Monoenyl hydrocarbons in female body wax of the yellow peach moth as synergists of aldehyde pheromone components

Abstract

The non-polar components of female body wax and pheromone gland extracts of the yellow peach moth synergistically enhanced male behavioral responses from close to pheromone sources in wind tunnel tests when mixed with an aldehyde pheromone blend. When the nonpolar fractions (NPFs) of female body wax were further separated by column chromatography, synergistic activities were found in the 3 and 50% ether in hexane fractions, and they additively increased male responses. The main components of the first fraction were (Z)-9-tricosene, (Z)-9-pentacosene, (Z)-9-heptacosene, (Z)-9-nonacosene and (Z)-9-hentriacontene. Only (Z)-9-heptacosene showed a significant synergistic effect in enhancing male responses, but the other components had no effect. A mixture of the five monoenyl hydrocarbons lost activity at lower doses than 5 ng. Natural ratios of these hydrocarbons in the female body wax and pheromone gland extracts were similar, but the amount of (Z)-9-heptacosene in the female body wax was significantly higher than in the pheromone gland extracts. We conclude that (Z)-9-heptacosene increases male responses to aldehyde pheromones, and unknown component(s) in the 50% ether in the hexane fraction are required for full synergistic enhancement by the NPFs of the female body wax and the pheromone gland extracts.

Unsaturated Cuticular Hydrocarbons Synergize Responses to Sex Attractant Pheromone in the Yellow Peach Moth, Conogethes punctiferalis

“…Although Z3, Z6, Z9-23:HC alone or the mixture of all four trienes enhanced responses to the aldehyde blend, the responses were not as high as those elicited by the non-polar fraction of female body wax extracts or crude pheromone extracts. Similar reduced responses, compared to whole extracts, had also been observed by addition of Z9-27:HC and a mixture of other monoenes (Xiao et al, 2011). Thus, we tested the effects of mixtures of the monoenes and trienes added to the aldehyde blend.…”

“…In yellow peach moth, the factors underlying the quantitative dimorphism of trienes between males and females have not been investigated. We had previously reported that body wax extracts of female and male yellow peach moth contained the same monoene hydrocarbons (Xiao et al, 2011). Our results indicate that there is little sex specificity for most of the unsaturated hydrocarbons in body wax, but that one or more key components may be increased in females to provide a sex-specific signal.…”

“…In order to improve the relatively poor performance of the pheromone lure for the yellow peach moth, we searched for new pheromone components, and showed, in wind tunnel tests, that two fractions of crude pheromone gland extract or female body wax extract enhanced short-range male responses to the standard lure of E10-16:Ald and Z10-16: Ald. We initially identified Z9-27:HC as a synergist of the aldehyde blend (Xiao et al, 2011), but bioassays demonstrated that there must be additional compounds. In the work described here, we identified a second synergist, Z3, Z6, 9Z-23:HC.…”

“…The components in the 3 % ether fraction were identified as a series of homologous monounsaturated hydrocarbons, among which (Z)-9-heptacosene (Z9-27:HC) enhanced male responses at short distances from the aldehyde source. However, blends of Z9-27:HC, or the entire monoene fraction, added to the aldehydes were still not as active as blends of the aldehydes with crude extracts of female body wax (Xiao et al, 2011), suggesting that there were additional active components in the 50 % ether/hexane fraction.…”

“…Chemicals E10-16:Ald and Z10-16:Ald were obtained from Shin-Etsu Chemical Co. Ltd. (Tokyo, Japan), and a mixture of these two aldehydes (ratio of 95.5:4.5) was prepared after purification (each 99.5 % pure) by chromatography over 10 % AgNO3-impregnated silica gel. (Z)-9-Tricosene (Z9-23:HC), (Z)-9-nonacosene (Z9-29:HC), (Z)-9-pentacosene (Z9-25:HC), Z9-27:HC, and (Z)-9-hentricontene (Z9-31: HC) were synthesized by Z-selective Wittig reactions of the corresponding aldehydes with the C9-ylide generated by mixing KHMDS and n-nonyltriphenylphosphonium bromide, as described in Xiao et al (2011). Four trienyl hydrocarbons were synthesized by reduction of the linolenic ester to the corresponding alcohol, followed by tosylation and chain extension with the appropriate dialkyllithium cuprates or alkylmagnesium bromides (Conner et al, 1980;Underhill et al, 1983).…”