Mode of inheritance of Indoxacarb resistance in diamondback moth, Plutella xylostella (L.) and cross resistance to different groups of pesticides

The development of insecticidal resistance in diamondback moth (DBM) Plutella xylostella has immediate implications for its management. In this study, we examined the mode of inheritance of Indoxacarb resistance in P. xylostella. The indoxacarb-resistant strain (Px-R) was obtained through continuous laboratory selection with increasing doses of indoxacarb in each generation. At the 14th generation of selection, the resistance ratio of Px-R strains was 238 over the susceptible strain (Px-S). The mode of inheritance to Indoxacarb in P. xylostella was examined performing standard reciprocal crosses between Px-R and Px-S and response of Px-R, Px-S and F1 hybrid progenies to Indoxacarb through leaf dip bioassay. The degree of dominance (D) and heritability (h) of F1 hybrid progeny ranged from -0.001 to 0.0012 and 0.499 to 0.506, respectively. The Indoxacarb resistance was appeared to be autosomal and inherited as a semi-dominant trait. The Px-R strain of P. xylostella showed little cross resistance to cypermethrin and there was no cross resistance to other pesticides viz., chlorpyrifos, spinosad, karanjin, xentari (Bta-Cry1C) and MVP-II (Cry1Ac). Since the Indoxacarb resistance inherited as a semi-dominant trait in P. xylostella, the sub lethal doses and frequent use of indoxacarb should be avoided for the management of P. xylostella. Moreover, Px-R of P. xylostella showed positive cross resistance to synthetic pyrethroids (cypemethrin), therefore indoxacarb and synthetic pyrethroids should not be recommended together for management of P. xylostella.