<i>Dnmt1</i> is required for early embryo development in the haplodiploid insect, <i>Bemisia tabaci</i> (Hemiptera: Aleyrodidae)

The sweetpotato whitefly, Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae), is a major economic pest that is difficult to manage with current strategies. New strategies will depend on better understanding the biology of whiteflies. For example, little is known about factors that affect primary sex ratio and embryological development in the haplodiploid system of B. tabaci, which may provide an entry point into new control strategies. In this study, we show that expression of DNA methyltransferase 1 (Dnmt1) is required for early embryogenesis in B. tabaci. First, we show that reduction of Dnmt1 expression using RNA interference decreased the number of eggs laid and the viability of eggs but did not affect the adult sex ratio. We also identify key developmental stages during embryogenesis, which have been shown to be consistent in both sexes. Embryos produced from dsDnmt1-treated females failed to form a germ rudiment and had smaller sized nuclei, suggesting inhibition of the cell cycle early in development. Although the specific mechanism by which DNMT1 affects embryogenesis remains elusive, that is, whether the effect is methylation dependent or independent, our study provides insights into DNMT1's function based on when and how DNMT1 is needed.