Entomopathogenic nematodes (EPNs) have been identified as promising biocontrol agents for controlling economically important insect pests of agricultural and horticultural crops. The compatibility of entomopathogenic nematode Heterorhabditis indica with 7 CIB registered insecticides was investigated under laboratory conditions. The effect of these insecticides on nematode survival at recommended concentrations was observed after 12, 24, 48, 72 hours upon direct exposure. EPN H. indica was compatible with Imidacloprid 17.8% SL as maximum per cent of live H. indica were observed after 72 h of exposure to this insecticide. Similarly, H. indica was compatible with Fipronil 5% SC up to 48 h of exposure whereas, less than 70% live EPN were there in Thiamethoxam 25% WG, Diafenthiuron 50% WP and Cypermethrin 25% EC resulting these insecticides to be least compatible.  Emamectin benzoate 5% SG and chlorpyriphos 20% EC were incompatible with H. indica after 48 h of exposure. The result of this experiment will help in reducing the dependence on chemical insecticides and thus slowing down the development of insecticide resistance and preventing adverse effects on public health and the environment.

The present study on pathogenicity of entomopathogenic nematodes against Spodoptera litura in laboratory conditions was undertaken during 2020-21, with the aim to ascertain the effectiveness of entomopathogenic nematodes, against an obnoxious cosmopolitan pest S. litura. Experiments were conducted by using entomopathogenic nematode (EPN) isolate Heterorhabditis indica (CICR-Guava), on filter paper, against Galleria mellonella and S. litura at the treatment dose of 10, 20, 30, 40, 60, 80 and 100 IJs/100µl along with control (Sterile distilled water). The results of our study revealed that, EPN isolate H. indica (CICR-Guava) caused 100% mortality at the treatment dose of 40 IJs/100µl within 72 h of infection in 5th instar larvae of G. mellonella and in case of S. litura, 100% mortality was recorded within 72 h of infection at the treatment dose of 100 IJs/100µl in 3rd instar larvae, which was found more susceptible. The median lethal concentration of H. indica (CICR-Guava) for 5th instar larvae was 2.29 IJs/100µl. The result of reproductive potential of isolates of entomopathogenic nematodes revealed that the highest yield was obtained from 5th instar larvae of G. mellonella at treatment dose of 100 IJs/100µl 278667 IJs per larva. In case of S. litura, the highest yield obtained was 152533 IJs. It could be concluded that, there was a positive correlation between nematode treatment concentration, time of exposure and the insect mortality of the tobacco cut worm and multiplication rate of IJs increased with increase of exposure time and size of larvae. This EPN isolate, H. indica (CICR-Guava) can be suggested as biocontrol agents for the control of S. litura in the Vidarbha region.

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Rice leaffolder, Cnaphalocrocis medinalis, Guenee is a serious pest of rice and causes significant yield losses. Insecticides are commonly employed to control this pest, but their use often escalates production costs and fosters pesticide resistance. Identifying insect-resistant rice genotypes and their resistance mechanisms is crucial for successful pest management. New sources of resistance providing long-lasting protection against leaffolder can be identified by studying the morphobiochemical characteristics of different rice genotypes. This study explored the role of various morphological traits of certain genotypes that confer resistance. Different biochemical constituents like soluble protein, phenol, total soluble sugar and enzymes viz., peroxidase, polyphenol oxidase and catalase were assessed spectrophotometrically in all infested and uninfested genotypes along with standard resistant (TKM6) and susceptible (TN1) checks. Leaffolder damage was negatively significant with plant height and leaf length (r = -0.903 and − 0.862, P < 0.001 respectively) while leaf width association was significantly positive (r = 0.773, P < 0.001). Among the different plant metabolites analyzed, total soluble sugar and soluble protein showed significant positive correlation (r = 0.778 and 0.788, P < 0.001 respectively) with leaffolder damage, conversely phenol (r = -0.651, P < 0.001) and antioxidative enzymes showed significant negative correlation. When rice genotypes were exposed to leaffolder larval feeding, they exhibited defence responses characterized by reduction in the level of sugars and proteins, accumulation of phenolic compounds and upregulation of antioxidative enzymes. This study emphasized the significance of morphobiochemical characteristics in rice resistance mechanisms against leaffolder. By leveraging these traits, new resistant rice germplasms against leaffolder can be developed.