Abstract: Most males of fig wasps are restricted to the cavity of fig fruits for the whole life. There are remarkable differences in fig fruit cavities. These differences can constrain the movement of males. It has been shown that the size of cavities of different fig fruits could influence male fighting behavior. We ask whether the size of cavities of fig fruits can constrain the leg morphology and scramble behavior of the male wasps. Thus we collected fig fruits from five fig species in the field during June, 2008 to October, 2009. We investigated leg morphology and scrambling behavior of Philotrypesis spp. inhabited in those fig fruits. Two morphological types were identified according to hindleg tarsi among the males collected from different fig species: type Ⅰ: the basal two hindleg tarsi are close to each other and hindleg middle tarsi are not robustious; type Ⅱ: the basal two hindleg tarsi are separated widely and hindleg middle tarsi are robustious. The results of GLM indicated the differences were remarkable in the ratio of length and width of foreleg femur of the males collected from different fig species (F_{8, 81}=94.86, P<0.001). Males in big fig fruits had slighter foreleg femur and males in small fig fruits, except that M7#c-ben had robustious one. Males scrambled for mating in the fig fruit through robustious forelegs or flexible hindlegs. The results suggest that the size of fig fruit cavity can constrain the movement of Philotrypesis males and influence morphological adaptation of their legs.

Key words: Fig wasp, non-pollinating wasp, Philotrypesis, behavior, morphological adaptation, fig fruit cavity