Comparison of the volatile emission profiles of ground almond and pistachio mummies: part 2 - critical changes in emission profiles as a result of increasing the water activity

Authors: Beck, John; Mahoney, Noreen; Cook, Daniel; HIGBEE, BRADLEY - Paramount Farming Company, Inc; Light, Douglas; Gee, Wai; Baig, Nausheena

Submitted to: Phytochemistry Letters
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/7/2014
Publication Date: 1/23/2014
Publication URL: http://handle.nal.usda.gov/10113/58790
Citation: Beck, J.J., Mahoney, N.E., Cook, D., Higbee, B.S., Light, D.M., Gee, W.S., Baig, N. 2014. Comparison of the volatile emission profiles of ground almond and pistachio mummies: part 2 - critical changes in emission profiles as a result of increasing the water activity. Phytochemistry Letters. 8:220-225. DOI: org/10.1016/j.phytol.2014.01.004.

Interpretive Summary: The navel orangeworm moth is a major insect pest to almond and pistachio orchards of California. Field trapping studies are performed to help researchers find new ways to attract and help control this insect pest. Recent field trapping studies of pistachio and almond mummies have been reported to attract adult navel orangeworm moths. Mummies are almond or pistachios that remained on the tree or ground from previous harvests. Recent work in these laboratories has demonstrated that the addition of water to almond hulls plays an important role in the production of key odors that are known to attract the navel orangeworm in almond orchards. In this present study, the odors of the wet pistachio mummies and wet almond mummies were monitored over the course of a week. Four of the five components of a synthetic blend of host plant volatiles known to attract navel orangeworm moths were detected in the wet almond mummies. This result further demonstrates the role that water can play with respect to the odors emitted. The odors of wet pistachio mummies changed from primarily consisting of a class of compounds called terpenoids to an increase in other chemical classes of odors. This change in chemical composition of the odors may play an important role in attracting the navel orangeworm.

Technical Abstract: In recent field trapping studies ground pistachio and almond mummies were reported to attract adult navel orangeworm moths, which showed a slight preference for the dry pistachio mummy matrix depending on the year evaluated. Recent work in these laboratories has demonstrated that the water activity of almond hulls plays an important role in the production of key volatiles that are known to attract the navel orangeworm in almond orchards. In this present study, the volatile headspace of the wet pistachio mummies and wet almond mummies were monitored over the course of a week. Remarkably, four of the five components of a synthetic blend of host plant volatiles known to attract navel orangeworm moths were detected in the headspace of the wet almond mummies further corroborating the importance of water activity for volatile emission profiles. The volatile profile of wet pistachio mummies changed from primarily consisting of terpenoids to in increase in the chemical diversity of the sample and included small chain alcohols, benzenoids, and fatty acid breakdown products. Additionally, the volatile bouquets from the wet and dry pistachio mummies, and wet almond mummies were evaluated by electroantennographic (EAG) analysis. The antennal responses to the volatile bouquets were dry pistachio > wet almond > wet pistachio. Reported also are preliminary field trapping data of the matrices.