Effect of eco-friendly insecticides and biopesticides on spider populations in basmati rice

Abstract

A field trial was conducted during Kharif 2022 and 2023 at the Crop Research Centre, Sardar Vallabhbhai Patel University of Agriculture & Technology, Meerut, Uttar Pradesh, to evaluate the effect of green-label insecticides and biopesticides on spider populations, key natural enemies in basmati rice (Oryza sativa L., Pusa Basmati-1509). The experiment was laid out in a Randomized Block Design (RBD) with eight treatments, each replicated thrice: T1 - Neem oil (Azadirachtin 0.03% w/w, 300 ppm) - 3 lit./ha, T2 - Nimbicidine (Azadirachtin 1% w/w, 10000 ppm) - 2.5 lit./ha, T3 - Bacillus thuringiensis var. kurstaki (6000-8000 IU/mg) - 1.5 kg/ha, T4 - Beauveria bassiana (2×10⁹ cfu/g) - 3 lit./ha, T5 - Metarhizium anisopliae WP (4.7×10⁸ cfu/g) - 2.5 kg/ha, T6 - Chlorantraniliprole 18.5% SC - 150 ml/ha, T7 - Flubendiamide 39.35% SC - 75 ml/ha and T8 - Untreated control. Spider populations were recorded from five randomly selected hills per plot one day before and 7, 14 and 21 days after each spray. Pooled data over the two years revealed that the untreated control consistently maintained the highest spider populations, while Bacillus thuringiensis, Nimbicidine and Neem oil supported relatively higher populations (1.27-2.40 spiders/hill). Beauveria bassiana and Metarhizium anisopliae maintained moderate populations (1.12-1.86 spiders/hill), whereas Chlorantraniliprole and Flubendiamide consistently recorded the lowest numbers (0.93-1.46 spiders/hill), indicating their stronger negative impact on non-target predators. The observations suggest that neem-based and microbial insecticides are comparatively safer to spiders, whereas synthetic chemicals reduce their abundance. These results demonstrate that green-label and bio-rational insecticides can be effectively integrated into eco-friendly pest management strategies in basmati rice, conserving natural enemies and maintaining ecological balance.