Levels, inheritance and stability of resistance to Bacillus thuringiensis formulation in a field population of the diamondback moth, Plutella xylostella (Lepidoptera: Plutellidae) from Thailand

Abstract

We investigated levels, genetic traits and stability of resistance to Bacillus thuringiensis in the Bang Bua Thong (BS) colony of the diamondback moth, Plutella xylostella, collected in Thailand. The BS colony exhibited 668 and 66.5-fold resistance to formulations derived from B. thuringiensis subsp. kurstaki (ToarowCT^[○!R] and B. thuringiensis subsp. aizawai (XenTari^[○!R], respectively. In order to determine the genetic traits of resistance, two reciprocal crosses and their offspring were checked for sensitivity to B. thuringiensis using the laboratory susceptible (H) and the resistant BS colonies. Analysis of the dose-mortality relationship of their progeny suggested that resistance to B. thuringiensis in the BS colony might be polyfactorial. Susceptibility to B. thuringiensis (ToarowCT^[○!R] and XenTari^[○!R] in the BS colony was not quickly restored in the absence of B. thuringiensis selection.