HcCYP6AE178 plays a crucial role in facilitating Hyphantria cunea's adaptation to a diverse range of host plants.

Strong multi-host adaptability significantly contributes to the rapid dissemination of Hyphantria cunea. The present study explores the involvement of cytochrome P450 monooxygenase (P450) in the multi-host adaptation of H. cunea and aims to develop RNA pesticides targeting essential P450 genes to disrupt this adaptability. The results showed that inhibiting P450 activity notably reduced larval weight and food-intake across seven plants groups. The P450 gene HcCYP6AE178 was highly upregulated in H. cunea larvae from medium- and low-preference host plant groups. Silencing HcCYP6AE178 significantly decreased H. cunea larval body weight, increased larval mortality, inhibited energy metabolism genes expression and interfered with growth regulatory genes expression. Overexpression of HcCYP6AE178 enhanced the tolerance of Drosophila and Sf9 cells to the plant defensive substances cytisine and coumarin. The RNA pesticide CS-dsHcCYP6AE178 constructed using chitosan (CS) exhibited remarkable stability. Treatment with CS-dsHcCYP6AE178 effectively reduced H. cunea larval body weight, heightened larval mortality, and disrupted growth regulatory genes expression in low-preference host plant groups. Combined treatment of CS-dsHcCYP6AE178 and coumarin significantly elevated H. cunea larval mortality compared to coumarin alone, accompanied by the inhibition of growth regulatory genes expression and an abnormal increase in energy metabolism genes expression. Taken together, HcCYP6AE178 is essential for the adaptation of H. cunea to multiple host plants, and RNA pesticides targeting HcCYP6AE178 can effectively impair the performance of H. cunea in different host plants.