THE ECOLOGY OF THE NEW-WORLD FIG-PARASITIZING WASPS IDARNES AND IMPLICATIONS FOR THE EVOLUTION OF THE FIG-POLLINATOR MUTUALISM

Figs and their pollinating wasps are perhaps the classic example of an obligate mutualism. In addition, figs have a suite of non-pollinating parasitic wasps whose basic ecology is largely undescribed. Figs ther efore present the interesting situation of a hose that has two closely related taxa associated with it, one of which is mutualistic, the oth er parasitic. We show that the wasps belonging to the most abundant ge nus of New World parasites, the Idarnes wasps, develop at the expense of the pollinating wasps and not the viable seeds. However, the Idarne s wasps are not true parasitoids. We interpret these results to mean t hat the Idarnes wasps are in direct competition with the pollinator wa sps for the same pool of flowers in which the larvae of either group c an develop. Further, we infer that there is also a pool of flowers tha t cannot be exploited by either of these taxa. The observation that th e pollinators and the parasites oviposit from different sides of the f ruit strongly suggests that the basis for preserving some of the flowe rs to develop as viable seeds is not a direct result of spatial positi on of the ovaries or style length, as has been previously suggested. T his idea is corroborated by detailed observations in many other fig sy stems. Taken together, these findings suggest an explanation for the s tability of the fig-fig-pollinating wasp mutualism, as well as the str ucture of its parasite community.