title: Habitat complexity reduces parasitoid foraging efficiency, but does not prevent orientation towards learned host plant odours.
abstract: It is well known that many parasitic wasps use herbivore-induced plant odours (HIPVs) to locate their inconspicuous host insects, and are often able to distinguish between slight differences in plant odour composition. However, few studies have examined parasitoid foraging behaviour under (semi-)field conditions. In nature, food plants of parasitoid hosts are often embedded in non-host-plant assemblages that confer both structural and chemical complexity. By releasing both naïve and experienced Cotesia glomerata females in outdoor tents, we studied how natural vegetation surrounding Pieris brassicae-infested Sinapis arvensis and Barbarea vulgaris plants influences their foraging efficiency as well as their ability to specifically orient towards the HIPVs of the host plant species on which they previously had a positive oviposition experience. Natural background vegetation reduced the host-encounter rate of naïve C. glomerata females by 47 %. While associative learning of host plant HIPVs 1 day prior to foraging caused a 28 % increase in the overall foraging efficiency of C. glomerata, it did not reduce the negative influence of natural background vegetation. At the same time, however, females foraging in natural vegetation attacked more host patches on host-plant species on which they previously had a positive oviposition experience. We conclude that, even though the presence of natural vegetation reduces the foraging efficiency of C. glomerata, it does not prevent experienced female wasps from specifically orienting towards the host-plant species from which they had learned the HIPVs.
authors.affiliation: Population and Evolutionary Ecology Group, University of Bremen, Bremen, Germany. marjolein.kruidhof@wur.nl.|Department of Terrestrial Ecology, Netherlands Institute of Ecology (NIOO-KNAW), Wageningen, The Netherlands. marjolein.kruidhof@wur.nl.|Wageningen UR Greenhouse Horticulture, Bleiswijk, The Netherlands. marjolein.kruidhof@wur.nl.
authors.forename: H M
authors.initials: HM
authors.lastname: Kruidhof
authors.affiliation: Population and Evolutionary Ecology Group, University of Bremen, Bremen, Germany.|Department of Terrestrial Ecology, Netherlands Institute of Ecology (NIOO-KNAW), Wageningen, The Netherlands.
authors.forename: A L
authors.initials: AL
authors.lastname: Roberts
authors.affiliation: Department of Terrestrial Ecology, Netherlands Institute of Ecology (NIOO-KNAW), Wageningen, The Netherlands.|Laboratory of Applied Entomology, Nagoya University, Nagoya, Japan.
authors.forename: P
authors.initials: P
authors.lastname: Magdaraog
authors.affiliation: Department of Terrestrial Ecology, Netherlands Institute of Ecology (NIOO-KNAW), Wageningen, The Netherlands.
authors.forename: D
authors.initials: D
authors.lastname: Muñoz
authors.affiliation: Laboratory of Entomology, Wageningen University, Wageningen, The Netherlands.
authors.forename: R
authors.initials: R
authors.lastname: Gols
authors.affiliation: Department of Terrestrial Ecology, Netherlands Institute of Ecology (NIOO-KNAW), Wageningen, The Netherlands.|Laboratory of Entomology, Wageningen University, Wageningen, The Netherlands.
authors.forename: L E M
authors.initials: LE
authors.lastname: Vet
authors.affiliation: Population and Evolutionary Ecology Group, University of Bremen, Bremen, Germany.
authors.forename: T S
authors.initials: TS
authors.lastname: Hoffmeister
authors.affiliation: Department of Terrestrial Ecology, Netherlands Institute of Ecology (NIOO-KNAW), Wageningen, The Netherlands.
authors.forename: J A
authors.initials: JA
authors.lastname: Harvey
mesh_terms: D000818:Animals; D031216:Barbarea / Q000737:chemistry; D002080:Butterflies / Q000469:parasitology* / Q000502:physiology; D017753:Ecosystem; D005247:Feeding Behavior; D005260:Female; D060434:Herbivory; D006790:Host-Parasite Interactions; D007814:Larva / Q000469:parasitology / Q000502:physiology; D009812:Odorants; D010058:Oviposition; D031226:Sinapis / Q000737:chemistry; D014863:Wasps / Q000502:physiology*
keywords: Cotesia glomerata; Host location; Learning; Pieris brassicae; Semi-field study