Impact of different Trichogramma chilonis populations from sugarcane fields on parasitism of Corcyra cephalonica

Abstract

Trichogramma chilonis Ishii (Hymenoptera: Trichogrammatidae) is the most important parasitoid of sugarcane borers in China. T. chilonis are produced from either rearing on Corcyra cephalonica (Stainton) (Hymenoptera: Galleriidae) eggs in the laboratory or at factory level and released into the field to control sugarcane borers in China. Limited reports on the efficacy of different populations of T. chilonis in the sugarcane field against C. cephalonica are available. This study reports the parasitism efficacy and functional response of different T. chilonis populations against C. cephalonica under laboratory conditions. The number of eggs parasitized by the laboratory population of T. chilonis (total 57.05 eggs) on C. cephalonica was the highest among the different populations investigated; parasitism by the Baise population was the lowest (total 21.30 eggs). The parasitoid emergence rate of T. chilonis Baise population on C. cephalonica (102.16%) was the highest among the different populations, whereas that from the C. cephalonica laboratory population was the lowest (84.73%). The sex ratio (female/male) of T. chilonis laboratory population (3.51) was significantly higher than the other three sugarcane field populations. The functional responses of T. chilonis on C. cephalonica were determined as Holling type II. The search rate of T. chilonis laboratory population (1.0392) parasitizing on the eggs of C. cephalonica was higher than other Trichogramma populations, whereas the handling time (0.00809) was shorter than that of the other populations. The results from this study indicate that the origin of the population of T. chilonis can affect its parasitic ability upon C. cephalonica; therefore, further evaluation for control efficacy of different populations of T. chilonis against sugarcane borers, especially in the field, is warranted.