Submitted to: Comparative Biochemistry and Physiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/3/2003
Publication Date: 5/28/2003
Citation: NELSON,D.R., CHARLET,L.D., CUTICULAR HYDROCARBONS OF THE SUNFLOWER BEETLE, ZYGOGRAMMA EXCLAMATIONIS, COMPARATIVE BIOCHEMISTRY AND PHYSIOLOGY, Part B 135(2):273-284, 2003. Interpretive Summary: The cuticular surface lipids of insects function in many essential ways for the well-being of the insect, e.g., prevent water loss, reflect sunlight, and contain recognition semiochemicals for reproduction and detection by parasitoids and predators. Hydrocarbons are frequently a major component of the surface lipids. These hydrocarbons are usually methyl-branched alkanes and have enough specificity to species that they can be used for taxonomic purposes. The sunflower beetle adults, larvae and eggs had hydrocarbons as the major components of their surface lipids. The major hydrocarbon components had multiple methyl branches, the greatest number of methyl-branched alkanes found in the eggs and slightly less in the female indicating a possible role in reproduction. The species causing the greatest mortality in sunflower beetles is the parasitic fly, Myiopharus macellus, which parasitizes sunflower beetle larvae. The role of these highly methyl-branched surface lipids in this parasitization remains to be characterized.
Technical Abstract: Hydrocarbons were the major lipid class on the cuticular surface of adults, nymphs, and eggs of the sunflower beetle, Zygogramma exclamationis, characterized by gas chromatography-mass spectrometry. Minor amounts of wax ester from 40 to 48 carbon atoms in size were only detected in larvae. The hydrocarbons ranged in size from 23 carbons (tricosene) to 56 carbons (trimethyltripentacontane) and were largely methylalkanes. The major component from females was 13,17,21-trimethylnonatriacontane (19%) and from larvae was n-nonacosane (17%). Males had 11,15- and 9,15-dimethylheptacosane (11%) and 13,17,21-trimethylnonatriacontane (11%) as the major components. In a sample of eggs, 13,17,21-nonatriacontane (16%) was the major component which was approximately 3 to 4-fold greater than the next most abundant hydrocarbons, dimethylheptacosanes, 2-methyloctacosane, methylnonacosanes, dimethyl- and trimethylheptatriacontanes and dimethylnonatriacontanes.