Juliana Amaka Ugwu

PhD Overview

The project investigated the gut microbiome of the fall armyworm (Spodoptera frugiperda), an important invasive and highly polyphagous pest of maize and other crops, with the aim of understanding the diversity, composition and potential functional significance of its associated microorganisms. The research initially characterized the gut microbiome of S. frugiperda larvae collected from maize in Nigeria using high-throughput 16S rRNA sequencing, revealing a diverse microbial community comprising numerous bacterial taxa, with Proteobacteria, Firmicutes and Bacteroidetes among the dominant groups. Building on this baseline, subsequent studies examined the influence of host-plant diet on the gut bacterial community. Experiments involving different monocot and dicot plant diets demonstrated that host-plant type significantly influenced bacterial richness, diversity, community structure and distribution. The studies further showed that chemical and nutritional characteristics of plant diets contributed to differences in the composition of the fall armyworm gut microbiome, while functional prediction identified microbial activities associated with processes such as chemoheterotrophy, fermentation and degradation of aromatic compounds.

Collectively, the research demonstrated that the fall armyworm possesses a diverse and dynamic gut microbiome and established host-plant diet as an important driver of its gut bacterial community. The findings provide important insights into the biological relationship between S. frugiperda, its host plants and associated microorganisms, and contribute to understanding how microbial communities may be involved in the insect’s nutrition, adaptation and ecological interactions. By identifying diverse microbial taxa and their predicted functional capabilities, the project provides a scientific foundation for future investigation of specific microorganisms and microbial metabolites as potential resources for biological control, crop protection and sustainable fall armyworm management. The research therefore contributes to the development of microbiome-informed approaches to integrated pest management and offers new opportunities for exploiting insect-associated microbial diversity in sustainable agriculture.