Condition-dependent foraging in the wolf spider Hogna baltimoriana

Abstract

Spiders are major predators of terrestrial arthropods, so understanding the underlying drivers of spider foraging is crucial for understanding how energy and nutrients pass through terrestrial food webs. We tested predictions made by allometric and optimal foraging theory using the wolf spider Hogna baltimoriana and grasshopper prey as a model (Caelifera). Allometric foraging theory predicts that functional response parameters will be dependent on body size, whereas optimal foraging theory asserts the importance of energetic state in determining foraging behaviors. We found that space clearance rate (type II functional response parameter a) was negatively related to the ratio of abdomen width to carapace width (a measure of energetic state) but not to body mass or carapace width. Thus, a key factor in determining the strength of foraging interactions in spiders may be recent energy intake that determines the current body condition of foragers.