Colomerus vitis

Colomerus vitis 

Colomerus vitis (Acari: Trombidiformes: Eriophyidae) includes bud, leaf curl, and leaf blister eriophyoid mites that cause significant economic damage to grapevines worldwide. It has been hypothesised that different genetic or morphological strains of C. vitis cause the three different plant symptoms. [. . . ] Bud and blister mites were significantly associated with different genetic groups. [. . . ] In conclusion, these results indicate that “C. vitis” includes several genetic groups of sufficient diversity to justify the proposal of separate species, rather than strains of a single species each associated with different plant symptoms. These putative species occur in mixed populations within the different plant symptoms, and do not appear to be morphologically unique enough to allow morphological separation of all five species detected here.

The leaf blister (erineum) mite strain (Figure 1.2 B, C) feeds on the underside of the leaves leading to gall formation on the top surface of the leaves (Smith Meyer, 1981). Damaged leaf cells multiply and form fine white or yellow hairs, causing felt-like patches called trichomogenic erinea on the under surface of infested leaves (Slepyan, 1969). Patches form in 10 to 30 days from when the mites first start feeding, depending on the leaf development rate. The patches initially appear white, then turn yellow and finally reddishbrown. Patches arise mainly on the apical leaf part, above the upper parts of the incisions. Leaf erinea decrease the photosynthesis ability of the leaf, but usually not to a physiologically damaging point. Thus, the leaf blister strain of C. vitis is usually not considered a serious economic pest. 

Females of the leaf blister strain overwinters under outer scales of dormant buds (Duso and DeLillo, 1996; Smith Meyer, 1981) and sometimes under bark crevices (Duso and De Lillo, 1996). The females start moving to unfolding leaves as the bud swells in spring, where they start inducing erinea and reproducing (Duso and DeLillo, 1996; Smith Meyer, 1981). Development mostly occurs in the erinea. The first generation requires approximately 25 days, but the subsequent six generations in the season can develop much faster (Mathez, 1965). In late spring and early summer, the mites migrate to apical leaves and induce new erinea. In late summer and the beginning of autumn, the females start migrating to their overwintering sites in the buds. Since these mites are very sensitive to desiccation, they only migrate in the evening to survive (Smith Meyer, 1981).

Solving the “Colomerus vitis conundrum”: genetic evidence reveals a complex of highly diverged groups with little morphological differentiation