title: Development of a solitary koinobiont hyperparasitoid in different instars of its primary and secondary hosts.
abstract: Parasitoid wasps are excellent organisms for studying the allocation of host resources to different fitness functions such as adult body mass and development time. Koinobiont parasitoids attack hosts that continue feeding and growing during parasitism, whereas idiobiont parasitoids attack non-growing host stages or paralyzed hosts. Many adult female koinobionts attack a broad range of host stages and are therefore faced with a different set of dynamic challenges compared with idiobionts, where host resources are largely static. Thus far studies on solitary koinobionts have been almost exclusively based on primary parasitoids, yet it is known that many of these are in turn attacked by both koinobiont and idiobiont hyperparasitoids. Here we compare parasitism and development of a primary koinobiont hyperparasitoid, Mesochorus gemellus (Hymenoptera: Ichneumonidae) in larvae of the gregarious primary koinobiont parasitoid, Cotesia glomerata (Hymenoptera: Braconidae) developing in the secondary herbivore host, Pieris brassicae (Lepidoptera: Pieridae). As far as we know this is the first study to examine development of a solitary primary hyperparasitoid in different stages of its secondary herbivore host. Pieris brassicae caterpillars were parasitized as L1 by C. glomerata and then these parasitized caterpillars were presented in separate cohorts to M. gemellus as L3, L4 or L5 instar P. brassicae. Different instars of the secondary hosts were used as proxies for different developmental stages of the primary host, C. glomerata. Larvae of C. glomerata in L5 P. brassicae were significantly longer than those in L3 and L4 caterpillars. Irrespective of secondary host instar, every parasitoid cluster was hyperparasitized by M. gemellus but all only produced male progeny. Male development time decreased with host stage attacked, whereas adult male body mass did not, which shows that M. gemellus is able to optimally exploit older host larvae in terms of adult size despite their decreasing mass during the pupal stage. Across a range of cocoon masses, hyperparasitoid adult male body mass was approximately 84% as large as primary parasitoids, revealing that M. gemellus is almost as efficient at exploiting host resources as secondary (pupal) hyperparasitoids.
authors.affiliation: Department of Terrestrial Ecology, Netherlands Institute of Ecology (NIOO-KNAW), Droevendaalsesteeg 10, 6708 PB Wageningen, The Netherlands; Vrije Universeteit Amsterdam, Department of Ecological Sciences, Section Animal Ecology, De Boelelaan 1085, 1081 HV Amsterdam, The Netherlands. Electronic address: j.harvey@nioo.knaw.nl.
authors.forename: Jeffrey A
authors.initials: JA
authors.lastname: Harvey
authors.affiliation: Department of Terrestrial Ecology, Netherlands Institute of Ecology (NIOO-KNAW), Droevendaalsesteeg 10, 6708 PB Wageningen, The Netherlands.
authors.forename: Minghui
authors.initials: M
authors.lastname: Fei
authors.affiliation: Vrije Universeteit Amsterdam, Department of Ecological Sciences, Section Animal Ecology, De Boelelaan 1085, 1081 HV Amsterdam, The Netherlands.
authors.forename: Mark
authors.initials: M
authors.lastname: Lammers
authors.affiliation: Department of Terrestrial Ecology, Netherlands Institute of Ecology (NIOO-KNAW), Droevendaalsesteeg 10, 6708 PB Wageningen, The Netherlands.
authors.forename: Martine
authors.initials: M
authors.lastname: Kos
authors.affiliation: Department of Terrestrial Ecology, Netherlands Institute of Ecology (NIOO-KNAW), Droevendaalsesteeg 10, 6708 PB Wageningen, The Netherlands.
authors.forename: Feng
authors.initials: F
authors.lastname: Zhu
authors.affiliation: Department of Terrestrial Ecology, Netherlands Institute of Ecology (NIOO-KNAW), Droevendaalsesteeg 10, 6708 PB Wageningen, The Netherlands.
authors.forename: Robin
authors.initials: R
authors.lastname: Heinen
authors.affiliation: Laboratory of Entomology, Wageningen University, Droevendaalsesteeg 1, 6708 PB, The Netherlands.
authors.forename: Erik H
authors.initials: EH
authors.lastname: Poelman
authors.affiliation: Laboratory of Entomology, Wageningen University, Droevendaalsesteeg 1, 6708 PB, The Netherlands.
authors.forename: Rieta
authors.initials: R
authors.lastname: Gols
mesh_terms: D000818:Animals; D002080:Butterflies / Q000469:parasitology*; D005260:Female; D006790:Host-Parasite Interactions; D007814:Larva / Q000254:growth & development / Q000469:parasitology / Q000502:physiology; D008297:Male; D011679:Pupa / Q000254:growth & development / Q000469:parasitology / Q000502:physiology; D014863:Wasps / Q000254:growth & development* / Q000469:parasitology* / Q000502:physiology
keywords: Cotesia glomerata; Growth; Instar; Larva; Mesochorus gemellus; Pieris brassicae