RESISTANCE EVALUATION IN RHYZOPERTHA DOMINICA (COLEOPTERA; BOSTRICHIDAE) TOWARDS PHOSPHINE AND DELTAMETHRIN UNDER LABORATORY CONDITION

Abstract

The most destructive pest of stored grain commodities is Rhyzopertha dominica (F.), which causes tremendous loss in favorable conditions. During the hot and humid conditions the pest population builds up sharply and deteriorates the quality of stored grains. Mostly, the fumigants and insecticides are used for sustainable management of pest. The residual toxicity of deltamethrin and phosphine gas was evaluated against Rhyzopertha dominica known as the lesser grain borer. The grains commodities were treated with the 6 concentrations of insecticides (0.01, 0.02, 0.03, 0.04, 0.05 and 0.06 ppm) and phosphine (0.006, 0.007, 0.008, 0.009, 0.01 and 0.011 ppm) to test percent mortality of insect pest under laboratory conditions. The percent mortality data of insecticides and phosphine were noted after 24, 48 and 72 hours and 7, 14 and 21 days. The overall study results showed that maximum mortality was 76.65% in susceptible strains while 42.80% in resistant strain against deltamethrin. The maximum mortality at 0.011ppm against phosphine 56.35% and 31.15% was observed in resistant and susceptible populations of Rhyzopertha dominica. The overall data indicated that after 72 hours the lesser grain borer 3.65 times fold resistant against deltamethrin while 0.882 time fold resistance against phosphine after seven days interval over the susceptible strains.