Distribution pattern and competition of insects breeding on Camellia japonica flower

Abstract

The distribution pattern and competition of insects exploiting Camellia japonica flowers were studied in Tokyo, central Japan, to understand how their distributions are determined. Dasiops sp. of Lonchaeidae (Diptera) exploited flower buds and showed random distribution, whereas Drosophila unipectinata, D. oshimai and D. lutescens of Drosophilidae (Diptera) and Epuraea commutata of Nitidulidae (Coleoptera) exploited fully opened, late and fallen flowers and showed aggregated distribution. From the distribution pattern, it is assumed that Dasiops sp. has clutches of single egg whereas drosophilid and nitidulid species have clutches of more than one egg. In resource supplementary experiments, body size of drosophilid flies increased if resources were supplemented, although their survival is assumed to be unaffected. However, their body size did not decrease with increase of larval density in resource patches. It is therefore unclear whether resource competition occurs among drosophilid flies in Camellia flowers in nature. From the present and previous studies, it is assumed that aggregation (or production of clutches of more than one egg) is related to the use of fermenting or decayed resources; aggregation might increase larval survival and/or performance under the presence of molds or microorganisms.