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Genetic species identification, diversity and population structure of eriophyoid grapevine mites in South African vineyards

Project Number
GENUS BvA 18-01

Project title
Genetic species identification, diversity and population structure of eriophyoid grapevine mites in South African vineyards

Project leader
Van Asch, B

Institution
University of Stellenbosch. Department of Genetics

Team members
Rhode, C
Allsopp, E
Addison, P
Craemer, C
Saccaggi, D

Completion date

2021

EXECUTIVE SUMMARY

Objectives and Rationale
The diversity of eriophyoid grapevine mites is poorly understood, in South Africa and worldwide. This study assessed the species diversity of eriophyoid grapevine mites found in bud and leaf blister in the Western Cape using a combination of DNA-based and electron microscopy analyses.

Methods
Genetic diversity was assessed using Sanger sequencing and a novel species-specific multiplex PCR method. Morphological diversity was assessed using cryo-scanning electron microscopy (cryo-SEM).

Key Results
Grapevine mites include at least five genetic groups likely representing distinct species, based on sequence data from South Africa and other countries. Different genetic groups are often co-present in the same plant tissue. Some associations (but not exclusive) between genetic groups and plant symptoms were found. Electron microscopy showed little morphological differentiation.

Key Conclusion of Discussion
Our results showed that grapevine mites in South Africa and worldwide comprise at least five species that can be distinguished genetically but not morphologically distinguishable by light or electron microscopy. Three of these species exist in vineyards in the Western Cape but are not associated with specific plant symptoms.

Take Home message for Industry
Grapevine mites comprise at least five species not specifically associated with buds, erinea or leaves. This opens many questions regarding the biology and roles of the different species.

Final Report.pdf

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