Effect of Selected Maize (Zea mays L.) Genotypes on the Biology of the Fall Armyworm (Spodoptera Frugiperda JE Smith) Under Controlled Environment
TL;DR
The inverse relationship between larval weight and development duration highlights the role of maize genotype in influencing FAW growth dynamics, with resistant varieties prolonging development and suppressing larval biomass accumulation.
Abstract
Maize (Zea mays L) has lost its natural defence mechanisms against herbivorous pests due to domestication and artificial selection that focused on productivity rather than pest resistance. The fall armyworm (FAW) has become an invasive pest of maize and other crops in Africa. The objective of this study was to determine the effect of maize genotypes, SC DUMA43, SC SUNGURA301, HARAKA WH101, Yellow landrace, Red landrace and FAWTH2003 on FAW feeding and development. The experiment was set in a laboratory in a no-choice bioassay in a Complete Randomised Design (CRD) replicated three times. Data was collected on the leaf weight after feeding, leaf damage score, larval mortality, average larvae weight, instar progression, larval period, pupation duration, average pupal weight, adult sex ratio and total lifecycle. Data was tested for normality and subjected to analysis of variance (ANOVA) using SAS v. 9.3.0. Genotype SC Sungura 301 and Haraka WH 101 were more preferred by FAW with leaf portion losses of 2.83g and 2.86g respectively, compared to FAWTH2003 with leaf portion loss of 2.02g. Maize genotypes had a significant (p ≤ 0.001) effect on larval weight, mortality and development time. FAWTH2003 had the highest mortality of the larvae at p ≤ 0.0001 significance. The larvae that fed on HARAKA WH101 had the heaviest larval weight (0.15 g) with the shortest larval duration (16.33 ± 0.88 days), suggesting superior nutritional quality and high susceptibility to infestation. In contrast, those larvae that fed on the FAWTH2003 genotype had the lightest larval weight (0.10g) and the longest duration (19.67±1.20 days), suggesting cases of antibiosis and possible antixenosis effects that reduced growth and delayed development. The inverse relationship between larval weight and development duration highlights the role of maize genotype in influencing FAW growth dynamics, with resistant varieties prolonging development and suppressing larval biomass accumulation. Integrating host plant resistance (HPR) in FAW management is necessary as an Integrated Pest Management (IPM) strategy.