Olfactory and biophysical assessment of the oviposition stimulating potential of host and non-host plants for the yellow peach moth, Conogethes punctiferalis (Lepidoptera: Crambidae)

Abstract

Oviposition responses of gravid Conogethes punctiferalis (Guenee) females to various parts of 4 host and 14 non-host plants were assessed in laboratory cage tests, where females were not allowed to contact the materials tested. Normal responses were observed to typical host plants. Unexpectedly, the females showed normal oviposition responses to 13 species of non-host plant parts, even though some were underground parts. On the other hand, no or slight responses were observed to potato tubers and leaves. In choice tests between different parts of the same host plant, females always preferred young fruits. Females preferred young peach fruits to turnip taproots, but no preference was seen between codling and turnip, and they unexpectedly preferred Brussels sprout buds to codlings. However, when females were allowed to contact plant materials, they laid few eggs on the host and non-host leaves that attracted them in the olfaction stimulus assays. Egg distributions on codling and chestnut were concentrated at the stem cavity or calyx end and spiny involucre, respectively. These results indicate not only that oviposition was induced by plant olfactory stimuli, but also that various non-host plants potentially stimulate oviposition. Even in host plants, biophysical stimuli also restrict oviposition, suggesting that the real host range for oviposition may be narrower than that expected from laboratory assessments based on olfactory responses of female moths.