On-Farm Assessment of Spodoptera frugiperda (Lepidoptera: Noctuidae) Infestation and Damage to Early-Whorl and Late-Whorl Maize in a Southern Guinea Savanna Agro-Ecology

Abstract

Maize, Zea mays L. is an important cereal crop in Nigeria whose production has, in recent times, been constrained by the fall armyworm, Spodoptera frugiperda – a highly destructive trans-boundary and euryphagous lepidopterous insect pest. Information on the susceptibility of maize to infestation and damage at different stages of development will aid development of appropriate integrated pest management strategies for S. frugiperda but this is scanty in major maize-growing agroecological zones of Nigeria. To bridge the knowledge gap, this study assessed S. frugiperda infestation and damage severity on early and late-whorl maize. In Kwara State, Ilorin-south and Moro Local Government Areas (LGA) located in the southern guinea savanna agro-ecological zone were purposively selected. In each LGA, two farms with early-whorl (1 – 3 weeks old) and two with late-whorl (5 – 7 weeks old) maize plants were randomly chosen. On each farm, 20 plants were randomly sampled and assessed for presence or absence of larval infestation and frass, and for foliar-damage-severity using standard-rating-scale of zero to five. Irrespective of developmental stage, plants were generally observed to have moderate infestation (45.0%). More plants with larval frass were found at the early-whorl stage (82.5%) than at the late-whorl stage (71.3%). The percentage of plants with foliar damage at the late-whorl stage (82.5%) was slightly higher than at the earlywhorl stage (81.5%). Damage severity scores on early-whorl plants (1.26) was not significantly different (p>0.05) from latewhorl plants (1.21). Information provided would inform pest management intervention for S. frugiperda.