Responses of the fall armyworm, Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae) to host plant cues and sex pheromones in Africa

Abstract

The fall armyworm, Spodoptera frugiperda, an invasive noctuid pest, has rapidly spread across continents, posing a significant threat to agriculture. This thesis delves into the intricate relationship between S. frugiperda and its host plants, as well as the role of olfaction and pheromones in shaping its behavior. The primary aim was to explore semiochemical-based methods for monitoring and controlling this pest. The study began by unraveling how olfaction guides S. frugiperda's host selection process, revealing distinct preferences based on volatile chemical profiles. These findings open doors to effective control strategies, such as intercropping, leveraging the insect's innate preferences. Early detection is pivotal in pest management, and pheromone-based monitoring plays a crucial role. However, the effectiveness of synthetic pheromones has varied across regions. This research identified specific commercial lures, trap designs, and optimal trap heights for an improved monitoring system tailored to the African context, enhancing early pest detection. Additionally, the thesis explored potential geographical and strain-specific variations between rice and corn strain populations of S. frugiperda in Africa. Analysis of female moth pheromones and male moth responses revealed slight differences in pheromone production between strains but confirmed the possibility of inter-strain mating, shedding light on reproductive dynamics.