Sex pheromones of many Lepidopteran species have relatively simple structures consisting of a hydrocarbon chain with a functional group and usually one to several double bonds. The sex pheromones are usually derived from fatty acids and provide a key to defining their specific biosynthetic pathways. We investigated the incorporation of the precursors, D3-16:Acid and D3-18:Acid, into pheromone components of Helicoverpa zea and Helicoverpa assulta. The major pheromone component for H. zea is Z11-16:Ald while H. assulta utilizes Z9-16:Ald. We found that H. zea uses a 16-carbon fatty acid to form Z11-16:Ald via D11 desaturation and reduction, but also requires an 18-carbon fatty acid to biosynthesize Z9-16:Ald and Z7-16:Ald via the D11 desaturation or D9 desaturation and one round of chain-shortening. H. assulta uses a 16-carbon fatty acid to form Z9-16:Ald, Z11-16:Ald and 16:Ald. The amount of labeling indicated that the D9 desaturase is the major desaturase present in the pheromone gland cells. In the evolution of desaturases, H. assulta may be the more primitive Helicoverpa species, but this requires further study.
Species 1: Lepidoptera Noctuidae Helicoverpa zea (corn earworm)
Species 2: Lepidoptera Noctuidae Helicoverpa assulta (oriental tobacco budworm)
Keywords: Pheromone biosynthesis, PBAN,desaturase
The ESA 2001 Annual Meeting - 2001: An Entomological Odyssey of ESA