Insect Herbivores on Parent Trees and Conspecific Seedlings in a Guyana Rain Forest

Abstract

More than 14,500 insect herbivores were collected in a rain forest in Guyana from 10,000 seedlings belonging to five plant species, their parent trees, and the forest understory. In October 1997, half (125) of the parent trees were felled to mimic selective logging. In this paper, we compare the insect fauna collected on the seedlings with that on the foliage of felled trees and discuss the findings with regard to the collections made in the understory. For a similarly sized sample, the foliage of felled trees yielded more than twice the number of insect species and 1.5 times as many individuals as did seedlings. More xylem-feeding Cicadellinae were collected from the seedlings, whereas more Acanaloniidae, Issidae, Flatidae, Tropiduchidae, and Lepidoptera were collected from the foliage of felled trees. Comparisons were complicated by the influx of understory species into the foliage of trees after felling. The dissimilarity of the data between seedlings and felled trees and the rather restricted occurrence of common insect species on the foliage of either seedlings or felled trees suggest, however, that few insect species forage both on seedlings and in the crowns of parent trees. Most species instead exploit the resources available either in the understory or in the canopy.