Field resistance of Plutella xylostella (Lepidoptera: Plutellidae) to lufenuron: Inheritance and lack of cross-resistance to methoxyfenozide

Plutella xylostella (L.), commonly known as diamondback moth, is one of the most important pests of Brassicaceae in Brazil. This study aimed to assess the susceptibility of P. xylostella and pattern of resistance inheritance to lufenuron, an insect growth regulator (IGR) that impairs the insect molting, as well as the cross-resistance to methoxyfenozide (Nonsteroidal ecdysone agonist). Concentration-mortality bioassays were performed using the leaf dipping method towards field collected populations and genotypes used in the genetic crossings. Populations of this pest, from the mesoregion of Pernambuco (Brazil), were highly resistant to lufenuron. The recommended concentration of lufenumn caused more than 80% mortality of larvae of two populations [Piedade (PDD) and Recife (REC-S)]. Methoxyfenozide caused more than 80% mortality of larvae of all assessed populations, suggesting no cross-resistance between insect growth regulators. The population of Bezerros (BZR-R) was the most resistant (11,283-fold) to lufenumn compared with REC-S population (standard reference). Resistance to lufenuron was inherited as autosomal, incompletely recessive, and monofactorial trait, suggesting that a single gene or a set of genes tightly linked is involved in resistance. Methoxyfenozide is an alternative molecule suggested for the control of P. xylostella in areas where resistance to lufenumn has evolved. Furthermore, information provided in this work should fine-tune insecticide resistance management (IRM) programs to delay the evolution of resistance to chitin synthesis inhibitors like lufenuron, where resistance frequency is incipient.