Screening of newly isolated indigenous entomopathogenic nematodes against Spodoptera litura Fabricius (Lepidoptera: Noctuidae)

Aim: Insecticides have traditionally been used to control S. litura, although bio-pesticides as alternative control measures are also in demand due to soil residual issues and other environmental dangers. Another safe technique for controlling this important pest is entomopathogenic nematodes (EPNs). Methodology: This study evaluated the infectivity of ten native recently isolated entomopathogenic nematodes against S. litura by assessing their penetration and multiplication in S. litura. The efficiency of the promising EPNs against second, third and fourth instars S. litura larvae was further examined. Results: Among the tested EPNs, Steinernema sp. (IARI-EPN RP 03), Heterorhabditis sp. (IARI-EPN RP 06), and Oscheius sp. (IARI-EPN RP 07) were intensely harmful to S. litura, producing 100 percent mortality in 72 hrs, followed by Steinernema sp. (IARI-EPN RP 09), which caused 92 percent mortality, and Oscheius sp. (IARI-EPN RP 10) was the least pathogenic recording 58 percent mortality. Heterorhabditis sp. (IARI-EPN RP 06) showed the maximum penetration, followed by Oscheius sp. (IARI-EPN RP 07) and Oscheius sp. (IARI-EPN RP 08), with Oscheius sp. (IARI-EPN RP 04) showed the least penetration. The second instar larvae of S. litura were highly vulnerable to EPNs, followed by third and fourth instar larvae. According to the findings, Steinernema sp. (IARI-EPN RP 03) and Heterorhabditis sp. (IARI-EPN RP 06) were most virulent against S. litura. Interpretation: As a result, both EPNs have the potential to act as biological control agents for S. litura. Furthermore, the fifth instar S. litura larva were more suited for multiplication, indicating that this insect is suitable for EPN production. Field testing of these promising EPNs will reveal their efficacy in managing S. litura in a sustainable manner. Key words: Bio-pesticides, Entomopathogenic nematodes, Heterorhabditis, Insects, Oscheius, Steinernema