Chemical Signals Synchronize the Life Cycles of a Plant-Parasitic Nematode and Its Vector Beetle

• Published in: Current biology Vol. 23; no. 20; pp. 2038 - 2043
• Main Authors: Zhao, Lilin, Zhang, Shuai, Wei, Wei, Hao, Haijun, Zhang, Bin, Butcher, Rebecca A., Sun, Jianghua
• Format: Journal Article
• Language: English
• Published: England Elsevier Inc 21.10.2013
• Subjects: adults; Amino Acid Sequence; Animal Distribution; Animals; Bursaphelenchus xylophilus; Cholestenes - pharmacology; Chromones - pharmacology; Coleoptera - growth & development; Coleoptera - parasitology; Coleoptera - physiology; coniferous forests; esters; Esters - metabolism; fatty acids; Fatty Acids - metabolism; Gas Chromatography-Mass Spectrometry; Helminth Proteins - genetics; Helminth Proteins - metabolism; insect vectors; Larva - genetics; Larva - growth & development; Larva - parasitology; Larva - physiology; larvae; Molecular Sequence Data; Monochamus; Morpholines - pharmacology; Nematoda; Pinus; Pinus - parasitology; Plant Diseases - parasitology; plant parasitic nematodes; Polymerase Chain Reaction; Pupa - growth & development; Pupa - parasitology; Pupa - physiology; pupal development; Sequence Alignment; Signal Transduction; Tylenchida - genetics; Tylenchida - growth & development; Tylenchida - physiology
• ISSN: 0960-9822; 1879-0445
• DOI: 10.1016/j.cub.2013.08.041

The pinewood nematode Bursaphelenchus xylophilus has caused severe damage to pine forests in large parts of the world [1–4]. Dispersal of this plant-parasitic nematode occurs when the nematode develops into the dispersal fourth larval stage (LIV) upon encountering its insect vector, the Monochamus pine sawyer beetle, inside an infected pine tree [5–9]. Here, we show that LIV formation in B. xylophilus is induced by C16 and C18 fatty acid ethyl esters (FAEEs), which are produced abundantly on the body surface of the vector beetle specifically during the late development pupal, emerging adult, and newly eclosed adult stages. The LIV can then enter the tracheal system of the adult beetle for dispersal to a new pine tree. Treatment of B. xylophilus with long-chain FAEEs, or the PI3 kinase inhibitor LY294002, promotes LIV formation, while Δ7-dafachronic acid blocks the effects of these chemicals, suggesting a conserved role for the insulin/IGF-1 and DAF-12 pathways in LIV formation. Our work provides a mechanism by which LIV formation in B. xylophilus is specifically coordinated with the life cycle of its vector beetle. Knowledge of the chemical signals that control the LIV developmental decision could be used to interfere with the dispersal of this plant-parasitic nematode. •Monochamus beetles produce large quantities of C16 and C18 FAEEs during eclosion•Long-chain FAEEs specifically promote LIV formation in B. xylophilus•Insulin/DAF-12 pathways control LIV formation and are possibly modulated by FAEEs