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An unusual mechanism for hydrocarbon biosynthesis is proposed from work examining the formation of (Z)-9-tricosene (Z9-23:Hy), the major sex pheromone component of the female housefly, Musca domestica. Incubation of (Z)-15-[1-'4C1-and (Z)-15- [15,16-3H2jtetracosenoic These data demonstrate an unusual mechanism for hydrocarbon formation in insects in which the acyl-CoA is reduced to the corresponding aldehyde and then carbon-1 is removed as CO2. The requirement for NADPH and 02 and the inhibition by CO and the antibody to cytochrome P450 reductase strongly implicate the participation of a cytochrome P450 in this reaction.Long-chain hydrocarbons are abundant components in the cuticular lipids of plants and insects (1, 2), where they function to prevent water loss from the surface of the organism. In some insect species, including the housefly, Musca domestica, hydrocarbon components function as sex pheromones. The main component of the sex pheromone produced by the female housefly is (Z)-9-tricosene (Z9-23:Hy) (3), which functions as a short-range attractant and stimulant (4). In vertebrates, hydrocarbons function in the myelin sheath of peripheral nerves (5) and as components of uropygial gland secretions (6).The mechanism for hydrocarbon biosynthesis has proven to be elusive. Studies in the 1920s (7) suggested that two fatty acids condense head-to-head to form a ketone that is then reduced to the alkane. In an elegant series of experiments in the 1960s (reviewed in ref. -8), Kolattukudy and coworkers demonstrated that hydrocarbons are formed by the elongation of fatty acids, which are then converted to hydrocarbon by the loss of the carboxyl group, which was presumed to be a decarboxylation reaction (9,10). More recently, Kolattukudy and coworkers have obtained evidence from studies in a microorganism (11,12), a plant (13), a vertebrate (6), and an insect (14) that long-chain fatty acyl groups are reduced to aldehydes and then converted to hydrocarbons by a reductive decarbonylation mechanism. This mechanism does not require reduced pyridine nucleotides, and the carbonyl carbon is released as CO. In contrast, Gorgen and coworkers (15,16) presented evidence that 1-alkenes are formed by a decarboxylation mechanism in both plants and insects. We present evidence in this paper that hydrocarbon formation in the housefly occurs by the reduction of a long-chain acyl-CoA to an aldehyde that is then converted to the hydrocarbon and CO2 by a reaction that requires NADPH and 02 and involves cytochrome P450.

New types of sucrose esters have been synthesized and shown to be potent insecticides against sweet potato whiteflies. On the basis of the structures of natural sucrose esters isolated from various Nicotiana species and which were shown to be potent whitefly insecticides, it was decided to synthesize similar sucrose esters. Specific conditions were worked out for the reaction of acid chloride with sucrose to yield a series of mono-, di-, tri-, and tetraacyl sucroses. As the active sucrose esters of Nicotiana species contain mainly heptanoic and octanoic acids esterified to sucrose, C6−C12 aliphatic acid sucrose esters were prepared. Capillary gas chromatography of their TMS derivatives showed that distinct groups of isomers were produced. Separation by silicic acid chromatography produced fractions containing individual groups of monoacyl sucroses, diacyl sucroses, triacyl sucroses, etc. Evaluations of individual groups of the C6−C12 acid sucroses showed that diheptanoyl sucroses, dioctanoyl sucroses, and dinonanoyl sucroses were most active against whiteflies and aphids. Details of syntheses, separations, GC and NMR data, and whitefly assays are presented. Keywords: Sugar esters; insecticides; whiteflies; aphids; chromatography; syntheses; bioassays; correlation

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