Density-dependent allometric functional response models

Functional response models describe the relationship between predators and the rate at which prey are consumed. Traditional models are based on the density of prey and predators. More recently, the role of variables such as predator and prey size have received increased attention. This study presents several new modifications of existing functional response equations that incorporate predator size as a factor affecting capture rate and/or handling time. These models were tested on an experimental system in which we used several aquatic nepomorphan (Hemiptera: Heteroptera) predators of mosquito larvae. The models that best fitted our data were modified Beddington–DeAngelis and Hassell–Varley models in which predator size affected the handling time. Models in which predator size affected capture rates performed better than models without a predator size effect. This suggests that capture rates are also affected by predator size. This study shows that predator size is an important variable in functional response models, particularly when the size variation among predators is relatively large.