title: Nematotoxicity of drupacine and a Cephalotaxus alkaloid preparation against the plant-parasitic nematodes Meloidogyne incognita and Bursaphelenchus xylophilus.
abstract: BACKGROUND
  Species of Cephalotaxus (the plum yews) produce nematotoxic compounds of unknown identity. Consequently, bioassay-guided fractionation was employed to identify the compound(s) in Cephalotaxus fortunei twigs and leaves with activity against plant-parasitic nematodes.
  
  
  RESULTS
  A crude alkaloid extract, particularly drupacine, was responsible for much of the nematotoxicity. The ED50 of drupacine for Bursaphelenchus xylophilus was 27.1 µg mL⁻¹, and for Meloidogyne incognita it was 76.3 µg mL⁻¹. Immersion of M. incognita eggs in 1.0 mg mL⁻¹ crude alkaloid extract (the highest tested concentration) reduced hatch by 36%; immersion of second-stage juveniles (J2) resulted in 72-98% immobility. Crude alkaloid extract and drupacine suppressed protease activity in extracts of the microbivorous nematode Panagrellus redivivus by 50% and 80%, respectively. Application of 0.02-0.5 mg mL⁻¹ crude alkaloid extract to soil with M. incognita inoculum did not significantly reduce pepper plant shoot length or weight, compared with nematode-inoculated, water-treated controls, but the number of eggs and J2 per root system respectively decreased by 69% and 73% at 0.5 mg mL⁻¹.
  
  
  CONCLUSIONS
  Drupacine and a crude alkaloid extract suppress nematode hatch, activity of mixed life stages, and population numbers on plant roots. This is the first demonstration of nematotoxicity of crude Cephalotaxus alkaloids and drupacine.
authors.affiliation: College of Natural Resources and Environment, South China Agricultural University, Tianhe District, Guangzhou City 510642, Guangdong Province, China.
authors.forename: Yanhua
authors.initials: Y
authors.lastname: Wen
authors.forename: Susan L F
authors.initials: SL
authors.lastname: Meyer
authors.forename: Edward P
authors.initials: EP
authors.lastname: Masler
authors.forename: Fengxian
authors.initials: F
authors.lastname: Zhang
authors.forename: Jinling
authors.initials: J
authors.lastname: Liao
authors.forename: Xiaoyi
authors.initials: X
authors.lastname: Wei
authors.forename: David J
authors.initials: DJ
authors.lastname: Chitwood
mesh_terms: D000470:Alkaloids / Q000633:toxicity*; D000818:Animals; D000969:Antinematodal Agents / Q000633:toxicity*; D002212:Capsicum / Q000469:parasitology*; D032483:Cephalotaxus / Q000737:chemistry*; D006248:Harringtonines / Q000633:toxicity*; D010571:Pest Control; D010935:Plant Diseases / Q000469:parasitology*; D010936:Plant Extracts / Q000633:toxicity*; D017187:Tylenchida / Q000187:drug effects* / Q000254:growth & development
chemical_list: D000470:Alkaloids; D000969:Antinematodal Agents; D006248:Harringtonines; D010936:Plant Extracts; C007562:drupacine
keywords: Bursaphelenchus; Meloidogyne; Panagrellus; alkaloid; natural product; nematicide; nematode; phytochemical; pinewood nematode; root-knot nematode