First report of Robustodorus subtenuis on garlic plants in Poland

During the observation of a garlic plantation, a sample consisting of plants with symptoms of growth inhibition and the soil surrounding the roots was collected. Phytophagous nematodes were isolated from the soil sample as well as the garlic plant shoots, with an average density of 75 individuals per 100 mL. Microscope slides were prepared from adult individuals and subjected to morphological and morphometric analysis, as well as DNA examination. It was demonstrated that the examined nematodes belong to the species Robustodorus subtenuis. Both the female and male nematodes differed from individuals previously found in the cultivation of Narcissus and Gladiolus. On average, R. subtenuis females have shorter bodies and longer tails, with the averages calculated for the nematode population from the soil being slightly lower than the average values for nematodes from the garlic shoots. Additionally, the females found in the soil had a shorter distance from the lip region to the vulva and a shorter post-vulval sac, the length of which constituted 32 to 45% of the distance from the vulva to the anus. On average, the male bodies were shorter and had longer tails. They were also wider at the level of the anus. The average body length of males isolated from the soil, like that of the females, was lower than the average for individuals isolated from the garlic shoots. Variations in the influence of the host plant on the morphometry of the parasitic nematodes were observed. This is the first report of R. subtenuis colonizing garlic plants in Poland.