Assessment of the suitability of three native Trichogramma species for biological control of Tuta absoluta in China

Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae) is an invasive alien species that causes major losses in the Chinese tomato industry. Historically, insecticides have been used extensively to control T. absoluta, but resistant populations have been frequently detected. Biological control represents a sustainable and effective method with which to prevent and control T. absoluta. Egg parasitoids from the family of Trichogrammatidae (Hymenoptera) have been identified as potential biological option for controlling of T. absoluta. In the present study, we aimed to identify local dominant Trichogramma species that exhibited the best biological control ability against T. absoluta in China. To accomplish this, we compared the selectivity and number of offspring of three Trichogramma species to T. absoluta by performing host preference experiments in the laboratory. We also evaluated the fitness of Trichogramma against T. absoluta by assessing the parasitic ability and behavior of their offspring on different hosts. Compared with Trichogramma chilonis and Trichogramma dendrolimi, Trichogramma ostriniae exhibited a significantly greater preference to T. absoluta eggs and produced a higher number of offspring. The emergence rate and proportion of female T. ostriniae parasitizing the eggs of T. absoluta was higher than that of the other two Trichogramma species, the rate of T. ostriniae offspring deformity was only 3.00%. In addition, T. ostriniae has shortest immature stage and the longest adult stage among the three species. In conclusion T. ostriniae can be a promising native biological control agent against T. absoluta in China.