Bacterially expressed dsRNA induces Varroa destructor gene knockdown by honey beemediated oral administration

SCANNAPIECO, ALEJANDRA CARLA; MUNTAABSKI, IRINA; LIENDO, MARÍA CLARA; NIZ, JOSE MARÍA; RUSSO, ROMINA M.; SALVADOR, RICARDO

Journal of Apicultural Research

INRA

Año: 2022

The ectoparasite Varroa destructor causes serious losses of Apis mellifera colonies and negatively impacts the beekeeping industry around the world. New control methods have beenproposed based on the RNA interference technique. Previous reports showed that parasitized honey bees fed with double-stranded RNA (dsRNA) synthesized in vitro reduce thetranscription levels of target genes in Varroa mites. An efficient and inexpensive alternativeto produce dsRNA is the use of bacteria capable of achieving high levels of in vivo synthesis.In the present study, dsRNA synthetized in vivo was used to induce gene silencing in V.destructor and evaluate their effect on the survival of both honey bees and the parasiticVarroa mites. The results evidenced that dsRNA fed to the bees engendered gene silencingin mites, inhibiting expression levels of target genes by 50%. Indeed, a reduction of 50% inVarroa survival was observed when bacterially expressed dsRNAs were administered to miteparasitized bees. Worker bees that were fed with Varroa-targeted dsRNA by oral routeshowed no survival differences compared to control bees, fed with sucrose or dsRNA-GFPsolutions. Our results demonstrated that specific dsRNA over-expressed in bacteria is capableof reducing mite survival by bee-mediated oral administration. This study provides an efficient and low-cost method for dsRNA production to control parasites and honeybee diseases.