Host Range and Genetic Characterization of Ditylenchus dipsaci Populations from Eastern Canada

Abstract

The stem and bulb nematode, Ditylenchus dipsaci, is a plant-parasitic nematode affecting over 500 plant species worldwide. Since 2012, garlic producers from Ontario and Quebec have been particularly affected with economic losses caused by this pest. Reproduction of D. dipsaci on a particular host depends on its biological race, and races are unknown for these populations from eastern Canada. As a polyphagous pest, D. dipsaci can possibly be a threat and have negative impact on many crops grown in Quebec, such as field and vegetable crops (e.g., onion). In this study, the host range of four populations of D. dipsaci from Quebec and Ontario was determined in a greenhouse experiment using 11 crops. Garlic, onion, and green onion showed high susceptibility to the nematode, whereas reproduction on potato was poor. No reproduction was observed on corn, soybean, barley, alfalfa, mustard, carrot, and lettuce. These crops could therefore be used as rotational crops in a control program. Thirty-two populations of D. dipsaci were also genetically characterized using genotyping-by-sequencing. The comparison of allele frequencies at 481 loci showed that most of the populations had a genotype similar to a reference population from northern Ontario. However, a sample from eastern Quebec exhibited a distinct genotype and will require further phenotyping in a greenhouse to preclude the possibility of a different race.

Susceptibility of different plant species to two populations of Ditylenchus dipsaci Kühn, 1857 (Tylenchida: Anguinidae) from Turkey

“…Consistent with our results, reproduction factor of garlic as control plant was higher than 6 (excellent host) and wheat was less than 1 (non-host). Recently, Poirier et al (2019) reported barley, carrot, lettuce and maize as non-hosts for a garlic population of D. dipsaci from Canada, and therefore useful for rotation in D. dipsaci-infested garlic production areas in Canada, these results are similar to our results. They also found the nematode reproduced well on garlic and onion, and less well on potatoes, as we found in our study.…”

Determination of the host status of some plant species with four different garlic populations of Ditylenchus dipsaci (Kühn, 1857) Filipjev, 1936 (Tylenchida: Anguinidae)

“…In a recent study (Poirier et al, 2019) in Canada, lucerne and lettuce were found to be non-hosts of a garlic population of D. dipsaci, similar to our study. Also, consistent with the findings of the present study, Hajihassani et al (2016) reported that wheat was a non-host, chickpea cultivars were poor hosts and garlic a good host.…”

Virulence and pathogenicity of four Ditylenchus dipsaci populations on sugar beet

“…This study did not aim to determine the biological race of the four D. dipsaci populations. A host preference investigation is, to date, the only way to determine a D. dipsaci population's biological race (Poirier et al, 2019). An easy method to determine the biological race of field population would help growers to adapt their crop rotation and reduce nematode pressure by avoiding host plant species.…”

“…The reproduction of polyphagous races varies greatly among host plant species (Whitehead et al, 1987). Qiao et al (2013) and Poirier et al (2019) reported distinct genotypes among D. dipsaci populations within a geographic region and between neighboring farms. Esquibet et al (1998) succeeded to molecularly distinguish the species D. dipsaci sensu lato from the giant race D. gigas, recently singled out as new species (Vovlas et al, 2011).…”