Kerentanan Plutella xylostella dari Garut, Jawa Barat, terhadap Lima Jenis Insektisida Komersial dan Ekstrak Tephrosia vogelii

Abstract

Plutella xylostella is a major pest of cabbage worldwide which can reduce cabbage yield significantly. Farmers often use insecticides to control the pest, but intensive insecticide use can lead to the development of pest resistance to insecticides. This study was conducted to determine the susceptibility of P. xylostella from Garut, West Java, to five commercial insecticides, i.e. chloranthraniliprole, deltamethrin, emamectin benzoat, profenofos, and spinetoram, as well as to Tephrosia vogelii extract. The commercial formulations of those five insecticides and ethyl acetate T. vogelii leaf extract were tested against second instar larvae P. xylostella with a leaf-dip feeding method in which the feeding treatment was given for 48 hours. The number of dead larvae was counted daily until 96 hours after treatment (HAP), then larval mortality data were analyzed by the probit method. Based on LC95 at 96 JSP, deltamethrin and profenofos had low toxicity on P. xylostella larvae, while chloranthraniliprole was moderately toxic. LC95 of these insecticides were 3677.09, 10872.00, and 362.36 mg a.i./l, respectively, which were 367.7, 14.5, and 9.2-fold higher than their respective recommended field rates. On the other hand, P. xylostella larvae were still susceptible to emamectin benzoat, spinetoram, and T. vogelii extract. LC95 of emamectin benzoate and spinetoram were 9.28 and 3.63 mg a.i./l, respectively, which were 1.1 and 3.3-fold lower that their respective recommended field rate. Meanwhile, LC95 of T. vogelii extract was 2907 mg/l which was lower than that of deltamethrin and profenofos. In addition to lethal effect, emamectin benzoate and spinetoram could inhibit the formation of pupal development, whereas deltamethrin, emamectin benzoate, and profenofos caused in inhibition of adult emergence.