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

Pistachio and almond mummies have been reported to attract adult navel orangeworm moths in field trapping studies. The volatile profiles of these matrices were recently described. Concurrently, recent investigations have demonstrated that the water activity of almond hulls plays an important role in the production of semiochemicals known to attract the navel orangeworm in almond orchards. In the present study, the water activity of pistachio and almond mummies was increased and the resultant headspace volatiles monitored over the course of a week. The volatile profile of wet pistachio mummies contained 86 volatiles, of which 22 were unique to the wet matrix. The volatile profile of the wet pistachio matrix increased in chemical diversity to include small chain alcohols, benzenoids, and fatty acid breakdown products relative to the dry matrix, which primarily emitted terpenoids. The wet almond mummies emitted a total of 57 volatiles, 37 more than dry almond mummies. Among the volatiles detected in the wet almond mummies were three of the five compounds that are found in the synthetic blend of host plant volatiles known to attract navel orangeworm moths. The volatile bouquets from the wet and dry pistachio mummies, and wet almond mummies were evaluated by electroantennographic (EAG) analysis. Published by Elsevier Ireland Ltd on behalf of Phytochemical Society of Europe.