Correlation of cereal phenolic content with Imidacloprid susceptibility and detoxification enzyme activities of Diuraphis noxia

Russian wheat aphid, Diuraphis noxia is one of the economic and polyphagous pests of cereals that are exposed to various chemicals such as phenols. In this research, to investigate the possible effect of host phenolic content on the effectiveness of chemical control, Imidacloprid susceptibility was detected for aphids reared on wheat (Shiroodi and Gascogne) and triticale (Sanabad and Juanillo 92) cultivars, under greenhouse bioassay. The LC50 values of Imidacloprid against the mentioned populations were 2.41, 3.56, 4.89, and 5.73 mg a.i. L-1, respectively. Therefore, the highest Imidacloprid susceptibility belonged to the Shiroodi population. Based on biochemical studies, the activity of alpha and beta esterases, glutathione S transferases, and cytochrome P450 for the Gascogne population was 1.32, 1.16, 1.16, and 1.5 times that of the Shiroodi population, respectively. These ratios were 1.82, 1.96, 1.4, and 2 for the Sanabad population and 2.09, 2.48, 1.51, and 2.25 for the Juanillo 92 population, respectively. Moreover, the phenol content of the mentioned cultivars was 2.19, 2.71, 3.48, and 3.87 mg per gram of leaf, respectively. The data analysis showed a positive and significant correlation between the cereals' phenolic content with the research subjects. Considering the biochemical relationships between D. noxia and its host plants, the value of plant phenolics can be suggested as a suitable index for the prediction of aphid response to Imidacloprid.