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  • 1
    ISSN: 1573-1561
    Keywords: Chirality ; enantiomers ; 5-hyroxy-4-methyl-3-heptanone, stereoisomer ; Sitophilus oryzae ; Sitophilus zeamais ; rice weevil ; maize weevil ; aggregation pheromone ; Coleoptera ; Curculionidae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract The chirality of the pheromone of the rice weevil,Sitophilus oryzae (L.), and the maize weevil,S. zeamais (Motschulsky), 5-hydroxy-4-methyl-3-heptanone, was determined using an acetyl lactate derivatization procedure. Maize weevils were shown to produce 〉98% 4S,5R. Determination was more difficult with rice weevils due to a smaller quantity of insect extract, but they were shown to produce at least 92% 4S, 5R. The attractancy of the four synthetic stereoisomers of 5-hydroxy-4-methyl-3-heptanone was tested using rice and maize weevils. As expected, both species were most strongly attracted to the 4S, 5R enantiomer. Maize weevils also showed low but significant responses (P 〈 0.05) to both 4R, 5R and 4S,5S. Rice weevils showed a highly significant (P 〈 0.01) response to 4R, 5S, although it was only about one third the response to 4S, 5R. Thus, (4S,5R)-5-hydroxy-4-methyl-3-heptanone is clearly the major component of the pheromone of bothS. zeamais andS. oryzae.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1573-1561
    Keywords: Chirality ; dimethylhydrocarbons ; stereoselective synthesis ; electrophysiological recording ; (3S, 13R)-3, 13-dimethylheptadecane ; (3R, 13R)-dimethylheptadecane ; (3R, 13S)-dimetylheptadecane ; (3S, 13S)-dimethylheptadecane
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract (3S, 13R)-3, 13-Dimethylheptadecane [(3S, 13R)-3, 13-dime-17Hy] is the major pheromone component of the western false hemlock looper (WFHL),Nepytia freemani. In comparative gas chromotographic-electroantennographic detection (GC-EAD) analyses of stereoselectively synthesized isomers, 1 pg of (3S, 13R)-dime-17Hy elicited significantly stronger electrophysiological responses by male WFHL antennae than did 1 pg of separately injected (3R, 13R)-, (3R, 13S)- or (3S, 13S)-3, 13-dime-17Hy. In field experiments with individually tested stereoisomers. (3S, 13R)-3, 13-dime-17Hy was the only stereoisomer to attract males, but the four-stereoisomer blend was 3.6 times more attractive. Quaternary and all binary combinations of (3S, 13R)-3, 13-dime-17Hy with the other stereoisomers were equally attractive, suggesting that synergisytic behavioral activity in WFHL resided with either one of (3R, 13R)-, (3R, 13S)-, or (3S, 13S)-3, 13-dime-17Hy. Because optical isomers of (di)methylhydrocarbons do not separate on currently available columns, it remains unknown whether female WFHL also produce a four-stereoisomer pheromone blend. Substitutionality of pheromone stereoisomers without loss of behavioural activity has not previously been reported, but favorably compares with the concept of pheromone redundancy that was first suggested for the multiple pheromone component blend of the cabbage looper moth,Trichoplusia ni.
    Type of Medium: Electronic Resource
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