ARS | Publication request: In situ volatiles from a single cultivar of Prunus dulcis and their relationship to navel orangeworm

Submitted to: Entomological Society of America Annual Meeting
Publication Type: Proceedings
Publication Acceptance Date: March 14, 2009
Publication Date: N/A

Interpretive Summary: Nonpareil almonds, Prunus dulcis, account for the largest percentage of almond varieties grown in the Central and San Joaquin valleys of California. Several studies have investigated the various non-volatile and volatile components of various plant parts; however, the volatile organic compound (VOC) emission of almonds from a single cultivar has not been studied over the course of an entire growing season. This aspect is particularly relevant to research concerning the navel orangeworm (NOW), a major insect pest of almonds and other tree nuts. Despite several flights of NOW, the identification of particular VOCs, or their potential correlation to NOW flights, has not been addressed. The VOC emission of Nonpareil almonds was collected utilizing a small collection bag while the almonds were still on-tree (in situ), and over the course of a growing season by solid-phase microextraction (SPME). The adsorbed VOCs were thermally desorbed from the SPME fiber and analyzed directly via gas chromatography, mass spectroscopy (GC-MS). The VOCs (Z)-hex-3-enyl acetate, (Z)-hex-3-enyl butyrate, undecan-2-ol, '-bourbonene, caryophyllene, and '-humulene exhibited distinct emission patterns during the 1st and 2nd flights of NOW. Several VOCs exhibited positive electroantennographic (EAG) signals from male and female NOW moth bioassays, implying molecular recognition of select VOCs by the NOW moths. While these select VOCs produced positive EAG signals, their responses were a small percentage of the male NOW’s response to the pheromone component, (Z,Z)-11,13-hexadecadienal.

Technical Abstract: Nonpareil almonds, Prunus dulcis, account for the largest percentage of almond varieties grown in the Central and San Joaquin valleys of California. Several studies have investigated the various non-volatile and volatile components of various plant parts; however, the volatile organic compound (VOC) emission of almonds from a single cultivar has not been studied over the course of an entire growing season. This aspect is particularly relevant to research concerning the navel orangeworm (NOW), a major insect pest of almonds and other tree nuts. Despite several flights of NOW, the identification of particular VOCs, or their potential correlation to NOW flights, has not been addressed. The VOC emission of Nonpareil almonds was collected in situ over the course of a growing season by solid-phase microextraction (SPME). The VOCs (Z)-hex-3-enyl acetate, (Z)-hex-3-enyl butyrate, undecan-2-ol, '-bourbonene, caryophyllene, and '-humulene exhibited distinct emission during the 1st and 2nd flights of NOW. Several VOCs exhibited positive electroantennographic (EAG) signals from male and female NOW moth bioassays.