Knockout of the ABCB1 Gene Increases Susceptibility to Emamectin Benzoate, Beta-Cypermethrin and Chlorantraniliprole in Spodoptera frugiperda

SIMPLE SUMMARY: Spodoptera frugiperda is an invasive lepidopteran pest that causes extensive damage to many commercial crops. To control this pest, the use of chemical pesticides has become increasingly important because of their high efficiency, low cost and ease of mechanized operations. However, despite the proven effectiveness of pesticides, the long-term use of chemicals not only pollutes the environment, but also leads to resistance in field populations, making pest control more difficult. In this study, we used the CRISPR/Cas9 system to generate an ABCB1 knockout strain to explore its potential role in determining susceptibility to chemical pesticides or Bt toxins. We compared the mortality of WT strains and knockout strains treated with 10 insecticides and three Bt proteins, and found that the insects were significantly more susceptible to the three insecticides (emamectin benzoate, beta-cypermethrin and chlorantraniliprole) after ABCB1 was knocked out. Our results showed that ABCB1 is closely related to the detoxification metabolism of some pesticides, and suggest that the resistance of Spodoptera frugiperda to emamectin benzoate, beta-cypermethrin and chlorantraniliprole may be related to the overexpression of ABCB1. This lays a foundation for a follow-up study on the resistance mechanism of Spodoptera frugiperda. ABSTRACT: ATP-binding cassette transporter B1 (ABCB1, or P-glycoprotein) is known to be an important participant in multidrug resistance in mammals, and it also has been proved as a transporter for some insecticides in several lepidopteran insects, yet the precise function of this transporter in Spodoptera frugiperda is unknown. Here, we generated a SfABCB1 knockout strain of the S. frugiperda using the CRISPR/Cas9 system to explore its potential roles in determining susceptibility to chemical insecticides or Bt toxins. Bioassay results showed that the susceptibility of SfABCB1 knockout strain to beta-cypermethrin, chlorantraniliprole and emamectin benzoate were significantly increased compared with the wild-type strain DH19, whereas there were no changes to Bt toxins for Cry1Ab, Cry1Fa and Vip3Aa. Our results revealed that SfABCB1 plays important roles in the susceptibility of S. frugiperda to beta-cypermethrin, chlorantraniliprole and emamectin benzoate, and imply that overexpression of ABCB1 may contribute to beta-cypermethrin, chlorantraniliprole and emamectin benzoate resistance in S. frugiperda.