Biology of Chrysocharis pentheus, an Endoparasitoid Wasp of the Citrus Leafminer Phyllocnistis citrella Stainton

The biology of Chrysocharis pentheus (Walker) (Hymenoptera: Eulophidae), the most abundant endoparasitoid of Phyllocnistis citrella Stainton (Lepidoptera: Gracillariidae) in Ehime prefecture, Japan, was studied under laboratory and field conditions. The mean immature developmental time and adult longevity at different temperatures (22 to 31°C) under 50-70% RH decreased as the temperature increased, and females survived longer than males. The developmental threshold of male and female was 8.9°C and 11.9°C, respectively. The effective accumulative temperature (thermal constant) for males and females from egg to adult was 181.8 and 238.1 degree-days, respectively. C. pentheus appeared to be a synovigenic species. The offspring sex ratio from females provided with males was 73.8% males and 26.2% females. Presumably, mated females began oviposition 1-2 days after emergence and continued for up to 40 days. Females laid a mean of 118.2±10.10 eggs each, and their longevity reached 32.3±0.30 days at 27±1°C, 50-70% RH. The intrinsic rate of natural increase (rm) was 0.144. Host feeding or stinging without oviposition killed 65.7±8.65 P. citrella larvae per female. Oviposition in the field was highest (62.7%) on the third instar larva of P. citrella, with the rest on the prepupal stage (37.3%), showing a significant preference for third instars. The sex ratio (M:F) of C. pentheus reared from the third instar larvae of host and pupae was 3.3:1.0 and 1.0:3.0 respectively.