Electrophysiological responses of male and female Amyelois transitella antennae to pistachio and almond host plant volatiles

Authors: Beck, John; Light, Douglas; Gee, Wai

Submitted to: Entomologia Experimentalis et Applicata
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/8/2014
Publication Date: 11/4/2014
Publication URL: http://handle.nal.usda.gov/10113/59893
Citation: Beck, J.J., Light, D.M., Gee, W.S. 2014. Electrophysiological responses of male and female Amyelois transitella antennae to pistachio and almond host plant volatiles. Entomologia Experimentalis et Applicata. 153(3):217-230. doi: 10.111/EEA.12243.

Interpretive Summary: The navel orangeworm, Amyelois transitella, is a major insect pest of California almonds, pistachios, and walnuts. The larvae of A. transitella feed on kernels inflicting damage and lowering nut kernel quality. Moreover, larvae carry spores of fungi which produce toxic metabolites, thus resulting in international food safety concerns. A. transitella moths have proven difficult to monitor and control for over four decades, with recently reported progress toward attractants using pheromone and host plant volatile blends. Despite the recent advances of a host plant odor attractant blend that is effective for monitoring moth populations in almond orchards, the blend’s attractancy and capture efficacy of A. transitella has not translated to pistachio orchards. The apparent orchard specificity of A. transitella to the blend suggests a different composition of host plant odors is needed to either improve the current blend or a new blend formulation is required for monitoring in pistachio orchards. The objective of this study was to evaluate available individual odors via a standardized electroantennographic analysis puff method. A total of 106 odors, demarcated into 12 classes of compounds, and from various reports of headspace analysis of pistachio and almond tissues were evaluated individually for their ability to elicit an electrophysiological response from excised male and female A. transitella antennae. Considered broadly across compound class, the male antennae responded on average (numerically) higher to alcohols, aldehydes, alkyls, aromatics, esters, ketones, lactones, and spiroketals. Female antennae responded on average (numerically) higher to benzenoids, mono- and sesquiterpenes, and short-chain alcohols.

Technical Abstract: The polyphagous navel orangeworm, Amyelois transitella (Lepidoptera: Pyralidae), is a major insect pest of California tree nuts. The larvae of A. transitella feed on kernels inflicting damage and lowering nut kernel quality. Moreover, larvae vector aflatoxigenic aspergilli resulting in international food safety concerns. A. transitella moths have proven difficult to monitor and control for over four decades, with recently reported progress toward attractants using pheromone and semiochemical blends. Despite the recent advances of a host plant volatile attractant blend that is effective for monitoring moth populations in almond orchards, the blend’s attractancy and capture efficacy of A. transitella has not translated to pistachio orchards. The apparent orchard specificity of A. transitella to the blend suggests a different composition of host plant volatiles is needed to either improve the current blend or a new blend formulation is required for monitoring in pistachio orchards. The objective of this study was to evaluate available individual volatiles via a standardized electroantennographic analysis puff method. A total of 106 volatiles, demarcated into 12 classes of compounds, and from various reports of headspace analysis of pistachio and almond tissues were evaluated individually for their ability to elicit an electrophysiological response from excised male and female A. transitella antennae. Considered broadly across compound class, the male antennae responded on average (numerically) higher to alcohols, aldehydes, alkyls, aromatics, esters, ketones, lactones, and spiroketals. Female antennae responded on average (numerically) higher to benzenoids, mono- and sesquiterpenes, and short-chain alcohols. The three highest responses elicited from the male antennae were for 2-heptanol, sabinene hydrate, and 3-octen-2-one (877 'V ± 44; 799 'V ± 49; 794 'V ± 42, respectively). The three highest responses elicited from the female antennae were for sabinene hydrate, (Z)-ocimene, and (1S)-a-pinene (942 'V ± 57; 802 'V ± 98; 648 'V ± 58, respectively). The top 25 volatiles for male and female antennal response had averages of 599 'V ± 28 (range 428-877 'V) and 518 'V ± 27 (range 366-942 'V), respectively.