Population Ecology (2007) 49, 347-355
Matthew Meisner, Jason P. Harmon and Anthony R. Ives (2007)
Presence of an unsuitable host diminishes the competitive superiority of an insect parasitoid: a distraction effect
Population Ecology 49 (4), 347-355
Abstract: Competitive interactions between parasitoid species are traditionally evaluated when they compete for a single host species. Yet, the presence of additional host species can alter competitive interactions, even if the host is unsuitable for parasitoid development. In alfalfa of the mid-western USA, a native parasitoid species, Praon pequodorum, was once a dominant natural enemy, but it has become rare since the introduction of another parasitoid, Aphidius ervi. Despite A. ervi's competitive superiority for their most common host, the pea aphid Acyrthosiphon pisum, P. pequodorum still persists at low densities. We performed a suite of laboratory and field studies to determine if the presence of an alternative host, the spotted alfalfa aphid Therioaphis maculata, may mitigate A. ervi's competitive superiority and facilitate P. pequodorum's persistence. We show that spotted alfalfa aphids reduce the foraging efficiency of both parasitoid species for pea aphids, despite spotted alfalfa aphids being an unsuitable host. This decrease in efficiency, however, was not symmetrical; the presence of spotted alfalfa aphids had a greater detrimental effect on A. ervi foraging for pea aphids. This might facilitate the persistence of the competitively inferior P. pequodorum. Our study suggests that indirect effects generated by the presence of alternative hosts are important for understanding parasitoid-host dynamics and overall insect community structure.
(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): Jason P. Harmon, Anthony R. Ives
Research topic(s) for pests/diseases/weeds:
biocontrol - natural enemies
environment - cropping system/rotation
Research topic(s) for beneficials or antagonists:
environment/habitat manipulation
