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Psyche
Volume 2012, Article ID 345932, 7 pages
http://dx.doi.org/10.1155/2012/345932
Research Article

Herbivore Larval Development at Low Springtime Temperatures: The Importance of Short Periods of Heating in the Field

1Institute of Ecology and Evolution, University of Bern, Baltzerstrasse 6, 3012 Bern, Switzerland
2Department of Animal Ecology and Tropical Biology, University of Würzburg, Am Hubland, 97074 Würzburg, Germany

Received 4 July 2011; Revised 14 October 2011; Accepted 29 October 2011

Academic Editor: Panagiotis Milonas

Copyright © 2012 Esther Müller and Elisabeth Obermaier. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Temperature has been shown to play an important role in the life cycles of insects. Early season feeders in Palaearctic regions profit by the high nutritional quality of their host plants early in the year, but face the problem of having to develop at low average springtime temperatures. This study examines the influence of short periods of heating in the field on larval development and on mortality with the model system Galeruca tanaceti L. (Coleoptera: Chrysomelidae), an early season feeder, that hatches at low springtime temperatures. Field and laboratory experiments under different constant and variable temperature regimes were performed. While in the field, the average daily temperature was close to the lower developmental threshold of the species of 10.9°C; maximum temperatures of above 30°C were sometimes reached. Larvae developed significantly faster, and pupae were heavier, in the field and in an assay with short periods of heating than at the same average temperature under constant conditions in the laboratory. We conclude that larvae profit substantially from short periods of heating and temperature variation in the field and that intervals of high temperature enable insect survival and exploitation of nutrient-rich food resources at early times in the season.