Damage Caused by Lepidopteran Pests on Maize Fields in Yamoussoukro, Central Côte d’Ivoire

Abstract

Various larvae of Lepidoptera cause severe damage to maize crops. The dynamics of these maize larvae pests have been studied during all stages of plant development. The trial was carried out on the Institut National Polytechnique Houphouët-Boigny farm plots in Yamoussoukro (central Cote d’Ivoire). The study aims were to monitor the dynamics, determine the importance (frequency and abundance), and assess the damage of Lepidopteran pests on the maize variety EV8728 SR using a randomized complete block design with four replicates. The variety was sown on 05 September 2020. Insects were characterized with keys following on-site observation and capture of larvae on the plants. Five Lepidopteran species, grouped into three families, were counted on the plots. Spodoptera frugiperda was the most frequent (Occurrence C = 20.9%) and highly abundant (Relative Abundance Ar = 65.79%). The other Lepidoptera species were rare (C < 5%). However, Sesamia calamistis was very abundant (Ar=15.22%), while Eldana saccharina (Ar = 9.44%) and Ostrinia nubilalis (Ar = 5.25%) were abundant. Helicoverpa zea is scarcely abundant (Ar=4.3%). Furthermore, three Lepidoptera species (E. saccharina, O. nubilalis, and H. zea) were as minor pests (Damage Index I < 10%), while S. calamistis was important pest (I < 25%) and S. frugiperda was major pest (I< 75%). The populations of the insects fluctuated during crop development. The mean dried grain yield varied from 2.4±0.42 to 2.61±0.71 t/ha. Populations of S. frugiperda larvae and their damage appeared more important than those of other Lepidoptera. Knowledge of maize lepidopteran larvae is essential for effectively and efficiently controlling these pests and improving the quality and quantity of maize production.