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Title: Identification and biosynthesis of the hydrocarbon sex pheromone in Utetheisa ornatrix (Lepidoptera: arctiidae)

item Zhang, Aijun

Submitted to: Journal of Chemical Ecology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/30/2007
Publication Date: 5/18/2007
Citation: Choi, M., Lim, H., Park, K., Adlof, R., Wang, S., Zhang, A., Jurenka, R. 2007. Identification and biosynthesis of the hydrocarbon sex pheromone in Utetheisa ornatrix (Lepidoptera: arctiidae). Journal of Chemical Ecology. 33:1336-1345.

Interpretive Summary: Certain type of common compounds has been used by numerous moths distributed worldwide as the sex attractant for mate location. However, how these moths made those attractants are unclear. We made certain chemically-labeled compounds and introduced into female moths. Our experimental results demonstrated that these female insects directly took some compounds from plant tissue, modified chemical structures, and incorporated into her sex attractants. This finding will help scientists understand the biosynthetic pathway of moth sex attractants and facilitate the pest management program to protect many agricultural important corps from moth damage.

Technical Abstract: Sex pheromones are utilized by many female moths to attract and successfully mate with a conspecific male. The type II class of sex pheromones found in moths are composed of polyene hydrocarbons and their epoxides. Analysis by GC-MS and GC-EAD response of male moths confirmed that 1,3,6,9-21:Hy is a major pheromone component and 3,6,9-21:Hy is a minor component in this Utetheisa ornatrix population. Both components were detected from pheromone glands of newly-emerged adults and low amounts were found in the late pupal stage, indicating that sex pheromone biosynthesis started in the late pupal stage and reached a maximum amount in 1-day-old female adults. In our population of females ~ 90% produced the tetraene, 1,3,6,9-21:Hy, as the major component. About 10% of the female moths in our colony produced only a large amount of 3,6,9-21:Hy, 1500 - 2000 ng, with no evidence of the tetraene. This frequency was very consistent throughout our analysis of several hundred female moths. This result could indicate that two populations are mixed in our collection area of Florida. Decapitated female moths accumulated 3,6,9-21:Hy and 1,3,6,9-21:Hy compared to the same age normal female, indicating that female moths continuously produce pheromone but the pheromone was not released. A PBAN-like neuropeptide did not affect sex pheromone production as indicated by decapitation of U. ornatrix female adults. When the labeled precursor D4-9,12,15-18:acid was injected into the early pupal stage, the most abundantly labeled hydrocarbons were 3,6,9-21:Hy and 1,3,6,9-21:Hy in the female adults. This result indicates that 3,6,9-21:Hy could be biosynthesized from linolenic acid derived from host plant through chain elongation and decarboxylation. To help determine how 1,3,6,9-21:Hy is produced, D4-3,6,9-21:Hy was injected into pupae and monitored for label incorporation. No label was incorporated in 1,3,6,9-21:Hy, although a large amount of triene, 3,6,9-21:Hy, was labeled. This indicates that U. ornatrix females does not use 3,6,9-21:Hy to produce 1,3,6,9-21:Hy and the terminal double bond is introduced earlier in the biosynthetic pathway.