Climate-specific dynamics of fall armyworm on maize: Implications for pest monitoring and management

Abstract

Effective management of the fall armyworm (FAW), Spodoptera frugiperda (J. E. Smith) (Lepidoptera: Noctuidae), requires robust monitoring and surveillance in newly invaded regions. This study investigates the population dynamics and infestation levels of the FAW, Spodoptera frugiperda, on maize farms in Togo's Guinean and Sudanese climatic zones to improve pest management strategies. Male FAW moths were monitored using pheromone traps over 15 months, and larval densities and plant damage were assessed on 100 maize plants per farm. Results revealed more frequent moth captures in the Sudanese than in the Guinean climate zones (2.77 ± 0.16 vs. 2.05 ± 0.13). During the major rainy season (June to August), captures peaked in the Sudanese zone (5.28 ± 0.52) and were substantially more frequent compared to the Guinean zone (3.77 ± 0.55). No significant differences were observed during the minor rainy season (September to November), while in the dry season (December to May), captures were higher in the Guinean zone (0.54 ± 0.07) than in the Sudanese zone (0.24 ± 0.05). Despite similar larval densities, plant damage was greater in the Guinean zone during the major rainy season, likely due to positive correlations between adult captures, larval counts and plant damage in this region. Conversely, no such correlations were observed in the Sudanese zone. Additionally, maize stage-specific analyses in Lomé and Toaga found no correlations between FAW captures, larval densities or damage. These findings highlight the need for climate-specific pest management strategies rather than uniform national approaches, supported by linear regression models for each region.