Bulletin of Entomological Research (2010) 100, 255-261

V. Caron, J.H. Myers and D.R. Gillespie (2010)
The failure to discriminate: superparasitism of Trichoplusia ni Hübner by a generalist tachinid parasitoid
Bulletin of Entomological Research 100 (3), 255-261
Abstract: Parasitoids are dependent on their hosts, which provide all of the resources for larval development. Parasitoid fitness, therefore, is directly related to the host quality, as determined by host size, age and health (e.g. parasitisation status); and this can only be assessed by the female parasitoid during host selection. Most studies of parasitoid-host interactions have focused on hymenopteran parasitoids rather than dipterans that are believed to be less discriminating during host selection. We assessed the impact of host quality and superparasitism on parasitoid fitness in Compsilura concinnata Meigen, a gregarious tachinid dipteran parasitoid, and its lepidopteran host the cabbage looper, Trichoplusia ni Hübner.
Female C. concinnata parasitised all host stages of T. ni that were presented to them, but emergence rates were higher from older hosts. Females readily superparasitised hosts. The number of flies emerging was higher from hosts parasitised at later instars, and flies emerged earlier from heavily superparasitised hosts. Superparasitism decreased parasitoid pupal weight and development time, indicating intra-host competition between parasitoid larvae and skewed the parasitoid sex ratio in favour of males.
Host discrimination does not seem to be well developed in C. concinnata. Hosts are superparasitised despite the effects of superparasitism on offspring and sex ratio. This could be due to the wide host range of C. concinnata; avoiding high superparasitism could occur naturally due to host switching and, therefore, developing host discrimination mechanisms for one host species may not be crucial.
(The abstract is excluded from the Creative Commons licence and has been copied with permission by the publisher.)
Link to article at publishers website
Database assignments for author(s): Valerie Caron, Judith H. Myers, David R. Gillespie

Research topic(s) for pests/diseases/weeds:
biocontrol - natural enemies
Research topic(s) for beneficials or antagonists:
general biology - morphology - evolution

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Pest and/or beneficial records:

Beneficial	Pest/Disease/Weed	Crop/Product	Country	Quarant.
	Trichoplusia ni
Compsilura concinnata (parasitoid)	Trichoplusia ni