TOWARDS THE MOLECULAR CHARACTERIZATION OF THE CHANNEL SODIUM GENE IN DERMANYSSUS GALLINAE ACARICIDE RESISTANT ISOLATES FROM ITALY

In the last years, acaricide resistance in populations of Dermanyssus gallinae was recurrently suspected. This might be attributed to the genetic variability of the acaricide target genes. Data on target coding genes and the possible polymorphisms involved in such resistance remains completely unexplored in D. gallinae. In order to investigate mutations in the gene coding the pyrethroid's target, we screened the literature on pyrethroid resistance and the GenBank database to identify mutations in other Acari and run molecular experiments to sequence the right portions of the voltage gated sodium channel gene (VGSC). Seventy-three sequences of the VGSC gene from several species of Acari belonging to Tetranychidae, Sarcoptidae, Varroidae and Ixodidae families were downloaded from Nucleotide-GenBank. After sequence alignment, the VGSC sequence from domain II to IV was split into 3 different parts in order to design primer pairs able to amplify largely overlapping fragments, for subsequent Sanger sequencing. Highest nucleotide variations were observed among acarine VGSC. A total of 26 primer pairs were designed using Primer BLAST program and different amplicons were sequenced. None of the obtained sequences were related to the D. gallinae sodium channel gene suggesting that the gene is very different even between D. gallinae and the most closely related mite species available in the GenBank (Varroa destructor). Further experiments are ongoing. Once the gene will be molecularly characterized, the D. gallinae populations -with contrasted susceptibility to pyrethroids-, will be tested in order to estimate the frequency of mutations related to acaricide resistance.