[Effects of temperature on the development and fecundity of Diachasmimorpha longicaudata (Ashmead)]

A laboratory experiment was conducted to investigate the growth and reproduction of Diachasmimorpha longicaudata (Hymenoptera: Braconidae) reared on the 3rd instar larvae of Bactrocera dorsalis (Diptera: Tephritidae) at 15, 18, 21, 24, 27, and 30 degrees C. Within the range of test temperatures, the generational development time shortened with increasing temperature, from about 45.7 days at 15 degrees C to 15.2 days at 30 degrees C. Excessively low or high temperature had definite inhibition effect on the development of D. longicaudata. At 15 degrees C and 30 degrees C, the survival rate of D. longicaudata at immature stages (i. e. , from egg to adult) was 10.2% and 31.3%, respectively; while at 24-27 degrees C, the survival rate was above 50%. The longevity of D. longicaudata decreased with increasing temperature, and that of the females was usually longer than that of the males. The fecundity of D. Iongicaudata was the highest (74.2 progenies) at 24 degrees C, followed by at 27 degrees C (53.4 progenies), at 21 degrees C (35.7 progenies), and at 18 degrees C (31.6 progenies). At 15 degrees C and 30 degrees C, no more than 20 progenies were observed. At 15-24 degrees C, the female/male ratio increased with increasing temperature, being the highest (0.59) at 24 degrees C; at 21-27 degrees C, females predominated in the progenies populations. The intrinsic increase rate (r(m)) was the highest (0.1318) at 27 degrees C, followed by at 24 degrees C (0.1239), at 21 degrees C (0.0747), at 30 degrees C (0.0318), and at 18 degrees C (0.0187). At 15 degrees C, the intrinsic increase rate and population trend index were -0.0240 and 0.8, respectively, indicating that the population at this temperature presented a negative increasing trend. The favorite temperature range for the development and reproduction of D. longicaudata was from 24 degrees C to 27 degrees C.