Seasonal difference in fall armyworm Spodoptera frugiperda (Lepidoptera: Noctuidae) abundance and plant injury on selected maize varieties in Ibadan, Southwest Nigeria

Abstract

The fall armyworm, Spodoptera frugiperda J.E Smith, is a highly destructive insect pest of maize that first invaded Africa in 2016 and has since posed additional constraints to maize production and food security in the region. This study thus investigated the seasonal difference in the abundance of S. frugiperda egg masses and larvae on 25 maize varieties during the early and late planting seasons of 2018 and 2019 in Ibadan, southwest Nigeria. The relationship between larva abundance and foliar damage was also investigated at three-, five- and seven weeks after planting (3WAP, 5WAP, and 7WAP). Results showed that abundance was higher in 2018, in the early season, and at 3WAP. Though foliar damage occurred weekly in both seasons, the relationship between foliar damage severity and larva abundance at 7WAP was consistently weak and insignificant. Also, in both seasons, most of the observed kernel damage was caused by stem borer and not fall armyworm larvae. To make timely fall armyworm management decisions, regular field scouting, especially within the first three weeks after planting, is recommended.