GENUS BvA 18-01
Genetic species identification, diversity and population structure of eriophyoid grapevine mites in South African vineyards
Van Asch, B
University of Stellenbosch. Department of Genetics
Three eriophyoid mite (Acari: Trombidiformes: Eriophyidae) species of economic importance on grapevines are currently recognized:
1. Colomerus vitis hypothetically includes three strains identified based on grapevine symptoms (bud mite, leaf erineum mite and leaf curl mite) with worldwide distribution, with all three strains present in South African vineyards.
2. Colomerus oculivitis was reportedly restricted to Egypt and Saudi Arabia but it was intercepted in grapes and grapevine budwood imported to South Africa from several countries, thus raising concern about its wide distribution and potential for introduction and dissemination through global trade. Further investigation revealed taxonomic ambiguities, and it is currently uncertain whether Co. oculivitis is a valid species.
3. Calepitrimerus vitis (rust grapevine mite) is also distributed worldwide, but could be under reported, as symptoms may be partly confused with those caused by e.g. Colomerus vitis and spider mites. It is currently not known to be present in South Africa.
In vineyards, bud infertility, leaf and bunch malformation, and shortened internodes may indicate grapevine budmite infestation. However, these symptoms may also have other causes, and microscopy is currently the only confirmation method. Some important grapevine varieties (e.g. Sauvignon blanc and Cabernet Sauvignon) seem to be particularly susceptible to mite attack.
1. To investigate the genetic diversity of eriophyoid grapevine mites with focus on Colomerus spp. in South African vineyards for the discrimination of species and populations.
2. To correlate specific genetic groups of Colomerus spp. with plant symptoms and ecology to improve pest management in South African vineyards.
3. To design and validate a DNA-based test able to detect the presence / absence and identify the species/strain of Colomerus spp. in plants and commercial fruit, with focus on optimization for fast and high-throughput analyses.
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