To find novel nematicides, we screened
the nematicidal
activity
of compounds in our laboratory compound library. Interestingly, the
compound N-((1R,2R)-2-(2-fluoro-4-(trifluoromethyl)phenyl)cyclopropyl)-2-(trifluoromethyl)benzamide
(W3) showed a broad spectrum and excellent nematicidal
activity. The LC50 values of compound W3 against
second-stage juveniles of Bursaphelenchus xylophilus (B. xylophilus), Aphelenchoides
besseyi, and Ditylenchus destructor are 1.30, 1.63, and 0.72 mg/L, respectively. Nematicidal activities
of compound W3 against second-stage juveniles of Meloidogyne incognita were 87.66% at 100 mg/L. Meanwhile,
compound W3 can not only observably inhibit the feeding,
reproduction, and egg hatching of B. xylophilus but can also effectively promote the oxidative stress adverse reactions
of nematodes and cause intestinal damage. Compound W3 can promote the production of MDA and inhibit the activities of
defense enzymes SOD and GST in B. xylophilus. Compound W3 can affect the transcription of genes
involved in regulating the tricarboxylic acid cycle in nematodes,
resulting in weakened nematode respiration and reduced nematode activity
and even death. In addition, compound W3 had good inhibitory
activity against five pathogenic fungi. Among them, the EC50 of compound W3 against Fusarium graminearum was 8.4 mg/L. In the future, we will devote ourselves to the toxicological
and structural optimization research of the candidate nematicide W3.