Triinu Mänd until 2008.
Size-dependent predation risk in tree-feeding insects with different colouration strategies: a field experiment
Article first published online: 1 JUN 2009
© 2009 The Authors. Journal compilation © 2009 British Ecological Society
Journal of Animal Ecology
Volume 78, Issue 5, pages 973–980, September 2009
How to Cite
Remmel, T. and Tammaru, T. (2009), Size-dependent predation risk in tree-feeding insects with different colouration strategies: a field experiment. Journal of Animal Ecology, 78: 973–980. doi: 10.1111/j.1365-2656.2009.01566.x
- Issue published online: 29 JUL 2009
- Article first published online: 1 JUN 2009
- Received 21 December 2008; accepted 22 April 2009 Handling Editor: Rob Knell
- artificial prey;
- body size;
- life history;
- top–down effects
1. Body size is positively correlated with fecundity in various animals, but the factors that counterbalance the resulting selection pressure towards large size are difficult to establish. Positively size-dependent predation risk has been proposed as a selective factor potentially capable of balancing the fecundity advantage of large size.
2. To construct optimality models of insect body size, realistic estimates of size-dependent predation rates are necessary. Moreover, prey traits such as colouration should be considered, as they may substantially alter the relationship between body size and mortality risk.
3. To quantify mortality patterns, we conducted field experiments in which we exposed cryptic and conspicuous artificial larvae of different sizes to bird predators, and recorded the incidence of bird attacks.
4. The average daily mortality rate was estimated to vary between 4% and 10%. In both cryptic and conspicuous larvae, predation risk increased with prey size, but the increase tended to be steeper in the conspicuous group. No main effect of colour type was found. All the quantitative relationships were reasonably consistent across replicates.
5. Our results suggest that the size dependence of mortality risk in insect prey is primarily determined by the probability of being detected by a predator rather than by a size-dependent warning effect associated with conspicuous colouration. Our results therefore imply that warningly coloured insects do not necessarily benefit more than the cryptic species from large body size, as has been previously suggested.