Development, Fecundity and Prey Consumption of Exochomus Nigromaculatus Feeding on Hyalopterus Pruni

Abstract

Development, survival and reproduction of Exochomus nigromaculatus (Goeze) were studied in the laboratory at four constant temperatures from 20degreesC to 35 +/- 1degreesC in 5degreesC increments, 60 +/- 5% r.h. and 16 h of artificial light (5000 lux). Development time from egg to adult ranged from 22.4 days at 20degreesC to 10.6 days at 35degreesC, and required 278 degree-days above a threshold estimated to be 9.11degreesC. Survival was highest at 25degreesC and lowest at 35degreesC. Longevity of females declined significantly with increasing temperatures, ranging from 120.7 days at 20degreesC to 46.6 days at 35degreesC. Mean generation time became shorter with increasing temperatures. The intrinsic rate of increase of individuals kept at 30degreesC was significantly greater than that of individuals kept at the other temperatures tested. Fourth larval instars and adults of E. nigromaculatus displayed a Type II functional response to Hyalopterus pruni densities. Searching rate of fourth instar larvae and adults was similar, but handling time was shorter for female adults. Results obtained in this study showed that the optimal temperature for population growth of E. nigmmaculatus was 30degreesC and this coccinellid predator may have potential as a biological control agent for H. pruni because of its feeding capacity.