Abstract:  As the most successful biological pesticide, Bacillus thuringiensis (Bt) insecticide has been used to control pests in agricultural production for about 80 years. The wide and successful use of Bt insecticide due to its specificity, safety and efficiency has greatly reduced the application rate of chemical pesticides, making a huge contribution to environmental protection. However, due to long-term application, some target insect pests have gradually developed resistance to Bt. In this article, the research advances in insect humoral immunity and the mechanisms of Bt resistance in insects were summarized. Previous studies suggested that the blockage of toxin activation and/or the mutation or reduction of toxin receptor are the main causes of the development of Bt resistance in insect pests. However, in recent years, more and more studies have shown that Bt resistance in insects is also associated to their immune system, especially to humoral immune pathways such as Toll, IMD and proPO-AS. Therefore, we reviewed and inferred the main pathways in which the humoral immune system is involved in the development of Bt resistance in insects. The IMD immune pathway may be involved in regulating Bt resistance in insects through the MAPK signaling pathway, or insects may counteract sepsis caused by the destruction of midgut tissue by Bt through multiple immune responses and promote midgut tissue healing through the JNK signaling pathway, thereby increasing their resistance to Bt. Research with the humoral immune system as the breakthrough point could be a new direction for further exploring the mechanisms of Bt resistance in insects.

Key words: Pests; Bacillus thuringiensis; humoral immune system, Bt resistance, resistance mechanisms