BIOLOGY OF THE PREIMAGINAL STAGES IN TROGID BEETLES (COLEOPTERA) - EXPERIMENTAL-DATA

Some aspects of larval behaviour in two species of trogid beetles, Tro x hispidus (Pontoppidan) from temperate Europe and Afromorgus tuberosu s (Klug) from tropical Africa, have been studied experimentally. From the results obtained it emerges that the rise of the newborn larvae to wards the soil surface is imputable to a simple negative geotropism. L arval food relocation also contributes to reducing aggressive interact ions at the food source. The potential range of trophic and behavioura l variation seems to be larger than that expressed in nature as a rule . This can contribute to explaining, in evolutive terms, the rare case s of transgression from a uniform trophic and behavioural pattern, wic h are probably at the origin of the evolutive success of the group as a whole.