Bt GS57 Interaction With Gut Microbiota Accelerates Spodoptera exigua Mortality

Area of Science:

• Entomology
• Microbiology
• Genetics

Background:

• The beet armyworm (Spodoptera exigua) is a major global pest.
• Pathogen infections disrupt insect gut microbial balance, potentially causing death.
• The role of host gut microbiota in insecticidal efficacy of Bacillus thuringiensis (Bt) is understudied.

Purpose of the Study:

• To investigate the genome of Bt GS57 and the gut bacterial community of S. exigua.
• To determine the influence of S. exigua gut microbiota on Bt insecticidal activity.

Main Methods:

• Genome sequencing of Bt GS57.
• Analysis of gut bacterial diversity and function in S. exigua using Illumina HiSeq.
• Biological activity assays and crystal morphology analysis of Bt GS57.
• Assessment of S. exigua susceptibility to Bt following gut microbiota manipulation.

Main Results:

• Bt GS57 genome characterized (6.17 Mbp, 35.66% G+C), containing cry and vip genes.
• Bt GS57 produces biconical crystals and exhibits insecticidal activity (LC50 = 0.339 mg mL-1).
• Bt infection alters S. exigua gut microbiota, reducing diversity and increasing bacterial load.
• Loss of gut microbiota significantly decreased S. exigua susceptibility to Bt.

Conclusions:

• Gut microbiota plays a crucial role in the insecticidal activity of Bt against S. exigua.
• Bt pathogenesis mechanisms involve interactions with the host's gut microbial community.
• Findings offer new insights into Bt efficacy and insect pest management strategies.