Petit, Christophe

E-mail: cpetit@icipe.org
Tel: 254 (20) 8632175

Research Topic: Host fidelity origins in stemborers in East Africa

Objectives

In East Africa, lepidopteran stemborers are serious pests of crops, especially maize and sorghum. Most of them are oligophagous or specialist with a narrow host range and a strong taxonomic conservatism in host plant use. We would like to know the origin of the host fidelity (i.e. the propensity to reproduce on the same host species used during initial feeding) for Sesamia nonagrioides, Busseola fusca and Busseola nairobica (Lepidoptera : Noctuidae). In the literature, three epigenetic origins have been cited (pre-imaginal conditioning, neo-Hopkins principle and chemical legacy hypotheses). An alternative hypothesis supposes that feeding preferences are purely genetically determined. Therefore, for each aforementioned stemborer species, we will investigate the influence of genetic and nongenetic parental effects in evolution of two behavioural traits (feeding and oviposition) by manipulating larval diet quality (standard artificial diet or enriched with a new compound [e.g. vanillin]) within a cross-generational split-brood experiment. For each generation, olfactometer and oviposition/feeding preference tests will be carried out to follow the induction of feeding (by larvae) and oviposition (by early adults) for the purpose of detecting any genetic basis regulating the sensory experience (taste/odour) in African noctuid stemborers.