Genes important for survival or reproduction in Varroa destructor identified by RNAi

The Varroa mite,(Varroa destructor),is the worst threat to honey bee health worldwide.To explore the possibility of using RNA interference 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,RpPO 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 (Gene for proteasome 26S subunit adenosine triphosphatase)caused a significant reduction in mite survival,with 3.57%±1.94% and 30.03%±11.43% mites surviving at 72 h post-inj ection (hpi),respectively.Control mites injected with green fluorescent protein (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,RpPO 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 four genes compared to their GFP-dsRNA controls.Knockdown of the target genes was verified by real-time polymerase chain reaction 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.

Mblk-1 regulates sugar responsiveness in honey bee(Apis mellifera)foragers

Brain transcriptional regulatory network for behavior demonstrates that brain gene expression in the honey bee can be accurately predicted from the expression transcription factors(TFs),but roles for specific TFs are less understood.Mushroom bodies(MBs)are important for learning,memory and sensory integration in the honey bee brain.A TFs,Mblk-1,expressed preferentially in the large-type Kenyon cells of the honeybee MBs is predicted to be involved in brain function by regulating transcription of its target genes in honey bee.However,its function and the mechanism of regulation in behavior of honey bee is still obscure.Here we show that Mblk-1 had significantly higher expression in the brains of forager bees relative to nurse bees.Mblk-1 was significantly inhibited in bees fed small interfering RNA.In addition,inhibition of Mblk-1 decreased sucrose responsiveness in foragers.Finally,we determined that Mblk-1 regulated the messenger RNA of AmGRl.These findings suggest that Mblk-1 may target AmGRl to regulate the sucrose responsiveness of foragers.