Specificity of Seed-Attacking Beetles in a Costa Rican Deciduous Forest

Abstract

SUMMARY (1) The deciduous forests and the riparian evergreen vegetation that they include in the lowlands of Guanacaste Province, Costa Rica, contain at least 975 species of dicotyledonous plants. At least 110 species of beetles (Coleoptera) whose larvae are seed-predators were reared from more than 3700 samples of fruits and seeds of these plants. (2) At least 100 species of these plants usually had beetle seed-predators (Bruchidae, Curculionidae, Cerambycidae) in their mature or nearly mature fruits or seeds. (3) Most (75%4) of the species of beetles were specific to a particular plant species; 14 preyed on two plant species, 9 on three, and 2 on four. The bruchid Stator pruininus preyed on six species and S. limbatus on eight species. (4) Of the 100 species of plants whose seeds were preyed on regularly by beetles, 63 were in the Leguminosae, 11 in the Convolvulaceae, and the remainder were spread among sixteen other plant families. (5) Of these 100 prey species, 59 were fed on by a single species of beetle, 25 by two species of beetles, 11 by three, 4 by four and one, Cassia leptocarpa, by five species of beetles. (6) In at least 90%Y of seed or fruit samples, all species of beetles attacking that species in the study area were present. Of the 100 species of beetles, eighty were found in the first sample of the appropriate fruit or seeds. The prey of ten additional species of Bruchidae in the study area is unknown, but will be other than the prey species listed here. (7) With some striking exceptions, the prey species of those beetle species which preyed on more than one plant species were closely related. In contrast, in those cases where there were two or more congeneric plant species in the study area, the species of beetle which attacked one or more of them left unattacked an average of 5.8 of the congeneric plant species.