Spatiotemporal Dynamics of Cotton Bollworms and Associated Yield Losses in Côte d’Ivoire

Abstract

Cotton is integral to the rural economy of Cote d’Ivoire, yet yield stability is increasingly threatened by shifting pest complexes. Following the recent incursion of the leafhopper Amrasca biguttula biguttula (Ishida), cotton protection strategies were reoriented toward sap-feeding pests, and renewed infestations of boll-feeding Lepidoptera were reported. This study assessed the spatiotemporal dynamics (2021-2024) of the main cotton bollworms across production areas and sowing periods and quantified their associated boll damage and yield losses. Helicoverpa armigera (Hübner) remained the most prevalent exocarpic Lepidoptera, followed by Earias spp. and Diparopsis watersi (Rothschild). Infestations of H. armigera were more severe in late sowing periods, and this species occurred throughout the cotton-growing region. In contrast, Earias spp. and D. watersi larvae were more abundant in the northeastern production area. Among endocarpic bollworms, Pectinophora gossypiella (Saunders) was more prevalent than Thaumatotibia leucotreta (Meyrick). A significant negative correlation (r = -0.45; p = 0.001) was observed between bollworm damage and seed cotton yield, underscoring the economic importance of these pests. Overall, the results highlight the need to tailor surveillance intensity and protection strategies to the prevailing species, production area characteristics, and sowing period to mitigate yield losses.