Effect of temperature on the life history of Encarsia bimaculata (Hymenoptera: Aphelinidae), a parasitoid of Bemisia tabaci (Hemiptera: Aleyrodidae)

Encursia bimaculata (Heraty & Polaszek) is an abundant parasitoid of Bemisia tabaci in southern China. The effects of constant temperatures on a range of life history traits, including development, survival of immatures, longevity and reproduction of adults, were studied in the laboratory. The developmental period from egg to adult ranged from 34.3 +/- 0.4 d at 20 degrees C to 8.7 +/- 0.6 d at 32 degrees C, A total of 181.4 +/- 2.4 degree-days were required to complete development with a lower developmental threshold of 11.6 +/- 0.3 degrees C. The survivorship of E. bimaculata from 2(nd) instar to adult varied from 81.3 +/- 1.7% at 20 degrees C to 91.0 +/- 1.8% at 26 degrees C. Average adult female longevity was 8.4 +/- 0.7 d at 20 degrees C and 5.4 +/- 0.4 d at 32 degrees C, and daily production of offspring peaked at 29 degrees C with 4.5 offspring per female. The maximum oviposition occurred three days after adult emergence at 23, 26, 29 and 32 degrees C, and four days at 20 degrees C. Total number of offspring produced per female varied from 24.3 +/- 2.0 at 32 degrees C to 29.3 +/- 12.9 at 20 degrees C. The maximum intrinsic rate of increase (r(m))was 0.2163 +/- 0.013 at 29 degrees C, followed by 0.2062 +/- 0.022 at 32 degrees C. Results indicate that E. bimaculata reaches its maximum biological potential at temperatures ranging from 26 degrees C to 32 degrees C with 29 degrees C being the optimal temperature.