FIELD ASSESSMENT OF THE LARVAL ABUNDANCE OF FALL ARMYWORM

ABSTRACT

Maize (Zea mays L.) is the most important staple food crop in Africa and is predominantly grown by smallholder farmers. However, the production of this crop is threatened by the invasion and widespread infestation of the fall armyworm (FAW). Spodopterafrugiperda (J. E. Smith). This study was carried out to evaluate the infestations of FAW on late season maize. The specific objectives were to determine the effect of maize variety and Days after Sowing (DAS) on abundance of FAW and to also assess the distribution of FAW larval stages during the maize cropping season. The experiment was carried out from July to October of 2021 at the Experimental Farm of the Department of Crop Science, Faculty of Agriculture, University of Benin, Benin City, Edo State, Nigeria. The experiment was laid out in a split plot design with three replications and two treatments (Variety and DAS). Four varieties of maize were used; two hybrids (Oba 98 and Oba super-6) and two local varieties (white and yellow maize). Data analysis was done using Analysis of variance, Genstat and Least significant test was used for separation of means. From the study, significant differences were observed in means of larvae between the different DAS with 25 DAS having the highest number of larvae (1.903) while there were no significant differences between means of FAW larvae in the four maize varieties, V_l (1.145), V₂ (1.103), V₃ (1.050) and V₄ (1.232). Larval instar stages one, two, three, four, five and six were present from the early whorl (L₁-L₃) to tasselling and silking (V_T) stage though were absent at the maturing stage (R₁-R₃). The distribution of FAW larval stages totally varied with the phenological stages of the maize as they were distributed across all stages. From the result obtained from this study, abundance of FAW was dependent on the DAS but independent of the maize variety grown. Thus, it is therefore important to investigate the infestations of the larval stages of this species with a view to early detection and thus proper timing of control measures as early planting of maize may significantly reduce the infestation by this specie.