The importance of epigeic beetles (Coleoptera) in tropical paddy fields: Example from Cameroon

Abstract

Indicators of diversity (population density, relative number of species, percentage of singletons, evenness) of ground beetles (Carabidae) and rove beetles (Staphylinidae) in rain-fed rice fields were assessed between 1995 and 1999 at Garoua in the Benue valley in North Cameroon. A total of 4369 individuals belonging to 44 species of carabids and 2109 staphylinids in 27 species were caught by means of pitfall traps. Among the carabids, five species: Menigius lucidus var. strigiceps Qued., Chlaeniostenus denticulatus elatus Erichson, Lissauchenius venator (Laferté), Pheropsophus marginatus Dej. and Abacetus crenulatus Dej. in decreasing order, were dominant. In the staphylinid group, the species Paederus sabaeus Erichson was the most common, followed by Stenus ravus Puthz and Stenus (mendicus) senegalensis Bernhauer. Shannon-Weiner and evenness indices varied marginally from year to year. Diversity values remained relatively low ( < 2.8) among each group of beetles, which indicated that paddy fields were moderately populated by this group of polyphagous predators. Features of predacious soil surface-dwelling beetles in West African rice ecosystems are discussed in the light of Integrated Pest Management concepts.