Chemically mediated habitat recognition in shore insects (Coleoptera: Carabidae; Hemiptera: Saldidae)

Adults of 14 species of Carabidae and mixed nymphs and adults of two species of Saldidae, collected in habitats associated with a saline lakeshore, sedge fen, vernal pond, stream mud flat, salt spring, mud and sand river bank, pebble river bank, and a marine sand beach, aggregated in choice chambers above volatiles (allelochemics) collected from their habitats. In other tests adults of some carabid species responded to volatiles from habitats other than their own, and to arbitrarily selected individual components and mixtures of components of saline lakeshore volatiles. These results suggest that shore insects recognize habitat allelochemics and aggregate in areas where these compounds are emitted by resident microflora. It is proposed that some habitat allelochemics are short-range signals that indicate locations of microhabitats used by shore insects for behaviors such as feeding, mating, and resting; in contrast, long-range allelochemics allow these insects to select their habitats from a distance. This hypothesis provides a mechanism for explaining how different shore habitats are partitioned among different species of shore insects.