Impact of Altitude on Maize Infestation by Fall Armyworm (Spodoptera frugiperda) in Nyiragongo Territory, Democratic Republic of Congo

The fall armyworm (Spodoptera frugiperda) is a major pest of maize in the Democratic Republic of Congo, significantly affecting yields. This study aims to evaluate the incidence and severity of infestation based on altitude and crop associations in the Nyiragongo territory (North Kivu) from May 2022 to October 2023. Observations were conducted in ten maize fields located between 1500 and 1950 meters above sea level. The average incidence ranged from 38% in the lowest areas (< 1600 m) to 17% in the highest areas (> 1850 m), with a statistically significant difference (ANOVA, p = 0,01). The severity of the damage, measured using a visual score (Davis scale 1–9), also decreased with altitude (mean = 4,8 at low altitude against 2,1 at high altitude). In contrast, the equivalent density coefficient (EDC) did not show a significant effect on incidence (p > 0,05). Higher altitudes (> 1850 m) lead to a significant reduction in the incidence and severity of fall armyworm infestations, likely due to cooler temperatures that slow down larval development. The tested intercropping associations did not have a measurable effect on the incidence of infestation in this region. These results suggest that growing corn at higher altitudes or selecting varieties adapted to these areas could reduce losses related to the fall armyworm. Further research on the interaction between microclimatic conditions and natural enemies is recommended to improve integrated pest management strategies. Keywords: Spodoptera frugiperda, maize, incidence, altitude, Nyiragongo, Democratic Republic of Congo