Monday, December 10, 2007 - 10:29 AM

Predator diversity influences the ecology of fear in a collard community

Shawn A Steffan, and William E Snyder, Washington State University, Entomology, FSHN 166, PO Box 646382, Pullman, WA

Predators may have lethal and/or non-lethal interactions with their prey, and the effects of such interactions may cascade to the resource base on which the prey feed. Recent findings suggest that non-lethal predator effects are common and can be as important as lethal interactions. Predator effects can also be significantly influenced by the diversity of predators and/or prey. While it has been documented that increasing predator diversity may improve herbivore suppression, it remains to be resolved whether increasing predator diversity translates into greater non-lethal effects on prey or the base of the food chain. Our work examined predator-prey interactions within the diverse community of predators attacking larval diamondback moths (Plutella xylostella L.) on collard plants (Brassica oleracea L.). We partitioned predator effects into lethal and non-lethal components and examined how the effects of predator species richness varied within and across these two components. A pool of five predator species was used to create low and high species richness treatments, and responses were measured in terms of direct predator effects on herbivores (density reductions and behavioral trait-changes) as well as the indirect effects of predators on plants (changes in plant biomass). We found positive diversity effects for predators on prey and a significant indirect effect of predators on plants. Results will be discussed in the context of biodiversity and fear ecology.

Species 1: Lepidoptera Plutellidae Plutella xylostella (diamondback moth)
Species 2: Hymenoptera Ichneumonidae Diadegma insulare
Species 3: Hemiptera Nabidae Nabis