Abstract: The fruitpiercing moth, Oraesia emarginata (Fabricius), is an important pest for fruits and can be used as model insect for olfactory study, because its larvae and adults feed on different host type. In order to understand the morphological and biological characteristics of O. emarginata, its external morphological characters, developmental duration and the circadian rhythm of different developmental stages were studied through artificially feeding in the controlled conditions and monitoring with infrared camera. The results showed that different larval instars could be differentiated by body color, the color, location and number of spots in the body, and the number of abdominal feet. The genital pore in the pupae, and moth antennae could be used for sex identification. The life time of O. emarginata was 53.18±1.70 d and the survival rate was 63.62%±2.15% under laboratory conditions. Compared with other stages, larva had the longest developmental duration and lowest survival rate while the egg had the shortest developmental duration and highest survival rate. Male moths lived significantly longer than female moths (P=0.008). The developmental duration of the 6th instar larva (5.29±0.15 d) was significantly longer than that of other larval instars (P<0.001). The body length and body weight of larvae in the middle time of an instar were significantly larger than those before ecdysis and after ecdysis for the same instar (P≤0.037). There were no significant differences in the body length and body weight between the larvae after ecdysis of a later instar and the larvae in the middle time of the former instar (P≥0.106). The proportions of hatching, ecdysis and pupation of larvae during light period were higher than those during dark period. However, the rates of moths in flight and oviposition under dark condition were higher than those under light condition. The flight frequency of moths decreased when the dark time prolonged and the moths in flight during light period were mostly found in the first hour of light period. The moth copulation was only found at 3-5 h after dark. These results will not only help to design more efficient pest control methods, but also provide knowledge for using the insect as a model for olfactory study.

Key words: Oraesia emarginata, morphology, growth and development, life history, circadian rhythm