Performance of three Trichogramma species as biocontrol agents on Spodoptera frugiperda eggs

Spodoptera frugiperda (JE Smith) (Lepidoptera: Noctuidae) is one of the most polyphagous and migratory pests posing a great threat to crops. The Trichogramma species (Hymenoptera: Trichogrammatidae) play an important role in dampening pest oscillations. In this study, we examined the performance of three egg parasitoids, T. chilonis, T. dendrolimi and T. pretiosum, to control S. frugiperda. Indoor experiments indicated significant differences in fecundity and female proportion between T. chilonis, T. dendrolimi and T. pretiosum. However, no significant differences were observed in developmental duration and female parasitic capacity. Field trials were carried out to clarify their control efficiency. Results showed that the parasitism rates of three parasitoids ranged from 10.7% to 31.4%, without significant differences. Moreover, field release of parasitoids resulted in significant decreases in damage rate (the ratio of infested plants) and damage index. A positive correlation was revealed between temperature (14.5-24.5 degrees C) and parasitism rate of T. chilonis. In contrast, the relative humidity (66%similar to 77%) did not affect their performance. Taken together, all three Trichogramma species can be used as potential agents to control S. frugiperda, which undoubtedly lays a solid foundation for their application.