On-farm impact of egg parasitoid, Trichogramma spp. against lepidopteran pests in organic basmati rice

Abstract

On farm impact of Trichogrammatids was studied against lepidopteran pests, i.e., yellow stem borer, Scirpophaga incertulas (Walker) and leaf folder, Cnaphalocrocis medinalis (Guenee) in organic basmati rice (var. Pusa 1121) over an area of 20 and 60 hectares during 2014 and 2015, respectively. Six augmentative releases of Trichogramma chilonis and T. japonicum each @ 1,00,000 parasitoids/ha were made starting from 30 days after transplanting (DAT) and was compared with untreated control. Based on the overall mean, the biocontrol treatment (1.74% DH) was significantly effective in reducing the dead heart incidence as compared to untreated control (4.52% DH). The reduction in dead hearts was 61.50 per cent in biocontrol over untreated control. The mean incidence of white ears was also significantly lower in biocontrol field (2.05%) as against untreated control (4.89%) resulting in a reduction of 58.08 per cent. Similarly, leaf folder damage in biocontrol (2.04% LFDL) resulted in 62.50 per cent reduction over untreated control (5.44% LFDL). Grain yield in biocontrol fields (29.81 q/ha) was 18.76 per cent more than the untreated control (25.10 q/ha). The increase in yield due to control of stem borers and leaf folder in biocontrol fields resulted in an additional benefit of INR 16332/- and INR 9818/- during 2014 and 2015, respectively. Conclusively, 6 releases of T. chilonis and T. japonicum each @ 1,00,000/ha resulted in lower incidence of rice insect pests and higher grain yield in organic basmati rice with an additional benefit over untreated control.