Nematicidal effects of piperine on the pinewood nematode Bursaphelenchus xylophilus

The plant-parasitic nematode Bursaphelenchus xylophilus is a notorious forest pest and the cause of pine-wilt disease which is becoming a serious issue in Asia and Europe. Few available pesticides or nematicides effectively kill B. xylophilus and the topic is the subject of on-going research. This study describes the killing effects of three constituents (piperine, piperlongumine, and piperonal) of the long pepper on the pinewood nematode juveniles. Piperine at 50 µg/mL achieved killing of B. xylophilus juveniles in 6 h, and uniquely, the pattern of killing involved rapid curling (1 h), aggregation (2 h), and death (6 h). Also, piperine adversely affected the fecundity and locomotor traits in B. xylophilus while piperine had marginal effect on the growth of plant seed germination. Computational studies showed piperine interacts with the Gln²¹⁹ residue of glutamate gated chloride ion channel (GluCl) receptor, a residue associated with receptor activation. Furthermore, the mode of action of piperine resembled that of ivermectin in in silico studies. These results suggest that piperine (the major component of peppers) be regarded a potential nematicide for pinewood nematodes and warrant further field investigations.