Pine wood nematode (PWN), Bursaphelenchus xylophilus causes devastating damage to pines worldwide. To develop new agent for controlling PWN, many kinds of compounds have been evaluated for their nematicidal activity against PWN with different bioassay system according to researchers. Therefore, it was hard to directly compare their activity. To establish standard procedure for bioassay, nematicidal activity of abamectin was tested and compared in different conditions. The tested conditions are following: 1) nematode density: 100 and 1000 nematodes in 0.1 and 1 mL, 2) amount of reagent: 0.1, 1, 10, 100 uL of abamectin solution which same amount of abamectin was dissolved in. We will report the results of tested nematicidal activity according to conditions.

Pine wood nematode (PWN), Bursaphelenchus xylophilus causes devastating damage to pines worldwide. To develop new agent for controlling PWN, 43 alkyloxyalcohols were synthesized and nematicidal activity was tested against PWN. As a control, monochamol, which reported to have nematicidal activity was also tested. The nematicidal activity was diffferent according to total carbon chain length in compounds and carbon numbers of diol derivates. The odd numbered carbon diol derivates (ROC5OH, ROC7OH, ROC9OH) showed weak activity. The compounds which had C14H30O2 formula (C11OC3OH, C10OC4OH, C8OC6OH, C6OC8OH) showed the same level nematicital activity as that of monochamol in the term of LC50 value. Thee compounds which had C15H32O2 and C13H28O2 formulas (C12OC3OH, C11OC4OH, C12OC3OH, C10OC3OH, C9OC4OH, C5OC8OH) were followed.

Pine trees are ecologically important in Korea. They are seriously imperiled by Pine wilt disease (PWD), by pine wood nematode (PWN, Bursaphelenchus xylophilus). Here, we isolated and characterized bacterial endophytes (BEs) from pine trees in Korea for biological control of PWN using BE metabolites. Using culture-dependent approach BE isolates were extracted from three tissues (needles, stems, and roots) of four pine species across 18 sampling sites in Korea. Bacterial isolates were characterized into 389 distinct isolates based on 16S rDNA sequencing. Ethyl acetate crude extracts (CEs) of bacterial liquid cultures were prepared using ethyl acetate and screened for nematicidal activity against PWN. BEs (1,622 isolates) were isolated; their taxonomic binning resulted in 215 operational taxonomic units (OTUs). Analysis of species richness and Shannon’s diversity of the three tissues revealed that BEs colonized the needles more than the stem and root tissues. Furthermore, based on nematicidal activity screening of 389 isolates, 44 BEs were identified, with two isolates exhibiting a significant inhibitory activity against PWN. Taken together, these data revealed numerous nematicidal BEs in pine trees, providing new insights that can serve as an effective and promising alternative approach to combat PWD.

Pine wood nematode (PWN), Bursaphelenchus xylophilus causes devastating damage to pines worldwide. To develop new agent for controlling PWN, alkyloxyalcohols(A-H) were synthesized and nematicidal activity was tested against PWN. As a control, monochamol, which reported to have nematicidal activity was also tested. The nematicidal activity was diffferent according to carbon chain length in compounds. LC50 values of F, G and H were as same as that of monochamol. However A-E which have shorter carbon length than F-H showed weak nematicidal activity.

The nematicidal activity of Phellodendron amurense rhizome-derived materials (methanol extract) toward Meloidogyne Spp. second-stage juveniles (J2) and these effects on Cucumis sativus and Cucumis melo. Results were compared with these of fosthiazate. J2 was examined using 24-well plate tests, pot bioassays (C. sativa and C. melo) and Field trials (C. melo). In 24-well plate test with J2, methanol extract of P. amurense exhibited 98.7% and 69.8% mortality at 0.25 and 0.125 mg/ml toward J2, respectively, whereas Fosthiazate showed 100% mortality at 1 mg/ml. In pot bioassays with J2, P. amurense rhizome methanol extract gave 79.5% and 57.4% mortality at 2ℓ/m2(1,000x) and 2ℓ/m2(2,000x)/3kg soil from C. sativa and 73.7% and 53.3% mortality at 2ℓ/m2(1,000x) and 2ℓ/m2(2,000x)/3kg soil from C. melo, respectively. In Field test at C. melo in greenhouse showed 55.1% and 26.9% mortality at 2ℓ/m2(1,000x) and 2ℓ/m2(2,000x) applied soil. P. amurense rhizome-derived materials, merit further study as potential root-knot nematode control agents because of their nematicidal activity.

In this study, we investigated the nematicidal activities of 102 Korean domestic plant extracts which have not been tested before against B. xylophilus. Nematicidal activity of plant extracts were varied according to plant species and extraction part. Among 102 plant extracts, 42 plant extracts in 22 families showed >50% nematicidal activity against pine wood nematode at 10 mg/mL concentration. Among 31 wood extracts, very strong nematicidal activity (100%) was produced from extract of Neolitsea aciculate, Prunus sargentii and Rhus chinensis at 10 mg/mL concentration. Extracts from Camellia japonica, Carpinus cordata, Daphniphyllum macropodum, Eucommia ulmoides, Ilex cornuta, Myrica rubra, Vaccinium bracteatum, and Zelkova serrata showed strong nematicidal activities (80-99%). The other samples exhibited activities <80%. In a test with leaf extracts, strong neamticidal activity was observed in extract of Machius japonica (100%) followed by Picea koraiensis (99.4%), Meliosma oldhamii (82.7%), and Zelkova serrata (81%). The other 37 plant species revealed <80% mortality. Strong nematicidal activity (>80%) was observed from bark extract of Carpinus cordata, Comus kousa, Cryptomeria japonica, Machius japonica, Quercus glauca and Zelkova serrata. Nematicidal activity of other 19 bark extracts was less than 80%. Twig extract of Smilax china and fruit extract of Forsythia koreana showed 86.6 and 81.4% nematicidal activity at 10 mg/mL concentration, respectively.

Nematicidal activity of aliphatic compounds was tested against pien wood nematode, Bursaphelenchus xylophilus. There was a significant difference in nematicidal activity among function groups. In a test with alkanols and 2-alkenols, compounds with C8-C11 chain length showed 100% nematicidal activity at 0.5 mg/mL concentration. C6-C10 2-alkenals exhibited >95% nematicidal activity, but the other compounds with C11-C14 chain length showed weak activity. Nematicidal activity of alkanoic acids with C7-C11 chain length was strong. Whole compounds belonging to hydrocarbons, alkanals and alkanoic acetate showed weak nematicidal activity at 0.5 mg/mL concentration. Nematicidal activity of compounds which showed strong nematicidal activity at 0.5 mg/mL concentration was tested at a lower concentration. At 0.25 mg/mL concentration, whole compounds except C8 alkanol, C8 2-alkenol and C7 alkanoic acid showed >80% nematicidal activity. C9-C11 alkanols, C10-C11 2-alkenols, C8-C9 2-alkenals and C9-C10 alkanoic acids showed >80% nematicidal activity at 0.125 mg/mL concentration. Only C11 alkanol exhibited strong nematicidal activity at 0.0625 mg/mL concentration

The nematicidal activity of Kaempferia galanga rhizome-derived materials (methanol extract, steam distillate, and powder) toward M. incognita second-stage juveniles (J2) was examined using residual contact toxicity and pot bioassays. In residual contact toxicity bioassays with J2, the active principles of K. galanga rhizome were identified as the phenylpropanoids ethyl cinnamate (EC, 1) and ethyl-p-methoxycinnamate (EMC, 2) by spectroscopic analysis. EC exhibited 95% and 49% mortality at 0.06 and 0.04 mg/ml toward J2, respectively, whereas EMC showed 98% and 63% mortality at 0.1 and 0.08 mg/ml. In pot tests with J2, K. galanga rhizome methanol extract gave 92% and 82% mortality at 100 and 20 mg/50g soil, respectively. Steam distillate gave 88% and 68% mortality at 85 and 42.5 mg/50g soil, respectively, whereas rhizome powder provided 83% and 62% mortality at 400 and 200 mg/50g soil. K. galanga rhizome-derived materials, particularly EC and EMC, merit further study as potential root-knot nematode control agents or leads because of their great activity as a nematicide.

Commercial plant essential oils from 27 plant species were tested for their nematicidal activities against the pinewood nematode, Bursaphelenchus xylophilus. Good nematicidal activity against B. xylophilus was achieved with essential oils of coriander (Coriandrum sativum), styrax (Liquidamber orientalis) and valerina (Valeriana wallichi). Analysis by gas chromatography-mass spectrometry led to identification of 26, 10 and 4 major compounds from coriander (Coriandrum sativum), styrax (Liquidamber orientalis) and valerina (Valeriana wallichi) oils, respectively. These compounds from three plant essential oils were tested individually for their nematicidal activities against the pine wood nematode. Among compounds, benzaldehyde, trans-cinnamyl alcohol, cis-asarone, octanal, nonanal, decanal, trans-2-decenal, undecanal, dodecanal, decanol, and trans-2-decen-1-ol showed strong nematicidal activity. The essential oils and their described herein merit further study as potential nematicides against the pine wood nematode.