Can we exploit the joint use of entomopathogenic fungi and predatory bugs to control Tuta absoluta?

Abstract: Tuta absoluta is one of the most devasting tomato pests, and its control is particularly difficult due to its cryptic habits, short life cycle and high reproductive capacity. The predator Macrolophus pygmaeus is often used as a biocontrol agent against tomato pests, including T. absoluta. Moreover, endophytic fungi, e. g. Beauveria bassiana and Lecanicillium muscarium, can play a role in pest control. Therefore, research aimed at evaluating the effects of these two fungi on both T. absoluta and M. pygmaeus, such as: i) direct toxicity by exposing pest larvae and predator nymphs to tomato leaflets fungus-treated or untreated; ii) development rate of pest larvae and predator nymphs on fungus-inoculated or non-inoculated tomato plants; iii) preference of pest and predator adults for fungus-inoculated or non-inoculated tomato plants. Both fungi caused significantly higher mortality on T. absoluta larvae, whereas no significant effects were observed on M. pygmaeus nymphs. Development rate was significantly lower on L. muscarium-inoculated plants for T. absoluta, whereas no significant differences were found for M. pygmaeus. In olfactometer, M. pygmaeus showed a significant preference for both noninoculated plants and those inoculated with B. bassiana in comparison to plants inoculated with L. muscarium. Based on the results, the use of L. muscarium appears promising as it proved more effective against T. absoluta and, at the same time, the plants inoculated with this fungus were less attractive to M. pygmaeus. However, these results should be validated in the field to implement the best control strategy.