Background: Entomopathogens such as nematodes, bacteria and fungi are well recognized for their biocontrol potential. This study was carried out to examine the insecticidal properties of the Heterorhabditis bacteriophora Poinar, Beauveria bassiana Balsamo-Crivelli, Bacillus thuringiensis Berliner, individually and in combination against 3rd instar larvae of Spodoptera litura Fabricius (Noctuidae: Lepidoptera) under controlled laboratory and greenhouse conditions at Eternal University, Baru Sahib, Sirmaur, Himachal Pradesh. Results: The results demonstrated that the combined applications of the tested entomopathogens resulted in 100% insect mortality under the laboratory conditions. Among the individual concentrations, applications of 200 IJs/ml were noticed highly virulent with (98%) mortality, followed by B. thuringiensis (96%) and then by B. bassiana (92%). However, single treatments were also evaluated that further showed a highest mortality in the target pest by H. bacteriophora, followed by B. thuringiensis. Among the combined treatments by H. bacteriophora plus B. thuringiensis (200 IJs + 1 × 10¹² CFU/cm²) more effective caused (100%) mortality were noticed in the laboratory and (28%) under the greenhouse conditions than H. bacteriophora plus B. bassiana (200 IJs + 1 × 10¹⁰ conidia/cm²) that caused (100%) mortality and (34%) damage under both, laboratory and greenhouse conditions. Conclusion: Laboratory bioassay and greenhouse evaluation tests demonstrated that the combined sprayed treatments showed reliable and fast synergism. This study could be recommended to the farmers to control the pest.

The cabbage butterfly, Pieris brassicae Linnaeus (Lepidoptera: Pieridae), is an oligophagous and invasive insect pest of various economically important cole crops. Recently, there have been reports about an increase in the incidence and damaging activities of cabbage butterflies, signifying that the existing control methods fail to meet the grower’s expectations. Entomopathogenic nematodes (EPNs) and their endosymbiotic bacteria have immense potential for the control of a wide range of insect pests. In this investigation, the EPN species Steinernema carpocapsae and its associated bacterial species, Xenorhabdus nematophila, were isolated and identified through morphological and molecular techniques. The laboratory bioassay experiment was performed using S. carpocapsae and X. nematophila against the 3rd instar larvae of P. brassicae (25 ± 1 °C; RH = 60%). The efficacy of EPN suspension (30, 60, 90, 120, 150 IJs/mL) and bacterial suspension (1 × 10⁴, 2 × 10⁴, 3 × 10⁴, 4 × 10⁴, and 5 × 10⁴ CFU/mL) via contact and oral routes showed significant mortality among the larvae. Surprisingly, 100% insect mortality within 48 h was recorded in the bacterial inoculum 5 × 10⁴ CFU/mL. However, in the case of EPNs (S. carpocapsae), 150 IJs/mL caused the highest, 92%, larval mortality rate after 96 h. The results signify that both indigenous EPNs and their associated bacteria can provide efficient control against P. brassicae larvae and could effectively contribute to IPM programs. However, further analyses are required to authenticate their effectiveness in field conditions.

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.

Background: Cabbage butterfly, Pieris brassicae Linnaeus (Lepidoptera: Pieridae), is a major insect pest affecting cole crops worldwide. Excessive applications of chemical-based insecticides have a devastating impression over the organisms and environment. Results: In this study, entomopathogenic nematode (EPN) Heterorhabditis bacteriophora Poinar strain EUPT-S26 (local isolate) was evaluated for Pieris brassicae control under polyhouse and field conditions. Under the polyhouse conditions, the highest insect mortality 91.6 and 94.0% was observed in the plots treated with the nematodes suspension 1500 IJs/ml and 2000 IJs/ml, respectively. Based on the highest cabbage plant protection under polyhouse conditions, H. bacteriophora EUPT-S26 was also applied for field assays in the course of the crop’s productive phase. Data demonstrated from the field treatments signify the highest concentration (2000 IJs/ml) showed the maximum larval mortality and least damage percentage 45 ± 1.07% that remained constant until harvesting; this resulted in the highest productivity in polyhouse and under field conditions. Conclusion: According to assessed field conditions, it was suggested to perform 3 applications of EPNs during the vegetative phase and at the time of head formation to increase productivity and to reduce damage. The results approved that EPNs are an effective alternative of chemical-based insecticides to control the cabbage butterfly.