Bulletin of Entomological Research (2010) 100, 735-740

J.A. Stenberg and P.A. Hambäck (2010)
Host species critical for offspring fitness and sex ratio for an oligophagous parasitoid: implications for host coexistence
Bulletin of Entomological Research 100 (6), 735-740
Abstract: In theory, inferior apparent competitors sharing a natural enemy with superior apparent competitors should be excluded in the absence of stabilising factors. Nevertheless, plentiful examples of coexisting apparent competitors exist. In this paper, we show that parasitoid resource competition within hosts affects both parasitoid sex ratio and female body size, with implication for population growth and apparent competition between the two closely related hosts experiencing a strong asymmetry in their interaction. While the superior competitor delivers parasitoids with higher fitness to the shared parasitoid pool, the inferior competitor delivers a higher proportion of female parasitoids. Hence, the inferior host experience an inflow of fit parasitoids from the superior competitor, which should increase the risk of exclusion, but also an outflow of parasitoid females, which should reduce the risk of exclusion and increase stability. We conclude that differential outcomes of parasitoid resource competition in different host species may have profound effects on shared parasitoid populations and should be included in future studies of apparent competition between hosts.
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Link to article at publishers website
Database assignments for author(s): Johan A. Stenberg, Peter A. Hambäck

Research topic(s) for pests/diseases/weeds:
biocontrol - natural enemies
Research topic(s) for beneficials or antagonists:
environment/habitat manipulation

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Pest and/or beneficial records:

Beneficial	Pest/Disease/Weed	Crop/Product	Country	Quarant.
Neogalerucella calmariensis (weed bioagent)
Asecodes (genus - parasitoids)