Mosquitoes (Diptera: Culicidae) As Dirofilaria Vectors In Tula Region, Russia

Abstract:
This study was carried out to investigate the potential vectors and mosquito infection rates of Dirofilaria immitis and D. repens in Tula region which is located in central part of Russia. Mosquitoes were captured throughout three mosquito seasons (2013–2015). A total of 719 genomic DNA pools, extracted and grouped according to the species and collection site (1–5 specimens/pool) from 2877 mosquito specimens, were examined by PCR using species-specific primers for D. immitis and D. repens. DNA extraction was performed separately to thorax-heads and abdomens in order to determine infective and infected mosquito specimens, respectively. Mosquito fauna is represented by 18 species belonging to 6 genera. The most abundant species was determined as Och. cantans (41.8%), Cx. pipiens (9.5%), Och. cataphylla (8.9%), Ae. geniculatus (6.9%). The minimum infection rates (MIRs) for Dirofilaria infection were calculated as 2.6% (1.5% and 1.1% for D. immitis and D. repens, respectively). Filarial DNAs were found in 12 species but most frequently in Ae. geniculatus, Och. punctor, Och. sticticus, Ae. cinereus, Och. cantans. MIRs for these specimens were established as 4.0%, 3.9%, 3.7%, 3.5%, 3.2%, respectively. The PCR results indicated that filarial DNAs were detected mainly in mosquito abdomens: 39/719 (5.4%) and 30/719 (4.2%) pools were positive for D. immitis and D. repens infection, respectively. In thorax-heads DNAs were detected less frequently: 9/719 (1.3%) and 6/719 (0.8%) pools were positive for D. repens and D.  immitis DNAs, respectively. Four species of mosquitoes (Ae. vexans, Ae. geniculatus, Cx. pipiens, Och. cantans) carried infective stages of dirofilarial nematodes and could be the main potential vector of D. immitis and D. repens in Russia.