Seed predation in Philodendron solimoesense (Araceae) by chalcid wasps (Hymenoptera).

International audienceThe relationships between Philodendron solimoesense and the larvae of two chalcid wasp species, inhabiting up to 88% of the infructescences, were studied in French Guiana. Exurus sp. (Chalcidoidea, Eulophidae, Tetrastichinae), is a gall maker and its larvae develop at the expense of seeds which are transformed into galls. We estimate that two seeds are necessary for the development of one eulophid. Their impact on plant reproductive success appears to be important, since parasitized fruits produce 60% fewer seeds than nonparasitized fruits and could explain the reduced seed set observed (53%). The larvae of a Sycophila sp. (Chalcidoidea, Eurytomidae, Eurytominae) are also present in the fruits of P. solimoesense occupied by eulophid larvae. The eurytomid larvae apparently develop at the expense of about one eulophid and are responsible for the death of 39% of them by direct predation or indirectly by consuming the gall tissues. Eulophids are far more abundant than eurytomids, since parasitized fruits contain an average of 11 eulophids but only one eurytomid. As chalcid wasp emergence takes place in a closed cavity and sex ratios are strongly biased in a given gall, local mate competition may occur as observed for fig wasps within figs