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United States Department of Agriculture

Agricultural Research Service

Title: Field and Laboratory Studies to Improve Pheromone of Navel Orangeworm

Authors
item Millar, Jocelyn - UC RIVERSIDE
item KUENEN, LODEWYK

Submitted to: California Pistachio Commission Production Research Report
Publication Type: Trade Journal
Publication Acceptance Date: December 1, 2003
Publication Date: March 1, 2004
Citation: Millar, J.G., Kuenen, L.P. 2004. Field and laboratory studies to improve pheromone of navel orangeworm. California Pistachio Commission Production Research Reports. 136-160.

Interpretive Summary: Extensive field trials with numerous batches and formulations of putative primary sex pheromone component, alone and in combination with minor components identified from pheromone glands of female Navel Orangeworm (NOW), all resulted in relatively low trap catches of male NOW in comparison to traps baited with live female NOW. In an attempt to resolve this impasse, we began a careful examination of the pheromone chemistry of the related species Pyralis farinalis. First, we verified that unmated P. farinalis females were indeed attractive to male NOW in field trials. We then extracted P. farinalis pheromone glands, and analyzed the extracts by coupled gas chromatography-electroantennogram detection [GC/EAD: this method separates the components of a chemical blend (GC) and then these compounds are sequentially exposed to the antenna (olfactory organ in insects) of male moth (EAD). Any strong electrical signals generated by the moth antenna are usually indicative of a component in the sex pheromone of that species]. These analyses revealed a new component that produced responses from both P. farinalis antennae and from NOW antennae. Comparison of pheromone gland extracts from both species determined that this compound is present in both species. This compound was missed in previous analyses because it is present in trace amounts, it stimulates only weak responses from NOW antennae, and its chemical and physical properties are quite different than those of typical moth pheromone components. Assays are in progress to verify that this compound enhances the attraction of male NOW.

Technical Abstract: Extensive field trials with numerous batches and formulations of Z11,Z13-16:Ald, alone and in combination with minor components identified from pheromone glands of female Navel Orangeworm (NOW), all resulted in relatively low trap catches of male NOW in comparison to traps baited with live female NOW. It appeared that the Z11,Z13-16:OH might increase trap catch slightly, but not to the level of the female-baited traps. In an attempt to resolve this impasse, we began a careful examination of the pheromone chemistry of the related species Pyralis farinalis, which is reported to cross-attract NOW males. First, we verified that unmated P. farinalis females were indeed attractive to male NOW in field trials. We then extracted P. farinalis pheromone glands, and analyzed the extracts by coupled gas chromatography-electroantennogram detection, using live antennae from males of both P. farinalis and NOW. These analyses revealed a new component that produced strong responses from P. farinalis antennae, and weaker responses from NOW antennae. Comparison of pheromone gland extracts from both species determined that this compound is present in both species, and it may be a critical minor component in the complete pheromone blends of both species. This compound was missed in previous analyses because it is present in trace amounts, it stimulates only weak responses from NOW antennae, and its chemical and physical properties are quite different than those of the other pheromone components. Assays are in progress to verify that this compound enhances the attraction of male NOW to Z11,Z13-16:Ald.

Last Modified: 9/10/2014
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