Colomerus vitis (Acari: Trombidiformes: Eriophyoidea): some morphometric, biomolecular and biological aspects comparing deutogyne versus protogyne forms.

Eriophyoid mites overwinter by a winter form (deutogyne) morphologically distinct from the spring-summer form (protogyne). Deutogyne is well distinct and known for a part of eriophyoids. Grapevine erineum mite, Colomerus vitis (Pagenstecher), is widespread in the main world viticultural areas, was recently demonstrated vector Grapevine pinot gris virus. Its females overwinter mainly under outer scales of buds and a deutogyne was described but not perfectly distinct from the protogyne. A morphometric, biomolecular and biological approach was applied in order to better characterize deutogynes versus protogynes. Buds or leaves of Luisa infested by C. vitis were sampled 6 times from the same vineyard between December 2015 and January 2017. Females were studied for about 70 traits commonly used for taxonomic identification. Kruskal-Wallis test was applied for the measured populations. ITS1 was investigated in individuals collected from buds (winter) and erinea (spring). Groups of protogynes and deutogynes were separately submerged in water or vaseline, at 5/25±1°C, and mite survival was assessed every week/day, respectively. Data were analyzed by regression analysis. Length of foreleg seta l’ and hindleg seta ft’, and numbers of smooth dorsal semiannuli were significantly different between protogynes and deutogynes. ITS1 analysis confirmed the homogeneity of these populations. The study demonstrated the presence of population composed by protogynes and deutogynes in July and September 2016. In April and May 2016 were collected only protogynes, whereas in December 2015 and January 2017 were collected only deutogynes, as expected. Deutogynes showed a higher survival than the protogynes in all experimental conditions.