RNA interference of Dicer-1 and Argonaute-1 increasing the sensitivity of Aphis gossypii Glover (Hemiptera: Aphididae) to plant allelochemical.

Plant allelochemicals are a group of important defensive agents of plants, which have been documented to be deleterious to insect herbivores. In the present study, we found that the expression level of Dicer-1 was significantly increased when Aphis gossypii adults fed on plant allelochemicals (tannic acid and gossypol) incorporated artificial diets. Consider that miRNAs play great regulatory roles in various biological processes, this suggested that miRNAs may be related to the regulation of enzymes involved in metabolism of plant allelochemicals in A. gossypii. To further reveal the roles of miRNAs in the response of A. gossypii against plant allelochemicals, both Dicer-1 and Argonaute-1, an important component of the RNA-induced silencing complex (RISC) in miRNA pathway, were silenced using systemic RNA interference (RNAi). The results indicated that silence of Dicer-1 reduced the expression of miRNAs, and resulted in a high mortality of A. gossypii when fed on both tannic acid and gossypol. The silencing of Argonaute-1 resulted in the mortality of A. gossypii by the treatment of tannic acid significantly increased compared with control, however, the sensitivity of A. gossypii to gossypol was not significantly changed. It suggested that miRNAs play potential regulatory roles in the response of A. gossypii to plant allelochemicals. These results should be useful to understand the molecular mechanisms of the cotton aphid adaption to plant allelochemicals.