Analysing host location in Uscana lariophaga (Hymenoptera: Trichogrammatidae), an egg parasitoid of bruchids (Coleoptera: Bruchidae), using Cox's proportional hazards model

Abstract

AbstractUscana lariophaga Steffan is an egg parasitoid of the bruchid species Callosobruchus maculatus (Fabricius) and Bruchidius atrolineatus Pic in West Africa, which cause damage in stored cowpea (Vigna unguiculata (Leguminosae)). In a no-choice situation, the attractiveness of some odour sources to the parasitoid was studied in a simple diffusion olfactometer. Cox's proportional hazards model was used for data analysis. The results showed that cowpea beans were more attractive to naive U. lariophaga females than glass beads. Baits with host eggs were more attractive than baits without eggs. Experienced females did not perform any better than naive ones. The relationship between the inclination to fly of the parasitoids, and the baits used, was difficult to interpret. Changes in searching activity between the different weeks of experimentation were observed. Only a small part of this variation could be explained by (absolute) changes in barometric pressure.