Bio-efficacy of Pymetrozine 50 WG Against Brown Planthopper, Nilaparvata lugens Stal., Safety to Natural Enemies and Residues in Rice Under Field Conditions of Semi-arid Region of India

Pymetrozine Bio-Efficacy Against Brown Planthopper in Rice

Abstract

The brown plant hopper, Nilaparvata lugens Stal, is a significant insect pest that severely damage rice crops in India. Various management strategies have been implemented to control this pest, with insecticides serving as the primary defence mechanism. Therefore, there is a need to identify new molecules that have selective properties, innovative modes of action, low toxicity to non-target organisms, and environmental safety, all aimed at achieving sustainable pest management. In this context, the bio-efficacy of pymetrozine 50 WG against brown plant hopper, Nilaparvata lugens Stal. was assessed under field conditions at CCS Haryana Agricultural University, Regional Research Station, Karnal, over two kharif seasons. Results indicated that the foliar application of pymetrozine 50 WG at a rate of 150 g a.i. per hectare (5–10 hoppers per hill) was the most effective dose for reducing hopper populations. No phytotoxicity was observed in rice crops following the foliar spray of pymetrozine 50 WG. This chemical also showed relative safety towards natural enemies, including spiders, mirid bugs, and coccinellids. The highest grain yields recorded were 36.1 and 38.2 quintals per hectare with the application of pymetrozine 50 WG at 175 g a.i. per hectare during both seasons, which were comparable to the lower dose of 150 g a.i. per hectare (35.2 and 37.3 quintals per hectare). At harvest, the residues of pymetrozine 50 WG at the recommended dose (150 g a.i. per hectare) and double that rate (300 g a.i. per hectare) were found to be below detectable levels in the soil, rice straw, and grain.