Submitted to: Archives of Insect Biochemistry and Physiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: March 1, 2003
Publication Date: May 16, 2003
Citation: BUCKNER,J.S., HAGEN,M.M., TRIACYLGLYCEROL AND PHOSPHOLIPID FATTY ACID COMPOSITIONS OF THE SILVERLEAF WHITEFLY, BEMISIA ARGENTIFOLII, ARCHIVES OF INSECT BIOCHEMISTRY AND PHYSIOLOGY, 53(2):66-79, 2003. Interpretive Summary: The silverleaf whitefly, Bemisia argentifolii, is a very serious pest of agricultural crops in the southern U.S., including cotton, and a wide range of ornamentals, melons and vegetables. Whitefly nymphs and adults damage crops by extracting large quantities of phloem sap that causes wilting and decreased plant development. Feeding whiteflies also excrete ¿sticky¿ honeydew that contaminates the surroundings and serves as a medium for sooty mold, and they serve as vectors to transmit yield-limiting viruses and other plant disorders. Studies have been conducted on the effective implementation of beneficial insect predators and parasitoids for biological control of whiteflies. The survival and proliferation of these natural enemies of whiteflies is dependent upon the quality and quantity of the nutritional potential of whitefly eggs and nymphs and one of the essential nutritional needs for predacious insects is lipid. The assessment of the internal lipids as a source of nutrient reward is especially relevant to specific parasitoids of whiteflies since they consume their host from within. In this paper we report on the identification and composition of the fatty acids associated with the major lipid classes (triacylglycerols, free fatty acids and phospholipids) within B. argentifolii nymphs and adults. Fourth instar nymphs had 5-10 times the quantities of fatty acids as compared to third instar nymphs and 1-3 times the quantities from adults. For nymphs and adults, triacylglycerols were the major source of saturated and monounsaturated fatty acids, and the major sources of the polyunsaturated fatty acids were the phospholipid fractions.
Technical Abstract: The identification and composition of the fatty acids associated with the major lipid classes (triacylglycerols, free fatty acids, phospholipids) within Bemisia argentifolii Bellows and Perring (Homoptera: Aleyrodidae) nymphs were determined. Comparisons were made to the fatty acids from the internal lipids of B. argentifolii adults. The fatty acids of each lipid class were analyzed as fatty acid methyl esters by capillary gas chromatography. All lipid classes contained variable distributions of eight fatty acids: the saturated fatty acids, myristic acid (14:0), palmitic acid (16:0), stearic acid (18:0), arachidic acid (20:0); the monounsaturated fatty acids, palmitoleic acid (16:1), oleic acid (18:1); the polyunsaturated fatty acids, linoleic acid (18:2), linolenic acid (18:3). Fourth instar nymphs had 5-10 times the quantities of fatty acids as compared to third instar nymphs and 1-3 times the quantities from adults. The quantity differences of fatty acids between fourth and third instar nymphs were related to their size and weight differences. The fatty acid distributions, as percentage composition, for each lipid class were the same for the pooled groups of 3rd and 4th instar nymphs. For nymphs and adults, triacylglycerols were the major source of fatty acids, with 18:1 and 16:0 acids as major components. For nymphs and adults, the majority of the polyunsaturated fatty acids, 18:2 and 18:3 were present in the two phospholipid fractions, phosphatidylethanolamine and phosphatidylcholine.