Microbial allies in the gut of fall armyworm, Spodoptera frugiperda (J.E. Smith): Host-dependent bacterial diversity

Abstract

The fall armyworm (FAW), Spodoptera frugiperda, is a highly invasive pest with a wide host range, causing significant economic losses in crops such as maize, rice, and soybean. Understanding the gut microbiome of FAW is crucial as these microbial communities play vital roles in digestion, nutrient absorption, and detoxification, influencing the pest's adaptability and resistance to pesticides. This study was conducted during 2021-2022 at University of agricultural sciences, GKVK, Bengaluru, to investigate the gut bacterial communities of FAW larvae fed on maize, sorghum, and soybean. Using Sanger sequencing of the 16S rRNA gene, we identified a total of 16 bacterial isolates across the three host plants. The bacterial diversity varied significantly depending on the host, with Enterococcus and Pseudomonas being the dominant genera across all diets. On maize, the bacteria were dominated by Enterococcus and Pseudomonas (33.33% each). Sorghum-fed larvae had fewer isolates, with Enterococcus and Klebsiella being prominent (50% and 25%, respectively). Soybean-fed larvae showed similar diversity to maize, with Pseudomonas and Enterococcus dominating (50% and 33.33%, respectively). These findings suggest that FAW larvae selectively retain gut bacteria that aid in their adaptation to different host plants. This study highlights the significant impact of host plants on the gut microbiome and its potential role in FAW's adaptability and survival, providing insights into new strategies for pest management.