Oecologia (2006) 148, 153-161

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Isabelle Amat, Marcela Castelo, Emmanuel Desouhant and Carlos Bernstein (2006)
The influence of temperature and host availability on the host exploitation strategies of sexual and asexual parasitic wasps of the same species
Oecologia 148 (1), 153-161
Abstract: In the hymenopteran parasitoid Venturia canescens, asexual (obligate thelytoky not induced by Wolbachia bacteria) and sexual (arrhenotokous) wasps coexist in field conditions despite the demographic cost incurred due to the production of males by sexual females. Arrhenotoky predominates in field conditions, whereas populations in indoor conditions (mills, granaries) are exclusively thelytokous. These differences in the relative abundance of the two modes of reproduction between environments suggest that the individuals of each reproductive mode may have developed strategies adapted to the conditions prevailing in each kind of habitat. The two environments contrast in temperature variability and in the spatial heterogeneity of host availability. In this study, we considered the combined effect of temperature and host availability on host patch exploitation by thelytokous and arrhenotokous V. canescens. As expected, arrhenotokous females were more sensitive to temperature changes. If the temperature decreased before foraging, they remained longer and exploited patches more thoroughly. This is consistent with the expected behaviour of parasitoids in response to signs of unfavourable conditions that entail increasing risk of time limitation or a reduced probability of attaining further patches. Both arrhenotokous and thelytokous females increased patch exploitation with host availability. However, unexpectedly, we found no difference in the way the two types of wasp responded to differences in host availability. Differences in the strategies adopted under different environmental conditions may indicate divergence of niche-specific life history traits between the two modes of reproduction. Niche displacement may partly account for the coexistence of these two modes of reproduction at a geographical scale.
(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): Emmanuel Desouhant

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


Pest and/or beneficial records:

Beneficial Pest/Disease/Weed Crop/Product Country Quarant.


Venturia canescens (parasitoid)