Abstract: Elite Trichogramma species and strains for controlling Plutella xylostella were screened by comparing the differences in the parasitic ability of 17 strains of T. chilonis, T. ostriniae, T. dendrolimi, and T. japonicum to the eggs of P. xylostella. The results showed that all the four Trichogramma species could parasitize P. xylostella eggs, but their parasitic ability differed, ranked as: T. chilonis＞T. ostriniae＞T. dendrolimi＞T. japonicum. Among the 17 strains, T. chilonis Tc-1 strain had the strongest parasitic ability, with parasitism rates of eggs and egg cards of 73.01% and 98.89%, respectively. The emergence rate and female wasp rate from the parasitized P. xylostella eggs were more than 85%. Field tests using T. chilonis Tc-1 strain for control of P. xylostella showed that P. xylostella population in the wasp-released fields was significantly reduced and fluctuated less. Population of P. xylostella declined more with the increase of Trichogramma release times. After four times of Trichogramma release, the population size of P. xylostella was 278 per 100 plants, which was 89.85 % lower than that in the control fields. This proves that the T. chilonis Tc-1 strain is an excellent strain for controlling P. xylostella and has a broad prospect of application.

Key words: Trichogramma, Plutella xylostella, parasite potential, field control efficacy evaluation