Document: DAN-3-48-9

Sarmentosin sequestration by apollo butterflies in the Colorado alpine.

GARRIGAN, D.*

Pacific Lutheran University, Tacoma, WA 98447 USA ¹

Abstract:
Both the larval and adult stages of Apollo butterflies are aposematic and reportedly distasteful to predators. The Small Apollo (Parnassius phoebus) was recently shown to sequester a cyanoglucoside, sarmentosin, from its hostplant (Sedum stenopetalum) in Washington State, USA. Over the past three summers, I have investigated the chemical ecology of P. phoebus and its host, Yellow Stonecrop (S. lanceolatum), in the Rocky Mountains. In my study, Colorado P. phoebus sequestered significant amounts of sarmentosin from S. lanceolatum. Sarmentosin concentration of butterflies was one to two orders of magnitude greater than that of the plants. Male and female butterflies, however, did not differ significantly in the concentration of sarmentosin sequestered. Because sarmentosin is a nitrogenous defense, I have hypothesized that its production by plants should be limited by available nitrogen. Automobile emissions have resulted in increased rates of nitrogen deposition in the Front Range of the Rocky Mountains adjacent to Denver, Colorado. Plants and butterflies were sampled along the Colorado Front Range as well as across the Continental Divide in order to assess the effects of environmental pollution on the chemical interactions between insects and their hostplants. Curiously, both plants and insects from lower elevations (2435 m) contained more sarmentosin than those at higher elevations (3535 m) where greater nitrogen deposition is expected. It is not yet clear whether this >difference is due to differences in nitrogen deposition, nitrogen cycling, or the physiology of S. lanceolatum and P. phoebus.

Keywords: sequestration, chemical defense, pollution, nitrogen, Apollo butterflies, Parnassius, Sedum, sarmentosin

This abstract is being presented at: 3:30 PM in session:
HERBIVORE EFFECTS ON PLANTS