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ARS Home » Pacific West Area » Albany, California » Western Regional Research Center » Foodborne Toxin Detection and Prevention Research » Research » Publications at this Location » Publication #246855
Title: Characterization of microencapsulated pear ester, (2E,4Z)-ethyl-2,4-decadienoate: a kairomonal spray-adjuvant against neonate codling moth larvae

Author
item Light, Douglas
item Beck, John

Submitted to: Journal of Agricultural and Food Chemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/17/2010
Publication Date: 6/8/2010
Citation: Light, D.M., Beck, J.J. 2010. Characterization of microencapsulated pear ester, (2E,4Z)-ethyl-2,4-decadienoate: a kairomonal spray-adjuvant against neonate codling moth larvae. Journal of Agricultural and Food Chemistry. 58(13):7838-7845.

Interpretive Summary: Codling moth (CM), Cydia pomonella, is the key pest of apples, pears and walnuts worldwide, causing internal damage by larvae and harmful microorganisms. Neonate CM larvae are highly responsive to a pear-derived kairomone, ethyl (2E,4Z)-2,4-decadienoate, the “pear ester” (PE), evoking attraction and arrestment. Microencapsulated formulation (PE-MEC) enhances the control efficacy of various insecticides used as a spray adjuvant. Reported here is the characterization of the PE-MEC formulation, including microcapsule size, concentrations, and emission rate dynamics. Diameter of the thin-walled microcapsules ranged from 2-14 microgram, with 68.6% of capsules being 2–3 microgram. At the field application dilution of PE-MEC formulation the concentration of microcapsules averaged 265,000 capsules per milliliter spray solution. Headspace collections showed the evaporative emission of PE was similar by PE-MEC concentration. Application of PE-MEC with insecticides may increase neonate foliar wandering, thereby disrupting host location and enhancing mortality by prolonging exposure to insecticide.

Technical Abstract: The codling moth (CM), Cydia pomonella, is the key pest of apples, pears and walnuts worldwide, causing internal feeding damage by larvae and introduction of molds and spoilage micro-organisms. Hatched CM larvae are highly responsive to a pear-derived kairomone, ethyl (2E,4Z)-2,4-decadienoate, the “pear ester” (PE), evoking attraction and arrestment of neonates. A microencapsulated formulation of PE (PE-MEC) when applied, in laboratory pedestrian bioassays, as a dilute spray elicits strong orientation preferences, extended crawling time, frequent turning, and arrestment by CM neonate larvae, thereby promoting “larval wandering” and greater temporal – spatial exposure of neonates on leaves. PE-MEC has been shown in field studies to enhance the control efficacy of various insecticides when tank-mixed as a spray-adjuvant. Reported here is characterization of the PE-MEC formulation, including microcapsule size, concentrations, and emission rate dynamics. Diameter size of the thin-walled microcapsules ranged from 2 to 14 microns, with 68.6% being 2–3 microns. At the field application dilution of PE-MEC formulation in spray water (1:3200), the concentration of microcapsules averaged 264,600 capsules per milliliter spray solution. SPME headspace collections and GC-MS analysis showed the evaporative emission of PE over 21 days varied by concentration of microcapsules applied to filter paper substrates and followed power trendline decay curves. Extrapolations of the trendlines suggest picogram emissions of PE would extend to 2.5 – 3 weeks. Applications of PE-MEC spray adjuvant with insecticides may evoke an increase in neonate wandering upon foliage, thereby disrupting host fruit/nut finding, as well as enhancing mortality by increasing the exposure to insecticides.