Field evaluation of whorl application of sand mixed entomopathogenic nematodes for the management of invasive fall armyworm, Spodoptera frugiperda (J. E. Smith) (Lepidoptera: Noctuidae) in sweet corn

Abstract

Abstract Background Fall armyworm (FAW) Spodoptera frugiperda, also called ‘whorlworm’ is a global pest threatening maize production. Larvae stay in the whorl of maize/sweet corn and efficient delivery of insecticides or bio-agents is the major issue for its successful management. Biological control of FAW through entomopathogenic nematodes (EPNs) offers promise, as EPNs are soil colonizers and commercially available in various formulations, soil or sand can ideally be exploited as natural substrate targeting FAW under field conditions. Results In the present study, field evaluations were carried out using the aqueous suspension of Steinernema carpocapsae and Heterorhabditis indica in two cropping seasons. The Infective Juveniles (IJs) stages of EPNs mixed with sand at different doses were applied to the whorl region of sweet corn twice during cropping season, i.e. on 25th and 40th day after sowing. For comparison, a recommended insecticide, Chlorantraniliprole 18.5 SC mixed in sand was taken as check. S. carpocapsae @ 500 IJs, significantly reduced the larval population and leaf damage score. It was statistically on par with Chlorantraniliprole 18.5 SC whorl application. Principal component analysis revealed that there was a relationship between larval population and leaf damage score. Survival of S. carpocapsae was significantly greater than the H. indica in the three media tested. Soil was found to be the best media followed by sand and frass. Conclusions Field study of whorl application of sand mixed EPNs supported by laboratory studies on the persistence connoted that EPNs could be used as an eco-friendly option through whorl application for the management of FAW.

Keywords

• Spodoptera frugiperda
• Entomopathogenic nematodes
• Whorl application
• Persistence
• Biological control
• Aqueous suspension