The Use of the Bayes Factor for Identification of Culex pipiens and C. torrentium (Diptera: Culicidae) Based on Morphometric Wing Characters

The probabilistic approach was applied to morphometric identification of Culex pipiens pipiens / torrentium mosquito females collected in the Sablino caves (Leningrad Province of Russia). The distances between landmarks of the radial wing veins r (2+3) and r 3 were measured, and the frequency distribution of the r (2+3) / r 3 wing vein index was analyzed. The obtained distribution had two maxima coinciding with the distribution maxima obtained earlier by other authors for the German populations of Culex pipiens pipiens and C. torrentium . Most specimens in the sample from the Sablino caves grouped at the maximum of the Culex pipiens normal distribution. We propose to use the Bayes factor (BF) to select those mosquito females which most likely belong to C. p. pipiens . In the sample studied, the BF value was greater than 10 for 72.5% of the specimens, which was interpreted as strong or very strong evidence in favor of C. p. pipiens . For 16.5% of individuals the BF value was greater than 0.1 and smaller than 10, providing moderate or weak evidence in favor of one of the two species. Overall, 11% of the females had BF values smaller than 0.1, this being strong or very strong evidence in favor of C. torrentium . To increase the reliability of C. p. pipiens selection, the specimens with the highest BF values should be chosen.