Abstract:

In order to explore the feasibility of combined application of two parasitoid natural enemies in pest control and provide a new idea of natural enemy utilization for biological control, Pyemotes zhonghuajia and Scleroderma guani were chosen to act on the third instar larvae of Semanotus bifasciatus simultaneously or successively. The results were shown as follows. (1) Parasitism rate and successful parasitism rate achieved 100% when the two kinds of natural enemies acted on the host simultaneously. (2) The number of breeding of Pyemotes zhonghuajia and that of Scleroderma guani were both above 70 when they parasitized the host individually, while the breeding numbers were reduced significantly when the two natural enemies were acting on the host simultaneously or successively. Consequently, it is suggested that the releasing time of Scleroderma guani should be 10 days later than that of Pyemotes zhonghuajia when the two kinds of natural enemies were utilized simultaneously in biological control of Semanotus bifasciatus, in order to reduce the probability of competing for the same host resource. The suggested strategy can not only avoid the interspecific competition of different natural enemies but also control the old-age larvae by Scleroderma guani. The results provide a theoretical basis for the combined control of boring insects by multiple natural enemies.

Key words: Pyemotes zhonghuajia, Scleroderma guani, interspecific competition, combined control, biological control