7.11- Hexadecadienyl acetate

A mixture of (2, 2 )-ll,13-hexadecadienyl acetate and (Z,E)-11,13,15-hexadecatrienyl acetate was identified as the female (synergistic) sex pheromone of the oak processionary moth, Thaumetopoea processionea (Lepidoptera Thaumetopoeidae). In field experiments, a combination of both esters attracted a significant number of male moths, but not when used individually in traps. 

Female variability in ratio production has not been determined for G. molesta, but it is established for P. gossypiella (Collins and Carde, 1985). The mean ratio of the (Z,Z)- and (Z, )-isomers of the 7,11-hexadecadienyl acetate components is 56 44, with little variability (coefficient of variation, 5.3%). Based on field tests with a range of lures, the response of males broadly overlaps the ratios produced by females (Haynes and Baker, 1988) and also the males threshold for response is equivalent for the range of ratios produced by females (Linn and Roelofs, 1985). One consequence of this in P. gossypiella is that a male would not select a female based on the range of ratios that the females emit. 

H. nuttalli, optimal attraction of H. eglanterina occurs with a blend of three components ( , Z)-10,12-hexadecadienal, ( , Z)-10,12-hexadecadienol, and (E,Z)- 0, 2-hexadecadienyl acetate. In the Robinson Summit population near Ely, Nevada, where both species co-occur, males of H. eglanterina are attracted to a two-component blend of the alcohol and aldehyde, and addition of the (E,Z) 10,12-hexadecadienyl acetate does not augment attraction. 

Insects make unsaturated as well as saturated hydrocarbons. The former as well as long-chain alcohols and their esters often form the volatile pheromones with which insects communicate. Thus, the female pink bollworm attracts a male with a sex pheromone consisting of a mixture of the cis,cis and cis,trans isomers of 7,11-hexadecadienyl acetate,13 and European corn borer males are attracted across the cornfields of Iowa by czs-ll-tetradecenyl acetate.14 Addition of a little of the trans isomer makes the latter sex attractant much more powerful. Since more than one species uses the same attractant, it is possible that the males can distinguish between different ratios of isomers or of mixtures of closely related substances. 

The gelechid moth Pectinophora gossypiella uses (7Z,llZ)-7,ll-hexadecadienyl acetate 300 and (7Z, 11 )-7,11-hexadecadienyl acetate 313 as its sex pheromones. Another moth of the same family, the angouis grain moth Sitotroga cerealella uses only the (Z, )-compound 313. Sonnet synthesized the (Z,Z)-7,11-alkadienyl acetate... 

Reduction in catches of P. gossypiella lasted for about two weeks when the formulation of the pheromone (a 1 1 mixture of (Z,E)- and (Z,Z)-7,ll-hexadecadienyl acetate) was applied at a level of 5 gm a.i. per ha (Fig. 6). When the formulation was applied at 20 gm a.i. per ha, 97% or greater reduction in trap catches was maintained for at least four weeks even when moth catches in the untreated plots were very high (Fig. 7). Similar results were obtained with a hollow fibre formulation (4) of the pheromone applied at similar rates by hand (Figs. 8 and 9). 

We have realized total synthesis of 7Z,llZ-hexadecadienyl acetate and 7Z,11E-hexadecadienyl acetate - sex pheromone of pink bollworm moth (Pectinophora gossypiella) via cometathesis of COD with 1-hexene (Scheme 4). 

As far as we know, there are only four publications devoted to cometathesis of COD with 1-hexene for pheromone synthesis of pink bollworm moth Pectinophora gossypiella) [31-34]. In 1973 Hammel et al recognized that a sex pheromone of this pest is a blend of 7Z,1 IZ-hexadecadienyl acetate and its corresponding Z,E-isomer [35]. It was shown later that the isomer ratio produced by the insect females depends on the geographic area of habitants. As a rule the natural content of Z,Z-isomer is about 56-62% [36-38]. Haynes et al found that the effectiveness of the action of artificial sex... 

Intact sensing structures (chemoreceptors) from natural sources provide an alternative to binding proteins for a range of small molecules. Crab antennules from the blue crab Calinectes sapidus are sensitive to amino acids and display some selectivity, e.g., the antennules contain a receptor for glutamate which is unresponsive to other amino acids such as glycine, alanine, proline, and taurine (26). Olfactory structures in other species offer selectivity for additional types of molecule which act as pheromones, e.g. the male moth Bombyx mori has specific receptors for the female sex attractant bombykol, and Antherea polyphemus has receptors for E6, Zll-hexadecadienyl acetate and E6, Zll-hexadecadienal. 

The most attractive ratio of (Z,Z)- and (Z, )-7,ll-hexadecadienyl acetate (529 a and 529 b Scheme 91) for the pink boll worm, Pectinophora gossypiella, was claimed to be 1 1 (79, 233). Rothschild 286) found that three species, P. gossypiella, P. endema and P. scutigem, were maximally attracted to ratios of 1 1, 1 0.5 and 1 0.1 Z,Z, to Z,E and indicated that these ratios may provide a mechanism for reproductive isolation. Flint et al. 287) have recently shown that the most attractive ZZ to ZE ratio for the pink boll worm varies with the time of year. In the early season a 2 1 ratio was considerably more attractive than a 1 1 ratio, and, as the season progressed, the response maximum was obtained with a much wider range of ratios. Various ratios of ZZ to ZE isomers have been claimed to be most effective 287). 

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