Influence of Stimuli from Camellia japonica on Ovipositional Behavior of Generalist Herbivore Epiphyas postvittana
1998
Foster, S. P. | Howard, A. J.
Stimuli from the plant Camellia japonica that influence the host-finding and acceptance behaviors of adult females of the generalist herbivore Epiphyas postvittana were investigated. In a binary choice test in a small (35-cm-diam.) arena, females discriminated between a plant and a laminated card model, laying many more eggs on the plant. Observations of females showed that the greater number of eggs laid on the plant were primarily due to on-plant behaviors, with females spending significantly more time per visit on the plant than on the model. Interestingly, females landed a similar number of times on the plant as on the model, suggesting that volatile chemicals from the plant did not influence host-finding. This observation was further supported by wind-tunnel studies, in which females showed little or no upwind flight activity in response to plants and laid similar numbers of eggs on upwind and downwind plants. Leaf surface texture, a combination of smoothness and fine structure (consisting of the midvein and other raised leaf veins), was found to stimulate egg laying by females. Methanol, dichloromethane, and pentane extracts were made of the waxes on the leaf surface. Of these three extracts, only the nonpolar (pentane) one stimulated egg laying by females. Although we did not find a role for volatile plant chemicals in host finding, they appeared to stimulate increased egg laying when the female was on the plant. It appears likely that these chemical and tactile stimuli in C. japonica are general stimuli, which may be found in a large number of plants and, in combination with the feeding preferences of the larva, may explain the generalist herbivorous nature of this pest.
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