Abstract
Bacillus thuringiensis (Bt) is an important cosmopolitan bacterial entomopathogen, which produces various protein toxins that have been expressed in transgenic crops. The evolved molecular interaction between the insect immune system and gut microbiota is changed during the Bt infection process. The host immune response, such as the expression of induced antimicrobial peptides (AMPs), the melanization response, and the production of reactive oxygen species (ROS), varies with different doses of Bt infection. Moreover, B. thuringiensis infection changes the abundance and structural composition of the intestinal bacteria community. The activated immune response, together with dysbiosis of the gut microbiota, also has an important effect on Bt pathogenicity and insect resistance to Bt. In this review, we attempt to clarify this tripartite interaction of host immunity, Bt infection, and gut microbiota, especially the important role of key immune regulators and symbiotic bacteria in the Bt killing activity. Increasing the effectiveness of biocontrol agents by interfering with insect resistance and controlling symbiotic bacteria can be important steps for the successful application of microbial biopesticides.
Highlights
The Gram-positive bacterium Bacillus thuringiensis (Bt) and its toxins are used to control several orders of insects, including agricultural pests and pathogen vectors [1,2]
Native gut microbiota can stimulate the host immune system. It has been reported lepidopteran pest Spodoptera exigua can tolerate the action of Bt toxin when it contains an increased that themidgut nativemicrobiota gut microbiota ofNative bee isgut associated the stimulate upregulated expression of antimicrobial peptides (AMPs), load [40]
With the help of amidase activity, the peptidoglycan released help of amidase activity, the peptidoglycan released from intestinal bacteria was maintained at a low from intestinal bacteria was maintained at a low basal level, so that the host can avoid the overactivation basal level, so that the host can avoid the overactivation of the Toll and IMD pathway by gut of the Toll and IMD pathway by gut microbiota (Figure 2) [62]
Summary
The Gram-positive bacterium Bacillus thuringiensis (Bt) and its toxins are used to control several orders of insects, including agricultural pests and pathogen vectors [1,2]. The insect’s innate immune system consists of both humoral and cellular immune responses, produced by two major immune pathways, Toll and IMD (immune deficiency) These pathways produce which depend on the non-self recognition of microbes and the subsequent production of immune and regulate the expression of AMPs that are specific to either Gram-positive bacterial/fungal and effectors [23]. Native gut microbiota can stimulate the host immune system It has been reported lepidopteran pest Spodoptera exigua can tolerate the action of Bt toxin when it contains an increased that themidgut nativemicrobiota gut microbiota ofNative bee isgut associated the stimulate upregulated expression of AMPs, load [40].
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