Evol Ecol Res 8: 703-715 (2006)     Full PDF if your library subscribes.

Thermal reaction norms for caterpillar growth depend on diet

Joel G. Kingsolver,* J. Gwen Shlichta,‡ Gregory J. Ragland and Katie R. Massie§

Department of Biology, University of North Carolina, Chapel Hill, NC 27599, USA

Author to whom all correspondence should be addressed.
e-mail: jgking@bio.unc.edu


Hypothesis: Interactions between diet and temperature affect reaction norms for growth rate in ectotherms.

Organisms: Full-sib families of the small cabbage white butterfly, Pieris rapae, derived from field populations near Seattle, WA, USA.

Methods: We used a split sib-family experimental design with two food treatments (collard leaves and artificial diet) and four test temperatures (11, 23, 35 and 40°C), and measured short-term growth rate (mass increase) of fourth-instar caterpillars. The data were analysed using mixed-model analysis of variance.

Results: Temperature, food type, family, and two- and three-way interactions all had significant effects on growth rate. The thermal sensitivity of growth rate was greater on collards than on the artificial diet; mean growth rate was greater on collards than on the artificial diet for temperatures from 11 to 35°C, but this effect was reversed at 40°C. Estimated broad-sense genetic variances were greater on collards than on the artificial diet; the genetic covariance of growth rate at 35 and 40°C was strongly positive on the artificial diet, but weak or negative on collard leaves.

Conclusions: Both the mean and genetic variation in thermal reaction norms for insect growth rate were influenced by food type in this system. Studies of the thermal sensitivity of growth and feeding that utilize artificial diets may not accurately reflect genetic variation or constraints on thermal reaction norms that may occur on natural food resources.

Keywords: diet, insect growth, phenotypic plasticity, Pieris rapae, reaction norm, temperature.

IF you are connected using the IP of a subscribing institution (library, laboratory, etc.)
or through its VPN.


        © 2006 Joel G. Kingsolver. All EER articles are copyrighted by their authors. All authors endorse, permit and license Evolutionary Ecology Ltd. to grant its subscribing institutions/libraries the copying privileges specified below without additional consideration or payment to them or to Evolutionary Ecology, Ltd. These endorsements, in writing, are on file in the office of Evolutionary Ecology, Ltd. Consult authors for permission to use any portion of their work in derivative works, compilations or to distribute their work in any commercial manner.

       Subscribing institutions/libraries may grant individuals the privilege of making a single copy of an EER article for non-commercial educational or non-commercial research purposes. Subscribing institutions/libraries may also use articles for non-commercial educational purposes by making any number of copies for course packs or course reserve collections. Subscribing institutions/libraries may also loan single copies of articles to non-commercial libraries for educational purposes.

       All copies of abstracts and articles must preserve their copyright notice without modification.