Patch Experience Changes Host Acceptance of the Aphid Parasitoid Aphidius ervi.

Lanteigne, M.-E., Brodeur, J., Jenni, S., and Boivin, G. (2015). "Patch Experience Changes Host Acceptance of the Aphid Parasitoid Aphidius ervi.", Journal of Insect Behavior. doi : 10.1007/s10905-015-9515-3  Access to full text

Abstract

We investigated patch quality assessment by the parasitoid Aphidius ervi Haliday (Hymenoptera: Braconidae) when exploiting colonies of the lettuce aphid Nasonovia ribisnigri Mosley (Hemiptera: Aphididae). Three host patches of different qualities were sequentially offered to a naïve female parasitoid. High quality patches (HQ) consisted of 20 N. ribisnigri reared on susceptible lettuce; low quality patches (LQ) consisted of 20 N. ribisnigri reared on partially resistant lettuce and mixed quality patches (MQ) consisted of equal numbers (10) of aphids reared on both lettuce types. Parasitized aphids were reared until parasitoid emergence; number of mummies and sex ratio were noted. On the first host patch encountered, the mean number of A. ervi mummies produced was significantly higher for HQ host patches (X ± SD; 7.1 ± 5.0) than for LQ host patches (3.8 ± 4.5). This suggests that female A. ervi do not need prior experience to assess patch quality; females probably using an innate estimate of patch quality when encountering a first host patch. This initial patch quality assessment can be modified with experience. When females encountered a MQ patch, they kept their exploitation level constant on the following patch, whatever its quality. Females increased their level of host acceptance on the third patch when three LQ patches were offered successively; accepting low-quality hosts could be preferable when better hosts are not currently available in the habitat. These results suggest that A. ervi females behave in a manner consistent with a Bayesian updating process when foraging for hosts.

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