Temperature-Dependent Development and Demography of Scymnus Subvillosus (Coleoptera: Coccinellidae) Reared on Hyalopterus Pruni (Homoptera: Aphididae)

Abstract

The development, survival, and fecundity of Scymnus subvillosus(Goeze) (Coleoptera: Coccinellidae) were studied at 20, 25, 30, and 35 degrees C, 60 +/- 5% RH, and a photoperiod of 16:8 (L:D) h. (5,000 lux) under laboratory conditions. The total developmental time from egg batch to adult eclosion ranged from 22.6 d at 20 degrees C to 10.6 d at 35 degrees C. The developmental rates of the egg stage, the larval stage, and total preadult stage at different temperatures increased linearly with increasing temperature. The thermal summation of the egg stage, the larval stage, and the total preadult stage was 77.5, 145.8 and 300 degree-days (DD), respectively. The developmental threshold of the egg stage, the larval stage, and the total preadult stage was 7.4, 4.1, and 7.1 degrees C, respectively. The life history raw data were analyzed using the age-stage, two-sex life table. The intrinsic rate of increase was 0.0845, 0.1138, 0.1395, and 0.0668 d(-1) at 20, 25, 30, and 35 degrees C, respectively. The net reproductive rate was highest at 25 degrees C (R-0 = 78.7), and lowest at 35 degrees C (R-0 = 4.7). The mean generation time was shortest at 35 degrees C (T = 23.9 d). The life table data can be used for the projection of population growth and-designing mass rearing programs.