| Title: | Regulation of forest defoliating insects through small mammal predation: reconsidering the mechanisms |
| Author(s): | Kollberg I; Bylund H; Huitu O; Bjorkman C; |
| Address: | "Department of Ecology, Swedish University of Agricultural Sciences, Box 7044, 750 07, Uppsala, Sweden, ida.kollberg@slu.se" |
| DOI: | 10.1007/s00442-014-3080-x |
| ISSN/ISBN: | 1432-1939 (Electronic) 0029-8549 (Print) 0029-8549 (Linking) |
| Abstract: | "Population densities of forest defoliating insects may be regulated by small mammal predation on the pupae. When outbreaks do occur, they often coincide with warm, dry weather and at barren forest sites. A proposed reason for this is that weather and habitat affect small mammal population density (numerical response) and hence pupal predation. We propose an alternative explanation: weather and habitat affect small mammal feeding behaviour (functional response) and hence the outbreak risks of forest pest insects. We report results from laboratory and field-enclosure experiments estimating rates of pupal predation by bank voles (Myodes glareolus) on an outbreak insect, the European pine sawfly (Neodiprion sertifer), at different temperatures (15 and 20 degrees C), in different microhabitats (sheltered and non-sheltered), and with or without access to alternative food (sunflower seeds). We found that the probability of a single pupa being eaten at 20 degrees C was lower than at 15 degrees C (0.49 and 0.72, respectively). Pupal predation was higher in the sheltered microhabitat than in the open one, and the behaviour of the voles differed between microhabitats. More pupae were eaten in situ in the sheltered microhabitat whereas in the open area more pupae were removed and eaten elsewhere. Access to alternative food did not affect pupal predation. The results suggest that predation rates on pine sawfly pupae by voles are influenced by temperature- and habitat-induced variation in the physiology and behaviour of the predator, and not necessarily solely through effects on predator densities as previously proposed" |
| Keywords: | "Animals *Arvicolinae/physiology *Behavior, Animal Ecosystem *Environment *Feeding Behavior Forests Herbivory *Hymenoptera Mammals *Pinus Plant Leaves Population Density *Predatory Behavior Pupa Seasons Temperature Weather;" |
| Notes: | "MedlineKollberg, Ida Bylund, Helena Huitu, Otso Bjorkman, Christer eng Research Support, Non-U.S. Gov't Germany 2014/09/23 Oecologia. 2014 Dec; 176(4):975-83. doi: 10.1007/s00442-014-3080-x. Epub 2014 Sep 19" |
