The larval stage of Spodoptera litura Fab. is more prone to parasitism. Larval parasitoids such as braconids belongs to family Braconidae of order Hymenoptera acts as Ecto parasitoids. Braconids have wide host range and successful biocontrol agent recommended for the control of lepidopteran larvae in many crops and stored grains. The present study on parasitization of braconids on S. litura was conducted under laboratory conditions. The larva of S. litura collected from castor crop from various locations near by Nagpur, Maharashtra, India and reared on castor leaves under laboratory conditions. The larvae were parasitized by two parasitoids namely, Cotesia spp. and Bracon spp. The study revealed that the field collected larva of S. litura when reared on castor leaves showed an average parasitization of 11% and 4.3% by Cotesia spp. and Bracon spp. respectively.

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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