Inhibiting essential elements of the DNA methylation pathway negatively impacts the miRNA pathway and fitness of the whitefly Bemisia tabaci

DNA methylation is an epigenetic process that involves the chemical modification of DNA, leading to the regulation of its transcriptional activity. It is primarily known for the addition of methyl groups to cytosine in DNA. The whitefly Bemisia tabaci is a polyphagous pest insect and a vector that is responsible for transmitting numerous plant viruses, resulting in significant economic losses in agricultural crops globally. In our study, we characterized the expression of two key DNA methylation genes, the DNA methyltransferases Dnmt1 and Dnmt3, in B. tabaci. Additionally, we explored the impact of inhibiting DNMTs on the miRNA pathway and fitness of whitefly. To investigate the role of the DNA methylation pathway in B. tabaci, we found that the expression of Dnmt1 and Dnmt3 varied across different tissues and developmental stages of B. tabaci. We employed azacytidine (5-AZA) treatment of adults to inhibit DNMTs (DNMT1 and DNMT3). Administration of 5-AZA affected the survival and reproduction of this pest. Moreover, inhibition of DNMTs led to a decrease in the expression of the miRNA pathway core genes Dicer1 and Argonaute1, which subsequently resulted in reduced expression of Let-7 and miR-184 which are essential microRNAs in the physiology and biology of insects. The study suggests that DNA methyltransferases could be targeted for developing an inhibition strategy to control this pest and vector insect.