Resistance of Brown Plant Hopper, Nilaparvata Lugens(Stal 1854) to Carbofuran in Different Rice Growing Districts of Sri Lanka

Abstract

Resistance of Brown Plant Hopper (BPH) Nilaparvata lugens to Carbofuran was studied in the laboratory by comparing LC50 values observed for B.P.H . from five rice growing districts o f Sri Lanka. Highest LCs0 value (0.000666 percent a.i. carbofuran) for BPH from Ampara district showed & highly significant development o f resistance compared to four other districts. Highest susceptibility was shown by BPH from Galle, Kandy and Kegalla districts, LC50 values being 0.000340,0.000365,0.000354 percent a.i. carbofuran respectively. BPH from Kurunegala LC50 being 0.000469 percent a.i. carbofuran did not provide any clear-cut indication of development of resistance demanding further investigations.