Oviposition site selection and its influencing factors of the litchi fruit borer，Conopomorpha sinensis Bradley（Lepidoptera： Gracillariidae）on litchi fruit

【Objective】 In this study，the oviposition site of litchi fruit borer（LFB）， Conopomorpha sinensis Bradley adults on litchi fruit surface and the influencing factors were investigated to provide scientific basis for the regulation and control of oviposition behavior of LFB.【Method】 Through laboratory test and field investigation，the amount of eggs of LFB on litchi was compared in different regions of litchi fruit surface. The oviposition selection experiment was conducted to investigate the oviposition attraction effects of different regions of litchi fruit surface and the influence of shape and odor on oviposition selection of LFB on litchi fruit surface.【Result】 The results of laboratory test and field investigation showed that LFB adults tended to lay eggs on the litchi fruit pedicle，and the number of eggs laid on this region accounted for 65.87%-90.29% of total eggs laid on the whole fruit. The odors of different regions of the fruit surface could induce LFB adults to lay eggs，of which the odor of the region from the fruit pedicle to the fruit shoulder had strongest induction effect. The shape and surface texture had no obvious effect on oviposition site selection of LFB. When the shapes and surface textures of the litchi fruit pedicle and apex were made to be equal，LFB adults still laid much more eggs near the litchi fruit pedicle，accounting for 72.28%-75.23% of total eggs laid on the whole fruit. The odor concentration of oviposition attractant had obvious effect on oviposition site selection of LFB，and adults tended to lay eggs in the site with higher odor concentration. Among different ovipositon media，the higher odor concentration of oviposition attractant was inside the medium，the more eggs were laid by the LFB adults on the medium surface. Moreover，among different positions of the same oviposition medium，LFB preferred to lay eggs on the position where the odor of the oviposition attractant was stronger. The same situation was observed for the odor of the litchi fruit pedicle and apex. When the odor concentration of the litchi fruit apex was constant，the oviposition preference of the LFB for the litchi fruit pedicle was reduced with the odor concentration of the pedicle decreased. When the odor concentration of the pedicle decreased to a certain level，LFB adults would prefer to lay eggs on the litchi fruit apex.【Conclusion】 LFB preferred to lay eggs near the litchi fruit pedicle on fruit surface. LFB adults have oviposition selectivity to the odor concentration of oviposition attractant，preferring to lay eggs in the site with higher odor concentration. Therefore，it is suggested that the reason why LFB adults prefer to lay eggs near the litchi fruit pedicle is that the odor near the pedicle is stronger than other sites of the fruit surface.