TY - JOUR
T1 - Learning by the parasitoid wasp, Aphidius ervi (Hymenoptera
T2 - Braconidae), alters individual fixed preferences for pea aphid color morphs
AU - Langley, Shaun A.
AU - Tilmon, Kelley J.
AU - Cardinale, Bradley J.
AU - Ives, Anthony R.
N1 - Funding Information:
Acknowledgements We would like to thank especially Bret Larget for statistical advice, and Mike Brewer, Takuji Noma, Matt Kaiser, and two anonymous reviewers for comments on the manuscript. We thank Dwight Mueller and the staff of the Arlington Agricultural Research Station for help and support during the field sampling. This project was supported by a Hill-dale Grant for Undergraduate Research from the UW-Madison, a Eugene Jorgens Undergraduate Research Award from the Department of Zoology, University of Wisconsin, Madison, and NSF grants to A. R. I. The experiments presented here comply with all current laws of the United States of America.
PY - 2006/11
Y1 - 2006/11
N2 - Learning, defined as changes in behavior that occur due to past experience, has been well doc- umented for nearly 20 species of hymenopterous par- asitoids. Few studies, however, have explored the influence of learning on population-level patterns of host use by parasitoids in field populations. Our study explores learning in the parasitoid Aphidius ervi Hal- iday that attacks pea aphids, Acyrthosiphon pisum (Harris). We used a sequence of laboratory experi- ments to investigate whether there is a learned com- ponent in the selection of red or green aphid color morphs. We then used the results of these experiments to parameterize a model that examines whether learned behaviors can explain the changes in the rates of parasitism observed in field populations in South- central Wisconsin, USA. In the first of two experiments, we measured the sequence of host choice by A. ervi on pea aphid color morphs and analyzed this se- quence for patterns in biased host selection. Parasitoids exhibited an inherent preference for green aphid morphs, but this preference was malleable; initial encounters with red aphids led to a greater chance of subsequent orientation towards red aphids than pre- dicted by chance. In a second experiment, we found no evidence that parasitoids specialize on red or green morphs; for the same parasitoids tested in trials sepa- rated by 2 h, color preference in the first trial did not predict color preference in the second, as would be expected if they differed in fixed preferences or exhibited long-term (> 2 h) learning. Using data from the two experiments, we parameterized a population dynamics model and found that learning of the mag- nitude observed in our experiments leads to biased parasitism towards the most common color morph. This bias is sufficient to explain changes in the ratio of aphid color morphs observed in field sites over multi- ple years. Our study suggests that for even relatively simple organisms, learned behaviors may be important for explaining the population dynamics of their hosts.
AB - Learning, defined as changes in behavior that occur due to past experience, has been well doc- umented for nearly 20 species of hymenopterous par- asitoids. Few studies, however, have explored the influence of learning on population-level patterns of host use by parasitoids in field populations. Our study explores learning in the parasitoid Aphidius ervi Hal- iday that attacks pea aphids, Acyrthosiphon pisum (Harris). We used a sequence of laboratory experi- ments to investigate whether there is a learned com- ponent in the selection of red or green aphid color morphs. We then used the results of these experiments to parameterize a model that examines whether learned behaviors can explain the changes in the rates of parasitism observed in field populations in South- central Wisconsin, USA. In the first of two experiments, we measured the sequence of host choice by A. ervi on pea aphid color morphs and analyzed this se- quence for patterns in biased host selection. Parasitoids exhibited an inherent preference for green aphid morphs, but this preference was malleable; initial encounters with red aphids led to a greater chance of subsequent orientation towards red aphids than pre- dicted by chance. In a second experiment, we found no evidence that parasitoids specialize on red or green morphs; for the same parasitoids tested in trials sepa- rated by 2 h, color preference in the first trial did not predict color preference in the second, as would be expected if they differed in fixed preferences or exhibited long-term (> 2 h) learning. Using data from the two experiments, we parameterized a population dynamics model and found that learning of the mag- nitude observed in our experiments leads to biased parasitism towards the most common color morph. This bias is sufficient to explain changes in the ratio of aphid color morphs observed in field sites over multi- ple years. Our study suggests that for even relatively simple organisms, learned behaviors may be important for explaining the population dynamics of their hosts.
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U2 - 10.1007/s00442-006-0486-0
DO - 10.1007/s00442-006-0486-0
M3 - Article
C2 - 16858585
AN - SCOPUS:35148833325
VL - 150
SP - 172
EP - 179
JO - Oecologia
JF - Oecologia
SN - 0029-8519
IS - 1
ER -