Intrinsic competition among solitary and gregarious endoparasitoid wasps and the phenomenon of ‘resource sharing’
Magdaraog, P.M. ; Harvey, J.A. ; Tanaka, T. ; Gols, R. - \ 2012
Ecological Entomology 37 (2012)1. - ISSN 0307-6946 - p. 65 - 74.
intraspecific larval competition - interspecific competition - meteorus-pulchricornis - developmental interactions - hymenoptera-braconidae - insect multiparasitism - microplitis-demolitor - copidosoma-floridanum - pseudaletia-separata - heliothis-virescens
1. Intrinsic competition was compared in three species of braconid wasps, the solitary Meteorus pulchricornis Wesmael, and the gregarious Cotesia kariyai (Watanabe) and Cotesia ruficrus Haliday in caterpillars of their common host, the armyworm Mythimna separata Walker. Competition was determined in pair-wise contests consisting of simultaneous and subsequent parasitisms at various time intervals between the first and second attacks (
Differing Success of Defense Strategies in Two Parasitoid Wasps in Protecting Their Pupae Against a Secondary Hyperparasitoid
Harvey, J.A. ; Gols, R. ; Tanaka, T. - \ 2011
Annals of the Entomological Society Of America 104 (2011)5. - ISSN 0013-8746 - p. 1005 - 1011.
cotesia-glomerata l. - meteorus-pulchricornis - behavioral manipulation - separata lepidoptera - pseudaletia-separata - insect parasitoids - host caterpillars - life-history - braconidae - hymenoptera
During their larval development, endoparasitoids are known to dispose of host resources in several different ways. Some parasitoid wasps consume most or all tissues of the host, whereas others consume a small fraction of host resources and either ensure that the host moves away from the pupation site or allow the host to remain close to the parasitoid cocoon(s). Using a single host species, Mythimna separata Walker (Lepidoptera: Noctuidae), this study compares the success of the two pupation strategies in the solitary parasitoids Microplitis sp. and Meteorus pulchricornis Wesmael (Hymenoptera: Braconidae) against attack from a secondary hyperparasitoid, Gelis agilis F. (Hymenoptera: Ichneumonidae). The caudal appendages of M. separata caterpillars parasitized by Microplitis sp. remain physically attached to parasitoid cocoons and the caterpillars behave aggressively when disturbed. However, after Me. pulchricornis larvae emerge from caterpillars of their host, M. separata, the parasitoid larvae pupate in cocoons that are suspended by a single thick thread that hangs 1–2 cm from under a leaf. In choice tests conducted in petri dishes, significantly fewer cocoons of Microplitis sp. attended by caterpillars than unattended cocoons were hyperparasitized by G. agilis. By contrast, Me. pulchricornis cocoons that were hanging from corn, Zea mays L., plants were hyperparasitized as frequently as those which were attached to leaves. We discuss the potentially different selection pressures generated among natural enemies such as predators and hyperparasitoids in determining optimal pupal defense strategies in primary parasitoids.
The ‘usurpation hypothesis’ revisited: dying caterpillar repels attack from a hyperparasitoid wasp
Harvey, J.A. ; Tanaka, T. ; Kruidhof, M. ; Vet, L.E.M. ; Gols, R. - \ 2011
Animal Behaviour 81 (2011)6. - ISSN 0003-3472 - p. 1281 - 1287.
cotesia-glomerata l. - host behavior - developmental strategies - hymenoptera-braconidae - apanteles-melanoscelus - southwestern virginia - pseudaletia-separata - manipulation - parasitoids - lepidoptera
It has been posited that some parasitoid wasps ‘usurp’ their dying hosts as ‘bodyguards’ to protect the vulnerable parasitoid cocoons against attack from natural enemies such as predators or hyperparasitoids. Thus far, however, the hypothesis has been supported only in studies with insect predators. Two factors may account for this: first, hyperparasitoids, being more specialized than predators, are probably less easily rebuffed by the presence of an attending caterpillar; second, the host cocoon is used for reproduction by hyperparasitoids, but not by predators. We compared the survival of a solitary primary parasitoid, Microplitis sp., and successful parasitism by a secondary hyperparasitoid, Gelis agilis, from parasitoid cocoons with and without the presence of an ‘attending’ larva of the host, the armyworm, Mythimna separata. Mature Microplitis sp. larvae always emerge through the same host segment, leaving the posterior segments paralysed and attached to cocoons and the anterior segments freely moving. When disturbed by G. agilis females, M. separata larvae exhibited aggressive behaviour that repeatedly drove off approaching hyperparasitoids. In choice and no-choice experiments performed at 24 h intervals over 96 h, G. agilis successfully parasitized cocoons without attending caterpillars, but few cocoons with attending caterpillars were ever parasitized. Choice experiments, in which G. agilis wasps were released onto corn plants containing 24 h-old parasitoid cocoons with and without attending caterpillars, produced similar results. We provide the first experimental evidence that a solitary parasitoid usurps the behaviour of its host over several days as a ‘bodyguard’ against hyperparasitoids