Biodiversity of ground beetles (Coleoptera: Carabidae) in Canadian agricultural soils

Abstract

In Canada, ground beetles (Carabidae) are abundant and diverse in agricultural ecosystems. Adults of all species are well characterized, but only 10% are known in the immature stages. In a typical agricultural site, one could find 40 to 60 species. While the ground beetle species composition consists mainly of native species in agriculture sites in the Prairie regions, a mixture of local and accidentally introduced species is the norm elsewhere. Although the diversity of introduced European species is not as great as that of native of ground beetles, the absolute number of European species may dominate an agricultural site. The basic biology and habitat requirements of almost all species occurring in agricultural habitats are known. Each species of beetle has special requirements based on soil type, moisture, pH, and light exposure. They are excellent indicators of habitat modification and of the quality of the environment. Although, most species of ground beetles are predators or scavengers, some are seed feeders. Because of their positive contribution to agricultural ecosystems, maintaining and developing their diversity by providing refuge habitats is recommended. Cropping sequence and type of crop influence ground beetle populations. More important, pesticides of all kinds reduce to various degrees the number of species and specimens. Female fecundity is a most sensitive test of sublethal pesticide effects on groun d beetles and should be considered in future studies of non-target insects. Key words: Ground beetles, carabidae, diversity, ground beetles and agriculture, ground beetles and pesticides, ground beetle extirpation