A comparative study of the phospholipids and fatty acids of some insects.
Phospholipids of 27 species of insects representing 6 orders and 20 families were examined by DEAE cellulose column chromatography to determine the choline/ethanolamine phosphoglyceride ratios, and by gas chromatography to determine the constituent fatty acids.The phosphorus in the ethanolamine phosphoglycerides accounted for approximately 50% of the total lipid phosphorus in aphids (Homoptera) and in all but one family of Diptera (flies) examined while the phosphorus in the choline phosphoglycerides accounted for only about 25%. Ethanolamine and choline phosphoglycerides were present in approximately equal proportions in one family of Diptera and in the Coleoptera (beetles) examined. In the other insects examined choline phosphoglycerides predominated, ethanolamine phosphoglycerides comprising only about 25-30% of total lipid phosphorus as they do in most mammalian tissues.Diptera in which ethanolamine phosphoglycerides were the major phosphatides were also characterized by high proportions of fatty acids less than 18 carbons long, particularly palmitoleic acid, in the neutral lipids. Aphids are characterized by a preponderance of 14-carbon fatty acids. The evidence suggests that predominance of ethanolamine phosphoglycerides is associated with a preponderance of shorter chain fatty acids in the neutral lipids.Differences also exist between Diptera and other insects in the fatty acid compositions of different phosphatides, particularly with respect to the distribution of 18-carbon acids. The compositions observed in insects that contained large amounts of the choline phosphoglycerides are similar to those found in vertebrates. Similarities in fatty acid composition of the choline phosphoglycerides in such widely divergent organisms suggest that the fatty acids may play a greater role in phospholipid function than has heretofore been demonstrated.
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Insect Pathology Research Institute, Saut Ste. Marie, Ontario, Canada.