Nematicidal activities and preliminary mechanisms of action of natural quinones against plant parasitic nematodes.

Plant-parasitic nematodes cause substantial economic losses in agriculture globally. Chemical nematicides with cost-effectiveness and immediate availability continue to be widely used; however, their environmental and health risks have driven the discovery of eco-friendly alternatives. In this study, 60 natural quinones were screened for nematicidal activity to discover new nematicides that are environmentally friendly. Therefore, by evaluating the activities of these compounds against B. xylophilus, A. besseyi, and D. destructor, and find that 5,8-dihydroxy-1,4-naphthoquinone (DHNQ) exhibited excellent nematicidal activities against three nematodes with LC50 values of 7.7, 6.4, and 6.5 μg/mL at 48 h, respectively, which became the key discovery in the work. DHNQ could cause the body of B. xylophilus to dry out and crumple, and with visible voids on the cuticle surface. Moreover, the DHNQ treatment not only led to significant inhibition of feeding, reproduction, and egg hatching in B. xylophilus populations but also significantly increased the contents of ROS and lipids in B. xylophilus. Furthermore, DHNQ treatment upregulate the expression level of genes related to the metabolism of xenobiotics by cytochrome P450, and then cause a certain degree of damage to B. xylophilus. However, the underlying targeting and signaling pathways of DHNQ against plant-parasitic nematodes need to be further explored. The present work indicates that DHNQ may serve as a promising lead structure for development of new nematicides to control plant parasitic nematodes.