Phenology and spatial modeling of native and exotic parasitoids for biological control of fall armyworm (Spodoptera frugiperda) in Africa under changing climate conditions

Salim, M.A., Tonnang, H.E.Z., Greve, K., Borgemeister, C. & Goergen, G. (2025). Phenology and spatial modeling of native and exotic parasitoids for biological control of fall armyworm (Spodoptera frugiperda) in Africa under changing climate conditions. Biological Control, 211: 105929, 1-31.

The fall armyworm (Spodoptera frugiperda) poses a significant threat to African agriculture, particularly maize crops, necessitating sustainable pest management solutions. This study evaluates the phenology and effectiveness of both native (Chelonus bifoveolatus, Cotesia icipe, and Charops sp.) and exotic (Chelonus insularis and Cotesia marginiventris parasitoids species as biological control agents under various temperature regimes and future climate scenarios. Utilizing the Insect Life Cycle Modeling (ILCYM) software, the developmental stages, mortality rates, fecundity, life table parameters, and spatial dynamics of these parasitoids were analyzed across a temperature range of 20 °C to 32 °C. The results reveal that optimal development and minimal mortality for these parasitoids generally occur between 25 °C and 30 °C. Native species like Cotesia icipe and Chelonus bifoveolatus demonstrated robust adaptability and higher reproductive rates under these conditions. In contrast, Chelonus insularis, an exotic species, exhibited a narrower temperature tolerance but showed potential for increased reproductive success under future climate scenarios, particularly in southern and eastern Africa. Spatial modeling highlighted that Cotesia icipe exhibited high oviposition rates in East Africa, while C. insularis showed similar potential across central and southern Africa, making these regions prime candidates for targeted biological control interventions. Conversely, regions in southern Africa displayed higher senescence rates for certain parasitoids, such as Cotesia icipe, suggesting potential limitations in their long-term effectiveness in these areas. Climate change projections under Representative Concentration Pathway (RCP) scenarios 2.6 and 8.5 predict significant shifts in the distribution, activity, and establishment risk of both native and exotic parasitoids by 2050 and 2070. Native species like Cotesia icipe and Charops sp. are expected to maintain or expand their effectiveness across regions, while C. insularis may become increasingly important in new areas as climatic conditions evolve. This research provides critical insights into the phenology and spatial ecology of parasitoid species, emphasizing their role in integrated pest management necessary under climate change. The findings underscore the importance of selecting climate-resilient parasitoids for sustainable biological control programs across diverse African agro-ecological zones.