Meeting Abstract
P1.68 Thursday, Jan. 3 Hide- and-seek among wolf spider and grasshoppers: applying ecology of fear to invertebrates JOERN,, A.; LAWS,, A.; GOMEZ,, J.E.**; Kansas State University, Manhattan; Kansas State University, Manhattan; Univ. of Puerto Rico, Humacao Campus, Humacao licaon_666@yahoo.com
The ecology of fear is used to describe the nonlethal interactions between predators and their prey. The theory predicts that predator presence can affect behavior, such as feeding of prey individuals. However, this theory has only been applied to mammalian species. We tested whether the ecology of fear could be used to predict interactions between invertebrate species. The theory was applied to grasshoppers (Acrididae) and spiders (Lycosidae), common predators of grasshoppers. Our study had three goals: (1) Determine variability in grasshopper and spider density among watersheds with different management regimes. (2) To determine if spider presence alters the spatial distribution of grasshoppers within sites, and (3) to determine if spider presence can affect grasshopper herbivory. Spider abundance and species composition were measured along with grasshopper density and vegetation biomass at nine sites at the Konza Prairie Biological Station LTER in Kansas. Both spider and grasshopper densities varied significantly among sites We did not observe relationship between vegetation biomass and spider (p value 0.991) or grasshopper density (p value 0.965). However, there was a negative relationship between grasshopper and spider densities among sites (p value 0.036). This suggests that biotic interactions between grasshoppers and spiders may be important to influencing grasshopper population dynamics. Grasshopper feeding was measured by setting up bioassays at three plots based on spider density. We observed that grasshopper herbivory decreased with spider density among plots. Within plots, the spatial distribution of feeding by grasshoppers was also influenced by spider density. These results supported predictions based on the ecology of fear.
