Abstract: Egg parasitoids of the genus Trichogramma are widely used as inundative controls of Lepidopteran crop pests, and their adult longevity after emergence in the field is a significant factor for the success of Trichogramma inundation. Survival time of female Trichogramma dendrolimi, which were held in ventilated plastic tubes (5 cm in diameter and 10 cm long) attached to peach tree branches, were investigated directly under field conditions, and the influencing factors (food availability and climatic factors) were analyzed. The results showed that the median survival time of the parasitoid was significantly different in different cover crops (lucerne and natural weeds) and different trial dates (31 May, 5 June, 17 July, 24 July, 24 August and 30 August). The median survival time of female T. dendrolimi in the area covered by lucerne was significantly longer than that in the area covered by natural weeds. In all trial dates, the median survival time of the trials on 31 May and 5 June was the longest, and that on 17 July and 24 July was the shortest. The median survival time was inversely correlated with the mean temperature and relative humidity for all treatments, and it was influenced more greatly by the mean temperature. The median survival time of honey-fed parasitoids was significantly longer than that of the parasitoids not fed with honey. The presence of a peach leaf within the tube also increased survival time of honey-fed parasitoids but did not increase adult longevity of the parasitoids not fed with honey. It is so concluded that temperature and food availability are the main factors influencing longevity of female T. dendrolimi under field conditions.

Key words: Trichogramma dendrolimi, survival time, field conditions, temperature, relative humidity, food