Was Hopkins right? Influence of larval and early adult experience on the olfactory response in the granary weevil Sitophilus granarius (Coleoptera, Curculionidae)

The induction of olfactory preferences by larval and early adult experience for odour from wheat or maize grain was examined for the granary weevil Sitophilus granarius L. in a static four‐chamber olfactometer. Weevils were reared on either wheat or maize grain and received different early adult experience. It turned out that weevils that were reared in wheat and isolated as pupae from the kernels preferred wheat odour in the olfactometer when they emerged without any odour or in the presence of maize odour. Weevils that emerged in the presence of wheat odour preferred both wheat and maize odour. When weevils emerged normally as adults from the wheat kernel in which they developed, maize odour was avoided. In contrast, for weevils that were reared in maize no preferences were found in most experiments. Only weevils that emerged in the presence of wheat odour preferred the maize odour over the controls. These results demonstrate that host‐selection behaviour in S. granarius weevil is shaped by experience according to the Hopkins host‐selection principle or the chemical legacy hypothesis and the neo‐Hopkins principle.