title: Chemical signals synchronize the life cycles of a plant-parasitic nematode and its vector beetle.
abstract: 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.
authors.affiliation: State Key Laboratory of Integrated Management of Pest Insects and Rodents, Institute of Zoology, Chinese Academy of Sciences, Beijing 100101, People's Republic of China; Department of Chemistry, University of Florida, Gainesville, FL 32611, USA.
authors.forename: Lilin
authors.initials: L
authors.lastname: Zhao
authors.forename: Shuai
authors.initials: S
authors.lastname: Zhang
authors.forename: Wei
authors.initials: W
authors.lastname: Wei
authors.forename: Haijun
authors.initials: H
authors.lastname: Hao
authors.forename: Bin
authors.initials: B
authors.lastname: Zhang
authors.forename: Rebecca A
authors.initials: RA
authors.lastname: Butcher
authors.forename: Jianghua
authors.initials: J
authors.lastname: Sun
mesh_terms: D000595:Amino Acid Sequence; D063147:Animal Distribution; D000818:Animals; D002782:Cholestenes / Q000494:pharmacology; D002867:Chromones / Q000494:pharmacology; D001517:Coleoptera / Q000254:growth & development / Q000469:parasitology* / Q000502:physiology*; D004952:Esters / Q000378:metabolism; D005227:Fatty Acids / Q000378:metabolism; D008401:Gas Chromatography-Mass Spectrometry; D015801:Helminth Proteins / Q000235:genetics / Q000378:metabolism; D007814:Larva / Q000235:genetics / Q000254:growth & development / Q000469:parasitology / Q000502:physiology; D008969:Molecular Sequence Data; D009025:Morpholines / Q000494:pharmacology; D028223:Pinus / Q000469:parasitology*; D010935:Plant Diseases / Q000469:parasitology*; D016133:Polymerase Chain Reaction; D011679:Pupa / Q000254:growth & development / Q000469:parasitology / Q000502:physiology; D016415:Sequence Alignment; D015398:Signal Transduction; D017187:Tylenchida / Q000235:genetics / Q000254:growth & development / Q000502:physiology*
chemical_list: D002782:Cholestenes; D002867:Chromones; D004952:Esters; D005227:Fatty Acids; D015801:Helminth Proteins; D009025:Morpholines; C533798:delta7-dafachronic acid; C085911:2-(4-morpholinyl)-8-phenyl-4H-1-benzopyran-4-one