Host selection and location behavior of Aprostocetus prolixus LaSalle et Huang (Hymenoptera:Eulophidae), an egg parasitoid of Apriona germari (Hope) (Coleoptera:Cerambycidae)

In this paper, the host selection and location behavior of Aprostocetus prolixus lasalle et Huang was investigated systemically. Many studies showed that volatiles of host plant-insect complex could attract the parasitoid. In order to determine the source of the attractive volatiles within the host plant-insect complex, we examined separately the volatiles that Morus alba twigs with different treatments (healthy twigs, mechanically damaged twigs, system twigs, and twigs infested either by feeding or by oviposition of Apriona germari), faeces of A. germari, and both sexes of the host insect A. germari. The results revealed that the twigs in all treatments attracted the wasp significantly. In addition, the volatiles from egg-laid twigs were the most attractive compared with those from other differently treated twigs. Odours from faeces of host insect elicited a positive response of A. prolixus, but volatiles neither from male nor from female host insect acted as attractants. The effect of A. germari walking traces on microhabitat acceptance behavior of the wasp was not found in open arena assays, whereas the kairomones from feaces of A. germari were demonstrated to be important in the process of microhabitat acceptance for parasitoids by Petri dish bioassays. In choice tests, A. prolixus preferred egg-deposited M. alba twig to healthy or feeding-damaged twig, but the significant differences in the choice of host units among different host plants were not detected. There were infochemicals involved in host recognition by the egg parasitiod on the surface of host-unit.