Abstract: Apriona germari is a primary wood boring insect pest, and Sclerodermus guani is one of the most important natural enemies of borer pests. In this paper, we reported results of developmental duration, parasitism rates, fecundity, emergence rates, and offspring sex ratios of and control efficacy under laboratory and field conditions by S. guani using larva of A. germari as host. The results show that parasitoid generation development time was about 31 d. Five d after exposure, the wasps began to lay eggs on the host, and the eggs hatched at 5 d since oviposition. Larva lasted 5 to 7 d and pupa developed for 14 to 16 d. Parasitoid-host ratios had a significant impact on the parasitism rates, fecundity, emergence rates and sex ratios of offspring wasp, whereas showed no influence on parasitic processes and developmental duration. When the parasitoid-host ratios were 1:1, 1:2 and 1:3, the parasitism rates increased with the ratios, being 66.67%, 83.33% and 83.33%, respectively. The fecundity also increased with the ratios, with 16.0, 16.57 and 22.71, respectively. However, the emergence rates decreased with the ratios, being 83.55%, 80.30% and 60.90%, respectively. The number of females in offsprings was significantly higher than that of males. Parasitism rates of A.germari larvae as high as 71.43% and 67.78% were recorded in laboratory and field, respectively.

Key words: Sclerodermus guani, Apriona germari, parasitoid-host ratios, control effect