Submitted to: Journal of Agricultural and Food Chemistry
Publication Type: Peer reviewed journal
Publication Acceptance Date: 2/10/2004
Publication Date: 5/11/2005
Citation: Light, D.M., Knight, A.L. 2005. Specificity of codling moth (lepidoptera: tortricidae) for the kairomone, ethyl (2e, 4z)-2,4-decadienoate: field bioassays with pome fruit volatiles, analog and isomeric compounds. Journal of Agricultural and Food Chemistry. 53(10):4046-4053. Interpretive Summary: Codling moth, Cydia pomonella (L.) is a severe and the number one pest of apples, pears, and walnuts worldwide, and new approaches for precise monitoring and control management are needed. Control of damaging codling moth populations currently depends on the use of large amounts of broad-spectrum organophosphate insecticides, which are neural poisons for most animals, thus posing severe challenges to the environment and food safety. Alternative control tactics that use selective insecticides and 'selective exposure' tactics that target only the pest are dearly needed. We report the discovery of a highly specific attractant for codling moths, which has unique properties that fulfill the role of allowing 'selective exposure' of just codling moths. We discovered that a common food odor found in pears, called the 'pear ester,' is highly attractive to only codling moths and attracts both males and female moths. The unique attraction of females means we now have a lure ' tool to monitor pest populations and know when control sprayings are truly necessary, time the sprays to be most effective and judiciously use fewer insecticide sprayings. Thus, this pear ester attractant for codling moths should provide future impacts on pest management and help preserve the environment and assure food safety.
Technical Abstract: Codling moth, Cydia pomonella (L.) is a severe pest of apples, pears and walnuts worldwide and new approaches for precise monitoring and management are needed. Twenty-three blends of pome fruit volatiles were tested, of which a single blend of 10-carbon esters showed the only attraction of moths in field bioassays conducted in both walnut and apple orchards. A single constituent of this blend, ethyl (2E, 4Z)-2,4-decadienoate - the 'pear-ester,' was the major contributing attractant, attracting both males and female moths in combined numbers that were comparable to the attractiveness of sex pheromone. Structure ' activity tests were conducted in a series of orchard trials to determine specificity of attraction of codling moths to this kairomone. No analog 10-carbon alcohols, aldehydes, acetates, nor esters elicited moth capture responses. Various analog esters of the (2E, 4Z)-2,4-decadienoic acid elicited differential capture responses, with the ethyl exceeding the propyl, methyl, butyl, and hexyl analogs. The (E, Z)- geometric isomers of this series of (2E, 4Z)-2,4-decadienoic acid esters far exceeded the attractiveness of the (E, E)-isomers. The pear-ester was also non-attractive to other insect species both beneficial and pests of other horticultural fruit crops. The pear-ester is a potent attractant of both sexes and the moth is highly discriminating in structure ' activity attraction to this kairomone. These specificity attributes should allow this kairomone to contribute to new abilities for female monitoring and selective control practices that should decrease the current dependence on use of broad-spectrum insecticides.