Ecological Entomology (2001) 26, 271-280

Y. Outreman, A. Le Ralec, E. Wajnberg and J.S. Pierre (2001)
Can imperfect host discrimination explain partial patch exploitation in parasitoids?
Ecological Entomology 26 (3), 271-280
Abstract: 1. Host discrimination by Aphidius rhopalosiphi (De Stefani Perez) (Hymenoptera: Braconidae) was first studied on the grain aphid Sitobion avenae (Fabricius) (Homoptera: Aphididae). Females tended to avoid oviposition in hosts parasitised 3 h earlier. No evidence of host discrimination ability on freshly parasitised hosts was suggested, however, and ovipositional experience had no effect on host discrimination.
2. The effects of host discrimination ability on the exploitation strategy of patches containing different proportions of unparasitised hosts and hosts parasitised for 3 h were studied. Females spent less time on patches with a higher proportion of parasitised hosts, reflecting the females' ability to perceive the potential profitability of the patch. This ability may be based on the nature of the hosts encountered (unparasitised or parasitised).
3. Incomplete exploitation of unparasitised hosts was also observed. It seems that this partial exploitation is related to the inability of A. rhopalosiphi to recognise freshly parasitised hosts. As a female may experience a risk of self-superparasitism during patch depletion, this could promote early departure from incompletely exploited patches.
4. The effect of previous experience on the patch exploitation strategy was also assessed. Females were tested twice on two patches of the same quality. Results suggested that the experience acquired during a previous visit led the females to leave the patch sooner and to lay fewer eggs in parasitised hosts.
5. Patch exploitation strategy may therefore be the result of different factors such as host discrimination and experience. The evolutionary consequences of the results are discussed.
(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): Yannick Outreman

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

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Pest and/or beneficial records:

Beneficial	Pest/Disease/Weed	Crop/Product	Country	Quarant.
	Sitobion avenae
Aphidius rhopalosiphi (parasitoid)	Sitobion avenae