Population Structure, Diversity and Reproductive Mode of the Grape Phylloxera (Daktulosphaira vitifoliae) across Its Native Range

Abstract

Grape Phylloxera, Daktulosphaira vitifoliae, is a gall-forming insect that feeds on the leaves and roots of many Vitis species. The roots of the cultivated V. vinifera cultivars and hybrids are highly susceptible to grape phylloxera feeding damage. The native range of this insect covers most of North America, and it is particularly abundant in the eastern and central United States. Phylloxera was introduced from North America to almost all grape-growing regions across five of the temperate zone continents. It devastated vineyards in each of these regions causing large-scale disruptions to grape growers, wine makers and national economies. In order to understand the population diversity of grape phylloxera in its native range, more than 500 samples from 19 States and 34 samples from the introduced range (northern California, Europe and South America) were genotyped with 32 simple sequence repeat markers. STRUCTURE, a model based clustering method identified five populations within these samples. The five populations were confirmed by a neighbor-joining tree and principal coordinate analysis (PCoA). These populations were distinguished by their Vitis species hosts and their geographic locations. Samples collected from California, Europe and South America traced back to phylloxera sampled in the northeastern United States on V. riparia, with some influence from phylloxera collected along the Atlantic Coast and Central Plains on V. vulpina. Reproductive statistics conclusively confirmed that sexual reproduction is common in the native range and is combined with cyclical parthenogenesis. Native grape phylloxera populations were identified to be under Hardy-Weinberg equilibrium. The identification of admixed samples between many of these populations indicates that shared environments facilitate sexual reproduction between different host associated populations to create new genotypes of phylloxera. This study also found that assortative mating might occur across the sympatric range of the V. vulpina west and V. cinerea populations.

Population Diversity of Grape Phylloxera in California and Evidence for Sexual Reproduction

“…The fact that the foliar phylloxera samples had low levels of genetic diversity suggests that they originated from a single insect or an asexual colony of foliar phylloxera. In a separate study, we investigated the population structure of foliar phylloxera in its native range where a large collection of samples was obtained and genotyped with SSR markers (Lund et al 2017). The California foliar sample, WEO4802, was identified by STRUCTURE as an admixture between the V. riparia and the V. vulpina populations and was similar to samples that were collected from Indiana where these two Vitis species overlap.…”

Grape phylloxera (Daktulosphaira vitifoliaeFitch) in Argentina: ecological associations to diversity, population structure and reproductive mode

“…In this study, the term biotype is used as proposed by Forneck et al (). In addition, three Peruvian foliar samples from an earlier study (Lund et al ) were utilised as an outgroup. The results obtained from the hierarchical clustering were supported by a principal coordinates analysis (PCoA).…”

“…For comparison with international data, 189 samples from roots and leaves (161 samples from the USA, three from Brazil, four from Uruguay, seven from Austria, six from France and eight from Hungary) were added (Lund et al ) and analysed through PCoA. The PCoA was carried out with DARWIN software (version 5.0.158) (Perrier and Jacquemoud‐Collet ).…”

First European leaf-feeding grape phylloxera (Daktulosphaira vitifoliae Fitch) survey in Swiss and German commercial vineyards

“…Available SSR data from 502 grape phylloxera MLGs were obtained from Lund et al (2017) for comparison with international data. This dataset mainly corresponds to samples collected from grape phylloxera's native range (USA), but also includes some samples from introduced ranges of Argentina (2), Brazil (3), California (5), Peru (3), Uruguay (4), Austria (7) and Hungary (8).…”