Habitat selection, reproduction and survival of two small carabid species on arable land: a comparison between Trechus secalis and Bembidion lampros

In central Sweden, teneral adults of the strictly larval‐overwintering carabid beetle Trechus secalis Paykull started emerging during mid‐June and bred in midsummer (July). In contrast, the strictly adult‐overwintering carabid Bembidion lampros Herbst bred in early summer (June), and the new‐generation emerged in late summer (August). Both species appeared to be univoltine and had a short period of sexual activity (2–3 months). Their main oviposition periods did not overlap, and gravid B. lampros contained a higher mean number of eggs than did gravid T. secalis . Conversely, T. secalis had a longer oviposition period than B. lampros . Prereproductive B. lampros accumulated in high densities along field edges prior to hibernation. The cereal fields appeared to be optimal for reproduction and larval development of both species. Trechus secalis also reproduced in adjacent uncultivated habitats, whereas B. lampros did not. Trechus secalis larvae were completely subterranean, whereas B. lampros larvae were partly surface active. The adaptive significance of their reproductive tactics and habitat preferences as adults and the suitability of cereal fields as habitats for reproduction and survival of populations are discussed.