Behavioral Strategy Of Mating And Oviposition Of Adult Ophraella Communa

Ophraella communa LeSage (Coleoptera: Chrysomelidae) is an important and specific natural enemy against invasive weed, common ragweed(Ambrosia artemisiifolia). The morphological characteristics, the reproductive behavior recharacteristic, sexual selection, mating and oviposition behaviors of adult O. communa were studied in this article. The results showed that the external morphological characteristics of male are similar to those of female and the size of male is smaller than that of female. There is a "V" stripe at the end of genital abdominal segment of male, but not "V" stripe at the end of genital abdominal segment of female. Adult beetles have a sex maturity period, and then they can mate each other. The pre-copulation duration of male (2.7±1.2 d) is longer than that of female (0.9±2.1d). There is a pre-ovipositional duration in female before it begins to lay eggs. Adults maintained a higher mating rate from 8:00 until 21:00, and revealed a higher number of eggs laid at 12:00 to16:00 compared with at any other stages daily. In the early 30 days, especially in 5 days after mating, female beetles laid most eggs, and then few eggs were observed at other stages. Female beetles prefer to mate with the males whose frontal spot, forewing and metaleg femur were longer compared with any other males. Male beetles prefer to mate with 8-day-old virgin females, and female beetles like to mate with 12-day-old virgin males. Copulation time of adult beetles was affected by temperature, but there is not significant relationship between copulation time and adult's size or sex ratio. Copulation time was decreased with the increasing temperature. The longest copulation time was noticed at the low temperature of 10℃, which was 217.7±5.8 min, and the shortest was observed at the high temperature of 35℃, was only 36.4±5.9min. The copulation of male beetles was significantly increased and that of female beetles was significantly decreased under female biased sex ratio. However, the copulation frequency of male beetles was significantly decreased under male biased sex ratio, and the copulation frequency of female beetles reached a maximum under the sex ratio of 1(?):3(?).Female beetles felt the surface of leaves by antennae and mouthpart in the process of searching oviposition site. Female beetles like to lay eggs on the reversed side of the mid and basal leaves at early and mid damage stages, but the number of eggs was observed in the healthy and serious damage plants.