Biological pesticides and solvents with low toxicity reduce motility and activity of Bursaphelenchus xylophilus

Abstract

Summary Pine wilt disease (PWD), caused by the pine wood nematode, Bursaphelenchus xylophilus, is an international quarantine forest disease that damages pine forests over extensive areas and causes massive economic losses. To provide valuable guidelines on screening pesticides against B. xylophilus and the selection of common solvents, we investigated the effects of different concentrations of emamectin benzoate, matrine and four solvents (methanol, ethanol, acetone and dimethyl sulfoxide) on the mortality and locomotor behaviour of B. xylophilus. Emamectin abamectin has nematicidal activity and mitigates locomotor activity of B. xylophilus at a low concentration. The LC50 of emamectin benzoate was 0.0354 mg l−1 at 72 h. Bursaphelenchus xylophilus mortality following exposure to matrine was low; however, nematode locomotor activity decreased by 62.5% following exposure to 500 mg l−1 matrine for 8 h. Additionally, B. xylophilus locomotor activity decreased significantly following exposure to 5 and 10% methanol, ethanol, acetone and dimethyl sulfoxide (DMSO) when compared with that of the water control. Emamectin benzoate and matrine, and high concentrations of four solvents (methanol, ethanol, acetone, and DMSO) inhibit B. xylophilus movement, which, in turn, could affect nematode infectivity. Moreover, low concentrations of non-lethal doses of emamectin benzoate should be considered for application in the control of nematodes, with matrine being an environmentally friendly and potentially nematicidal agent.