Insect galls of Costa Rica and their parasitoids

Abstract

Approximately 1,100 morphospecies of gall-inducing insects have been found thus far in Costa Rica. Seventy percent of these are Cecidomyiidae, a group whose true species richness is potentially huge; other prominent groups include Psylloidea, Hymenoptera (5 families), and Lepidoptera (14 families). About half of the lepidopteran galls are induced by Momphidae on Melastomataceae and these galls are more modified than most other lepidopteran galls. Some groups of gall-inducers are probably much more diverse than present numbers suggest because their galls are hidden, for example eulophid galls in fruits of Araceae and braconid galls in fruits of Fabaceae, Melastomataceae, and Rubiaceae. Eleven families of hymenopteran parasitoids have been reared from galls in Costa Rica. Platygastridae are restricted to cecidomyiid galls and Encyrtidae occur in either sternorrhynchan (Hemiptera) or lepidopteran galls, whereas Eupelmidae and Torymus (Torymidae) are associated with a diversity of gall-inducers. An independent inventory of Entedonini (Eulophidae) and the resulting taxonomic monographs allow for a more detailed analysis of this group, which shows that while the vast majority of Chrysonotomyia and Omphale species are probably associated with galls, very few have been reared: only 27 of 97 species, and 10 of 129 species, respectively. This and other evidence suggest that many, perhaps most, insect galls remain to be discovered.