Study on Optimal Parasitoid-host Ratio of Breeding Bethylid with Larvae of Monochamus alternatus

Scleroderma guani and Scleroderma sichuanensis were bred by utilizing 2.0 cm to 3.0 cm long larvae of Monochamus alternatus.The inoculation was conducted with three parasitoid-host ratios(2:1,3:1 and 4:1),and the indexes such as infecting rate,shriveled rate of host,parasitical rate,successful parasitical rate,quantity of oviposition and the number of bethylid filial generation were determined.The results showed that 3:1 parasitoid-host ratio was the best choice for breeding these two species of ethylids regarding to each index mentioned above.The breeding efficiency ratios of the two bethylid species were 1.00:1.98:1.36 and 1.00:2.79:1.49 respectively.So the parasitoid-host ratio of 3:1 was thought to be the optimal ratio among the three treatments.