Abundance and Taxonomic Composition of Insects Emerging from Soil to Above-ground Ecosystems in Forests

Abstract

Insects that live in soil until pupal stage and then emerge into above-ground may constitute a significant portion of the energy flow from soil to above-ground ecosystems. As the first step for this research, we captured flying insects by emergence traps established at two forests in two seasons, and classified them into several functional groups by their food habits and life histories. The mean number of insects captured was 20.5/m²/day in early-summer and 16.2/m²/day in autumn, and the most abundant taxon was Nematocera (mean number: 18.2/m²/day in early-summer, 12.6/ m²/day in autumn). Nematocera could be divided into two groups based on their soil utilization patterns and food habits. One group inhabits in soil during egg-pupal stage, and is considered to be detritivores or fungivores, e.g. Sciaridae and Chironomidae. Another group lives in soil only around pupal stage, which inhabits above-ground as herbivores or predators in larval stage, e.g. some super-tribes and tribes of Cecidomyiidae. The abundance of detritivores and fungivores was larger at pine forest than at deciduous forest, although the reason is still unknown.