level, when a female laid eggs inside a fig, the sex ratio of offspring correlated negatively with the number of offspring.

Key words: fine root functional trait, diameter class, Zenia insignis plantation, rhizosphere soil