The Swedish Natural Science Research Council and The Swedish Research Council for Environment, Agricultural Sciences and Spatial Planning.
Small-scale resource tracking in a population of a long-lived insect
Article first published online: 24 SEP 2012
© 2012 The Authors. Ecology and Evolution published by Blackwell Publishing Ltd.
This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.
Ecology and Evolution
Volume 2, Issue 11, pages 2659–2668, November 2012
How to Cite
Ecology and Evolution 2012; 2(11): 2659–2668
- Issue published online: 8 NOV 2012
- Article first published online: 24 SEP 2012
- Manuscript Accepted: 20 AUG 2012
- Manuscript Revised: 15 AUG 2012
- Manuscript Received: 10 APR 2012
- Swedish Natural Science Research Council
- Swedish Research Council for Environment, Agricultural Sciences and Spatial Planning
- Flowering pattern;
- prolonged diapause;
- resource exploitation;
- small scale patchiness;
- white swallow-wort
How plant-feeding insects distribute themselves and utilize their host plant resources is still poorly understood. Several processes may be involved, and their relative roles may vary with the spatial scale considered. Herein, we investigate small-scale patterns, namely how population density of a gall midge is affected by individual growth form, phenology, and microsite characteristics of its herb host. The long-lived plant individuals vary much with regard to number of shoots, flower abundance, and flowering phenology. This variation is connected to site characteristics, primarily the degree of sun exposure. The monophagous insect galls the flowers of the host plant – an easily defined food resource. It is a poor disperser, but very long-lived; diapausing larvae can stay in the soil for many years. Galls were censused on individual plants during 5 years; from a peak to a low in gall population density. Only a very small fraction of the flowers produced (<0.5%) were galled even in the peak year. Nevertheless, most plant individuals had galls at least 1 year. In a stepwise multiple regression, plant size (number of shoots) was found to be the most important predictor of gall density (galls/flower). However, gall density decreased more than one order of magnitude over the plant size range observed. There was also a weak effect of plant phenology. Early flowering plants had lower gall densities than those starting later. Sun exposure had no direct effect on gall density, but a path analysis revealed indirect effects via the timing of flowering. Gall population change was highly synchronous in different parts of the study area with no significant decrease in synchrony with distance.