Meeting Abstract
Milkweed of the genus Asclepias are a group of plants that produce toxins to deter defoliation by herbivores. Despite this defense mechanism, there are many invertebrates that feed upon this group exclusively. Among those are two true bugs, a beetle, and the larvae of the Monarch butterfly. We are interested in the variation of macromolecules among Asclepias species and if these differences are reflected in the tissue of the herbivores that feed upon them. Asclepias viridis and A. asperula leaves were used to construct a lipid profile to analyze the assimilation of fatty acids by the Large Milkweed Bug (Oncopeltus fasciatus). We also profiled the tropical species, A. currisavica, for a more robust comparison of lipid profiles among species. Lipids were extracted from leaf samples and the tissue of the bug using a mixture of chloroform/methanol/water in a 4:2:1 ratio, converted to fatty acid methyl esters, and analyzed by Gas Chromatography-Mass Spectrometry. The fatty acid within milkweed that were found in highest abundance was palmitic acid (16:0) followed by stearic acid (18:0). These same fatty acids were found in the insect tissue, yet in different ratios. Additionally, smaller amounts of odd chain fatty acids, uncommonly found in biological systems, were present within the milkweed leaves. These data provide avenues for further study. These methods will be extended to the imperiled Monarch butterfly to better understand transfer of energetically important molecules from plant to herbivore.
