Function Analysis of P450 and GST Genes to Imidacloprid in Aphis craccivora (Koch)

Abstract

<i>Aphis craccivora</i> (Koch) is an economically important pest that affects legumes in worldwide. Chemical control is still the primary efficient method for <i>A. craccivora</i> management. However, the mechanism underlying insecticide resistance in <i>A. craccivora</i> has not been elucidated. A previous study observed that piperonyl butoxide (PBO) and diethyl maleate (DEM) significantly synergized imidacloprid in <i>A. craccivora</i> field populations, indicating that cytochrome P450 (P450) and glutathione S-transferase (GST) genes may play pivotal roles in imidacloprid resistance. In this study, 38 P450 genes and 10 GST genes were identified in <i>A. craccivora</i> through transcriptomic analysis. The expression levels of these P450 and GST genes were measured in susceptible (SUS) strains of <i>A. craccivora</i> under imidacloprid treatment with LC₁₅, LC₅₀, and LC₈₅ doses. The expression levels of <i>CYP18A1</i>, <i>CYP6CY21</i>, <i>CYP6DA1</i>, <i>CYP6DA2</i>, <i>CYP4CJ1</i>, <i>CYP4CJ2</i>, and <i>CYP380C6</i> were up-regulated in the three treatments. Most of these genes belong to CYP3 and CYP4 Clans. In addition, the expression levels of all P450 and GST genes in <i>A. craccivora</i> were also measured in the Juye (JY) and Linqing (LQ) field populations. The expression levels of <i>CYP6DA2</i>, <i>CYP4CJ1</i>, and <i>CYP380C6</i> were up-regulated in the SUS strain after imidacloprid treatment at three doses, and these genes were overexpressed in the JY population. Furthermore, the sensitivity of <i>A. craccivora</i> to imidacloprid was significantly increased after knockdown of <i>CYP380C6</i> and <i>CYP6DA2</i> through RNA interference. These results may help to elucidate the mechanisms underlying of imidacloprid resistance in <i>A. craccivora</i>.