| Abstract
| - Codling moth, Cydia pomonella (L.), is a severe pest of apples, pears, and walnuts worldwide, andnew approaches for precise monitoring and management would be beneficial. Ninety-two pome fruitvolatiles were formulated in 23 distinct blends, of which a single 4-component blend of 10-carbonesters showed the only significant attraction of moths in field bioassays conducted in both walnutand apple orchards. A single constituent of this blend, ethyl (2E,4Z)-2,4-decadienoatethe “pearester”, was the major contributing attractant. The pear ester attracted both male and female mothsin combined numbers that were comparable to the attractiveness of conspecific sex pheromone.Structure−activity tests were conducted in a series of orchard trials to determine the specificity ofattraction of codling moths to the pear ester kairomone. No analogue 10-carbon alcohols, aldehydes,acetates, or other esters elicited significant moth capture responses. Tests with various analogueesters with alcohol chain length moiety substitutions of the (2E,4Z)-2,4-decadienoic acid eliciteddifferential capture responses, with the ethyl exceeding the propyl, methyl, butyl, and hexyl analogues.The (E,Z) geometric isomers of this series of (2E,4Z)-2,4-decadienoic acid esters far exceeded theattractiveness of the (E,E) isomers. The pear ester is a potent attractant of both males and females,and codling moths are highly discriminating and specific in their structure−activity-based attractionto this pear-derived kairomone. These specificity attributes should allow this host plant kairomone tocontribute to new abilities for female monitoring and the potential of development of novel and highlyselective control practices that should decrease the current dependence on the use of broad-spectruminsecticides. Keywords: Kairomone; attractant; pear ester; host plant volatiles; codling moth; Cydia pomonella;monitoring; isomers; structure−activity
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