[Longevity and emergence rhythm of adult parasitoids of Coccobius asumai Tachikawa (Hymenoptera:Aphelinidae) introduced from Japan].

A series of feeding experiment and regular observation were conducted in laboratory to explore the effects of diet and temperature on the longevity of Coccobius azumai adults and their temporal rhythm of emergence. Diet had significant effects on the longevity of the adults. Without any diet supply, the mean longevity of the females and males was 1.5 d; but with the supplement of 20% honey water and of 20% honey water + fresh pine needles, the mean longevity reached 14.8 d and 11.3 d, and 17.3 d and 12.3 d, respectively. Temperature also played an important role on the longevity of the adults fed with 20% honey water. At 23 degrees C and 26 degrees C, the longevity of the females and males was obviously longer; while at 32 degrees C, the longevity was the shortest. At same temperatures, the mean longevity of the females was significantly longer than that of the males. In their circadian cycle, most of the females emerged from 11:00 to 15:00, but most males emerged from 9:00 to 12:00. Few females emerged after 18:00, and few males after 17:00. Most of the adult parasitoids enclosed from July to September. The amount of emerged adults peaked in July, and showed a fluctuant and descending trend in the subsequent August and September. Over 80% of the emerged adults were female in most days, and the males were always fluctuating in a low level in this period. A separate experiment showed that in the collection of the adult parasitoids, cloth shed was more superior to paper box. This study showed that limited energy was conserved in the parasitoids before adult emergence, and thus, supplementing suitable diet to newly emerged adults before release was necessary for prolonging their longevity and improving the efficiency of biological control. In Fujian and Guandong of China, there would be some potential disadvantage factors against the continuation of the parasitoid population, e.g., high temperature in summer, lack of temporal synchronization between the adult parasitoid females and their hosts (adult females of pine armored scale), and greatly high proportion of parasitoid females. Cloth shed benefited the collection of large amount of the parasitoids, being available in the biological control activities.