Bio-Ecology of Fall Armyworm, Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae) in Sugarcane

Abstract

Fall armyworm (FAW) Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae) has become a sporadic pest of sugarcane. Since, it is a relatively new pest of sugarcane with the first report of occurrence came in 2018, detailed reports on its biology, ecology and management are lacking in the public domain. The present study reports the biology, ecology and molecular taxonomy of FAW population occurring in sugarcane. FAW in sugarcane passed through six larval instars to attain its pupal stage. The head capsule widths of first through fifth instar larvae of FAW were in the range of 0.260–0.352, 0.400–0.590, 0.652–0.900, 1.010–1.410 and 1.700–2.162 mm with the mean values of 0.284, 0.470, 0.753, 1.154 and 1.908 mm, respectively. FAW could complete its life cycle in 25.5 (male)—27.2 (female) days in sugarcane (cv. Co 86,032) with mean fecundity of 528 eggs under laboratory condition (27 ± 2 °C). The artificial diet developed and used to rear the FAW in laboratory also supported its growth, development and reproduction. FAW could successfully complete its life cycle in 23.1–25.4 days with the mean fecundity of 347 eggs in the artificial diet. We have also constructed age-specific fecundity tables for both cane-reared and diet-reared populations of FAW. Though the generation time and doubling time were on par with each other, the net reproductive rate, which represents the number of female progenies produced per female per generation was 111.5 for cane-reared population as against 62.3 for diet-reared population indicating the supremacy of the natural host in promoting the reproductive traits of FAW. It was also confirmed through the development of mtCOI gene-based DNA barcodes that the FAW population on sugarcane was “R strain”.