Effect of color, size, and density of Sarracenia purpurea on prey capture

Abstract

Our objective was to study physical characteristics of the purple pitcher plant (Sarracenia purpurea) in northern Michigan to determine an effect on the amount (biomass) and richness of insect prey capture. We examined pitcher density, amount of red venation, and pitcher size (length, mouth diameter, and keel width) of 40 pitchers. The catch contained individuals from eleven different insect Orders, the most abundant being Hymenoptera and Diptera. Higher species richness was positively correlated to high-density pitcher groups and mouth diameter. The highest density of pitchers in a plant was 38 pitchers, one of which had 4 different species inside. The highest species richness in a pitcher was 7 different species and the largest mouth diameter was approx. 35mm. Biomass was also positively correlated to mouth diameter, but not to density, pitcher length or keel width. Color showed to be insignificant in determining prey capture. Morphological variation may hold some responsibility in attracting insect prey, but future studies examining an exhaustive scope of pitcher physical traits and their cumulative effect may be valuable in finding the exact mechanism of prey capture.