title: Olfaction shapes host-parasite interactions in parasitic nematodes.
abstract: Many parasitic nematodes actively seek out hosts in which to complete their lifecycles. Olfaction is thought to play an important role in the host-seeking process, with parasites following a chemical trail toward host-associated odors. However, little is known about the olfactory cues that attract parasitic nematodes to hosts or the behavioral responses these cues elicit. Moreover, what little is known focuses on easily obtainable laboratory hosts rather than on natural or other ecologically relevant hosts. Here we investigate the olfactory responses of six diverse species of entomopathogenic nematodes (EPNs) to seven ecologically relevant potential invertebrate hosts, including one known natural host and other potential hosts collected from the environment. We show that EPNs respond differentially to the odor blends emitted by live potential hosts as well as to individual host-derived odorants. In addition, we show that EPNs use the universal host cue CO(2) as well as host-specific odorants for host location, but the relative importance of CO(2) versus host-specific odorants varies for different parasite-host combinations and for different host-seeking behaviors. We also identified host-derived odorants by gas chromatography-mass spectrometry and found that many of these odorants stimulate host-seeking behaviors in a species-specific manner. Taken together, our results demonstrate that parasitic nematodes have evolved specialized olfactory systems that likely contribute to appropriate host selection.
authors.affiliation: Howard Hughes Medical Institute, Division of Biology, California Institute of Technology, Pasadena, CA 91125, USA.
authors.forename: Adler R
authors.initials: AR
authors.lastname: Dillman
authors.forename: Manon L
authors.initials: ML
authors.lastname: Guillermin
authors.forename: Joon Ha
authors.initials: JH
authors.lastname: Lee
authors.forename: Brian
authors.initials: B
authors.lastname: Kim
authors.forename: Paul W
authors.initials: PW
authors.lastname: Sternberg
authors.forename: Elissa A
authors.initials: EA
authors.lastname: Hallem
mesh_terms: D000093:Acetoin / Q000494:pharmacology; D000447:Aldehydes / Q000494:pharmacology; D000818:Animals; D001522:Behavior, Animal / Q000187:drug effects / Q000502:physiology; D017610:Calcium Compounds / Q000494:pharmacology; D002245:Carbon Dioxide / Q000494:pharmacology; D002633:Chemotaxis / Q000187:drug effects; D002722:Chlorobenzenes / Q000494:pharmacology; D003408:Cresols / Q000494:pharmacology; D000081005:Cyclohexane Monoterpenes; D049851:Gastropoda / Q000469:parasitology*; D006135:Gryllidae / Q000469:parasitology*; D006790:Host-Parasite Interactions / Q000502:physiology*; D039821:Monoterpenes / Q000494:pharmacology; D009348:Nematoda / Q000472:pathogenicity / Q000502:physiology*; D009349:Nematode Infections / Q000503:physiopathology*; D009812:Odorants; D010087:Oxides / Q000494:pharmacology; D012903:Smell / Q000502:physiology*; D012972:Sodium Hydroxide / Q000494:pharmacology; D014774:Virulence
chemical_list: D000447:Aldehydes; D017610:Calcium Compounds; D002722:Chlorobenzenes; D003408:Cresols; D000081005:Cyclohexane Monoterpenes; D039821:Monoterpenes; D010087:Oxides; D002245:Carbon Dioxide; C032538:4-cresol; C004569:soda lime; C018669:gamma-terpinene; D012972:Sodium Hydroxide; C010463:n-hexanal; D000093:Acetoin; C018511:4-dichlorobenzene