Zachary Y. Huang, Guowu Bian, Zhiyong Xi, Xianbing Xie

The Varroa mite, (Varroa destructor), is the worst threat to honey bee health worldwide. To explore the possibility of using RNAi to control this pest, we determined the effects of knocking down various genes on Varroa mite survival and reproduction. Double-stranded RNA (dsRNA) of six candidate genes (Da, Pros26S, RpL8, RpL11, RpP0 and RpS13) were synthesized and each injected into Varroa mites, then mite survival and reproduction were assessed. Injection of dsRNA for Da (Daughterless) and Pros26S (Proteasome 26S subunit ATPase) caused a significant reduction in mite survival, with 3.57% ± 1.94% and 30.03% ± 11.43% mites surviving at 72 h post injection (hpi), respectively. Control mites injected with GFP-dsRNA showed survival rates of 81.95% ± 5.03% and 82.36 ± 2.81%, respectively. Injections of dsRNA for four other genes (RpL8, RpL11, RpP0 and RpS13) did not affect survival significantly, enabling us to assess their effect on Varroa mite reproduction. The number of female offspring per mite was significantly reduced for mites injected with dsRNA of each of these 4 genes compared to their GFP dsRNA control. Knockdown of the target genes was verified by real time PCR for two genes important for reproduction (RpL8, RpL11) and one gene important for survival (Pros26S). In conclusion, through RNA interference, we have discovered two genes important for mite survival and four genes important for mite reproduction. These genes could be explored as possible targets for the control of Varroa destructor in the future. This article is protected by copyright. All rights reserved.