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Harvard Forest REU Symposium Abstract 2009
- Title: Nectar production and anthocyanins in Sarracenia purpurea and their resulting effect on prey capture
- Author: Katherine F Bennett (J R Briggs Elementary School)
- Abstract:
The northern pitcher plant, Sarracenia purpurea, possesses extrafloral nectaries that secrete nectar to attract potential prey. They also display intricate red and green patterns that have been hypothesized to play a role in attracting insects. However, our previous results show that insects are attracted by the presence of sugar, not coloration. In fact, prey capture decreases slightly as anthocyanins (red pigmentation) increase. Therefore, we hypothesized a correlation between increased anthocyanin production and decreased nectar production. We conducted our experiments at Tom Swamp between July 1 and August 31, 2009. Fifty pitchers with an incremental range of red patterning density were chosen and analyzed for prey capture. Nectar was sampled twice on these plants, using 1-cm2 filter-paper wicks on six locations on the pitcher. Sugars from the wicks were redissolved, extracted, and analyzed colorimetrically. We predict that wicks from pitchers with more red color will yield less sugar than those with more green, therefore suggesting less nectar rewards to potential prey. Further, we conducted a series of prey capture experiments using four sets of 20 pitcher mimics: 50 ml. centrifuge tubes painted to resemble live pitchers, one set all red, one all green, and two sets with alternating red and green stripes. Sugar solution was placed on half of the pitcher mimics, either randomly on the surface, on red veins, or on green inter-vein spaces, to test which mimics would attract more prey. Half of each set of mimics contained an insect drowning agent of strained fluid from live pitcher plants to determine if the fragrance of decomposing prey also plays a role in the attraction of prey. The mimics were set out in the same bog and prey was analyzed to determine joint relationships of color, nectar, and fragrance and prey capture rates.
- Research Category:
