title: Maize landraces recruit egg and larval parasitoids in response to egg deposition by a herbivore.
abstract: Natural enemies respond to herbivore-induced plant volatiles (HIPVs), but an often overlooked aspect is that there may be genotypic variation in these 'indirect' plant defence traits within plant species. We found that egg deposition by stemborer moths (Chilo partellus) on maize landrace varieties caused emission of HIPVs that attract parasitic wasps. Notably, however, the oviposition-induced release of parasitoid attractants was completely absent in commercial hybrid maize varieties. In the landraces, not only were egg parasitoids (Trichogramma bournieri) attracted but also larval parasitoids (Cotesia sesamiae). This implies a sophisticated defence strategy whereby parasitoids are recruited in anticipation of egg hatching. The effect was systemic and caused by an elicitor, which could be extracted from egg materials associated with attachment to leaves. Our findings suggest that indirect plant defence traits may have become lost during crop breeding and could be valuable in new resistance breeding for sustainable agriculture.
authors.affiliation: Habitat Management Programme, International Centre of Insect Physiology and Ecology, PO Box 30, Mbita Point, Kenya.
authors.forename: Amanuel
authors.initials: A
authors.lastname: Tamiru
authors.forename: Toby J A
authors.initials: TJ
authors.lastname: Bruce
authors.forename: Christine M
authors.initials: CM
authors.lastname: Woodcock
authors.forename: John C
authors.initials: JC
authors.lastname: Caulfield
authors.forename: Charles A O
authors.initials: CA
authors.lastname: Midega
authors.forename: Callistus K P O
authors.initials: CK
authors.lastname: Ogol
authors.forename: Patrick
authors.initials: P
authors.lastname: Mayon
authors.forename: Michael A
authors.initials: MA
authors.lastname: Birkett
authors.forename: John A
authors.initials: JA
authors.lastname: Pickett
authors.forename: Zeyaur R
authors.initials: ZR
authors.lastname: Khan
mesh_terms: D000475:Alkenes / Q000378:metabolism; D000818:Animals; D001522:Behavior, Animal; D002678:Chimera; D004463:Ecology; D060434:Herbivory; D006790:Host-Parasite Interactions; D007814:Larva / Q000469:parasitology; D009036:Moths; D010058:Oviposition; D000081223:Polycyclic Sesquiterpenes; D012717:Sesquiterpenes / Q000378:metabolism; D055549:Volatile Organic Compounds / Q000378:metabolism*; D014863:Wasps / Q000502:physiology*; D003313:Zea mays / Q000235:genetics* / Q000469:parasitology*; D013729:Terpenes
chemical_list: D000475:Alkenes; D000081223:Polycyclic Sesquiterpenes; D012717:Sesquiterpenes; D055549:Volatile Organic Compounds; C411254:4,8-dimethyl-1,3,7-nonatriene; D013729:Terpenes; C024714:caryophyllene