Investigation of the nematicidal mechanisms of cover crop-derived extracts on pest (Meloidogyne incognita) and beneficial (Panagrellus redivivus) nematode species under laboratory conditions

Root-knot nematodes ( Meloidogyne spp.) cause significant damage to many crops and their control remains a challenging task even today. Nowadays, the use of cover crops is one of the key elements of regenerative agriculture due to its numerous benefits. For example, cover crops can reduce the damage and population of Meloidogyne , however, less attention has been paid to their effects and mode of actions on non-target beneficial nematodes. In this experiment, we examined the effects of fresh and dry root extracts derived from four cover crops (rye, radish, red clover, and hairy vetch) on the plant-parasitic nematode M. incognita and the bacteriophagous nematode P. redivivus in area choice, and mortality tests.Dry extract of hairy vetch from 1%, dry extract of radish from 0.5%, and 5% extract of rye and red clover showed mortality rates of over 90% in the case of M. incognita . All root extracts had repellent effect on M. incognita . In the case of P. redivivus , only a 5% root extract of the plants had a lethal effect, but it was never as strong as that observed for M. incognita . A 5% radish root extract was the only one to show significant toxicity. Both dry and fresh extracts of each plant had an attractive effect on P. redivivus . These results may be useful for further studies with cover crops focusing on M. incognita infection and infection suppression and they also draw attention to the need for research into methods that consider the effects on beneficial nematodes.