Mortality factors of Cnaphalocrocis medinalis Guenee (Lepidoptera: Crambidae) in bio-intensive pest management modules of rice

Abstract

Rice pests viz., stem borer and leaf folder are major biotic constraints for rice production. Bio-intensive pest management (BIPM) is the way forward to reduce the pesticide usage and conservation of beneficial insect biodiversity which in turn enhances the natural control. In order to assess the impact of BIPM practices on the incidence of pests and their natural control, the present study was conducted during kharif- 2020. The BIPM practices included, application of farm yard manure; rice husk ash; wet seed treatment with Pseudomonas fluorescens, Trichoderma harzianum IIRR strain and Bacillus subtilis IIRR strain; clipping of seedlings; alley ways and foliar application of bio-agents. Fortnightly observations were taken by visual counts. The natural enemies count per quadrat of braconids (8.50-9.50), dryinids (5.25-6.25), ichneumonids (1.00-1.25), predatory ants (3.50-5.50), carabids (2.00-4.50), dragonflies (1.00-1.75), damselflies (2.00-2.75), tettigonids (1.00), tetragnathids (28-42) and lycosids (35.00-36.50) was significantly higher in BIPM treatments and least in farmer’s practice plots. The diseased leaf folder larvae were highest in untreated control (9.50 per quadrat), followed by BIPM 1 (7.25 per quadrat) and least in farmer’s practice 2 (2.50 per quadrat). BIPM 3 recorded highest yield of 8475 Kg/ ha, followed by BIPM 1 (8275 Kg/ ha), farmer’s practice 1 (7825 Kg/ ha), BIPM 2 (7750 kg/ ha), untreated control (7250 Kg/ ha) and farmer’s practice 2 (7050 Kg/ ha). BIPM practices had a good impact on improving the yields and enhancing the mortality rate of leaf folder through improving predator, parasitoid and entomopathogenic fungi densities.