Decreased susceptibilities of four field populations of the diamondback moth, Plutella xylostella (L.) (Lepidoptera: Yponomeutidae), to acetamiprid

Abstract

The efficacy of acetamiprid, a neonicotinoid insecticide, against four field populations of the diamondback moth, Plutella xylostella (L.), from Aichi, Hyogo and Kagoshima Prefectures in Japan was determined using the leaf-dipping method. The data obtained indicated that, compared to the reference Osaka susceptible strain (OSS), the four field populations were tolerant to the insecticidal effect of acetamiprid, displaying LC₅₀ resistance ratio (RR) of 4.5-9.0 Maintaining the population from Aichi Prefecture in the laboratory without exposure to acetamiprid resulted in a decline of the LC₅₀ RR from 9.0 to 1.6 over seven generations, suggesting that acetamiprid-resistance is not stable.