Ovipositional Stimuli of Angoumois Grain Moth (Lepidoptera: Gelechiidae), a Primary Pest of Stored Grains

Abstract

Ovipositional preferences of Sitotroga cerealella (Olivier) were measured in the laboratory to characterize the stimuli eliciting oviposition in this widespread pest of stored grains. Substrates used for oviposition included grains presenting both physical and chemical stimuli as well as surrogates presenting only physical stimuli. Chemical factors associated with grains stimulated oviposition, but physical stimuli, primarily the presence of crevices, were of much greater importance. Moths reared for approximately 15 generations in the laboratory were less sensitive to grain factors than were moths more recently collected from the field. Experiments with surrogrates presenting a precisely defined range of crevice sizes confirmed that ovipositional response increased as crevice size narrowed. The results suggest that factors influencing habitat selection are probably very important in this insect because of indiscriminate oviposition on substrates that present appropriate physical stimuli but are entirely unsuitable for larval consumption.