|Poprawski, Tadeusz - USDA-ARS, WESLACO, TX|
Submitted to: National Research and Action Plan for Silver Leaf Whitefly
Publication Type: Abstract Only
Publication Acceptance Date: December 21, 1999
Publication Date: N/A
Technical Abstract: The cuticular lipid composition of Bemisia argentifolii Bellows and Perring (Homoptera: Aleyrodidae) nymphs parasitized by Eretmocerus mundus Mercet was determined by capillary gas chromatography (CGC) and CGC-mass spectrometry (CGC-MS) and the results compared with the cuticular lipids of unparasitized nymphs and those of nymphs parasitized by Encarsia pergandiella Howard. Previous studies with B. argentifolii nymphs had shown that wax esters were the major components of the cuticular lipids with lesser amounts of hydrocarbons, long-chain aldehydes and long-chain alcohols. As compared to unparasitized controls, no appreciable changes in lipid composition were observed for the cuticular lipids of E. pergandiella-parasitized nymphs. However, the cuticular lipids from nymphs parasitized by E. mundus contained measurable quantities of two additional components in their hydrocarbon fraction. CGC-MS analyses and comparisons with an authentic standard indicated that the two hydrocarbons were the monomethyl-branched alkanes, 2-methyltriacontane (31 carbons) and 2-methyldotriacontane (33 carbons). The occurrences, mechanisms for biosynthesis and possible functions of 2-methylalkanes as cuticular lipid components of insects have been reviewed. Current studies are focusing on determining the site of synthesis of these methyl-branched alkanes and their possible function as chemical cues for host recognition, acceptance and discrimination by E. mundus and other whitefly parasitoids.