Study of a New Biological Control Method Combining an Enteropathogen and a Chemical Insecticide Against Solenopsis invicta (Hymenoptera: Formicidae).

Solenopsis invicta (Buren; Hymenoptera: Formicidae) is a species that has invaded China in recent years. Currently, S. invicta is mainly controlled by chemical treatment, though long-term use of chemical pesticides can cause serious environmental pollution. In this study, a microbial insecticide formulated for the control of S. invicta was screened for laboratory toxicity and field efficacy. The co-toxicity coefficients (CTCs) of the combination of Beauveria bassiana and thiacloprid at various mass ratios were 356.53, 251.20, 182.50, 215.03, and 143.19. When B. bassiana powder and thiacloprid were mixed at a mass ratio of 8: 2, the CTC was 356.53, demonstrating a very significant synergistic effect. According to a field efficacy test, at 3 d after treatment, the efficacy of mound injection was significantly better than that of mound drenching. In this study, the insecticidal activity of pathogenic microorganisms against S. invicta was markedly enhanced by using a self-designed apparatus for mound injection of the tested preparation of a complex containing a pathogenic microbe. The results show that S. invicta can be sustainably controlled while ensuring the safety of the environment. The findings are a good reference for the promotion and application of safe control of S. invicta in the future.