Ecology and biological control options against Spodoptera frugiperda (Lepidoptera: Noctuidae) in South Kivu, Eastern DR Congo

Spodoptera frugiperda (J.E. Smith), also known as the fall armyworm (FAW), is a major pest that causes yield losses in maize crops around the world. In the Democratic Republic of Congo (DRC), where farmers have limited access to effective control measures, the economic impact is particularly severe. The thesis provides the first data on the invasion of FAW in eastern DRC. Using a MaxEnt species distribution model, the study predicts its potential distribution based on environmental factors. The model highlights annual rainfall as the most important variable influencing its distribution. Field observations in two agro-ecological zones, Kabare and the Ruzizi Plain, reveal variable infestation dynamics influenced by local climatic conditions. The Ruzizi Plain is subject to heavy infestation due to its warmer climate. Two generations of FAW are likely to be observed in maize agro-systems in South Kivu. Analysis of planting dates also shows that late planting correlates with increased FAW larval density, frequency and severity, highlighting the need for climate-smart integrated pest management strategies to mitigate its agricultural impacts in the region. FAW management remains a critical issue for smallholder farmers in Africa. Although cultural and mechanical methods are used, synthetic pesticides remain popular on farms. Biological control, seen as a sustainable alternative to hazardous pesticides, has been addressed through a monitoring system to assess the natural enemies of FAW. The system includes trapping, visual observation of predators, and the collection of larvae and eggs for parasitoid studies in Kamanyola and Kabare. Ten parasitoid species have been identified, with Telenomus remus having a high rate of egg parasitism and Coccygidium luteum dominating larval parasitism. The abundance of predators such as ants, earwigs, and ladybirds varied according to the growth stage of the maize. Predatory insects were most abundant at the four fully unfolded leaf stage (V4), which coincides with high densities of FAW larvae. Maize fields were also sampled for FAW larvae infected with entomopathogenic fungi. Morphological and phylogenetic analyses confirmed that the fungi were of the species Beauveria bassiana. Three isolates (P5E, KA14, and PL6) were obtained from both FAW and earwig carcasses and compared with a commercial strain (GHA) and a local strain (BGx). The results showed significant mortality (around 70%) with the GHA, KA14, and PL6 isolates. An early warning system based on weather forecasts is needed to warn farmers of pest invasions and planting dates. Training farmers in natural enemy identification, pest knowledge, and the effective use of biological control agents is essential for the successful implementation of an integrated approach to FAW control in the DRC. Biological control is an essential component of integrated pest management for FAW in South Kivu. The results of this thesis advance knowledge of FAW invasion in Africa and provide the first data on macro- and micro-organisms as biological control agents in the DRC.