Eco-friendly management of Spodoptera litura (Lepidoptera: Noctuidae) in tomato under polyhouse and field conditions using Heterorhabditis bacteriophora Poinar, their associated bacteria (Photorhabdus luminescens), and Bacillus thuringiensis var. kurstaki

Abstract

Abstract Background Insect pests cause substantial agriculture losses annually, and their regulation through chemical pesticides instigates a prolonged detrimental impact on the environment and human health. The upsurge in difficulties such as pesticide residue, soil degradation and pest resistance acted as the pacesetter for research on biological control with a prime focus on entomopathogens. To aid in knowing the biocontrol potential of these creatures, the present work deals with the applications of entomopathogenic nematode Heterorhabditis bacteriophora EUPT-SD, and entomopathogenic bacteria (EPBs) Photorhabdus luminescens and Bacillus thuringiensis var. kurstaki against the 4th larval instar of Spodoptera litura (Fabricius) (Lepidoptera: Noctuidae) in the laboratory experiment, polyhouse as well as field condition. Results The results demonstrated that EPB, P. luminescens, caused the highest 100% larval mortality at the highest concentration of 5 × 102 CFU/ml after 96 h of infection, followed by B. thuringiensis var. kurstaki which resulted in 98% at a concentration of 5 × 102 CFU/ml and 92% mortality at the treatment with H. bacteriophora EUPT-SD (140IJs/ml) under laboratory bioassay study. In the polyhouse and field evaluation tests, again the P. luminescens was recorded as the most effective, followed by B. thuringiensis and H. bacteriophora, respectively. It was found that the treated plots experienced lesser damage when compared to non-treated plots. Conclusion Applications of these pathogens are nature friendly and are a proficient alternative to synthetic chemical insecticides. It is suggested from the present investigation that the use of P. luminescens was the best biocontrol agent to overcome the local pest problems of this region because it is safe for animals, humans, non-target insect pests, plants, as well as for the environment.