In Situ Seasonal Study of the Volatile Production of Almonds (Prunus dulcis) Var. ‘Nonpareil’ and Relationship to Navel Orangeworm

Abstract

Nonpareil almonds, Prunus dulcis , account for the largest percentage of almond varieties grown in the Central Valley of California. Several studies have investigated the various nonvolatile 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 a 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 the continued presence of NOW, the identification of particular VOCs and their relationship to NOW have 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, beta-bourbonene, and tetradecane were present for the majority of the days investigated. Several VOCs exhibited positive electroantennographic signals from male and/or female NOW moths.

Volatile emissions from the flea beetle Altica litigata (Coleoptera: Chrysomelidae) associated with invasive Ludwigia hexapetala

“…A second experiment with identical number of flea beetles was performed concurrently. Volatile collections were performed at room temperature via solid-phase microextraction (SPME) 100 lm polydimethylsiloxane fibers (Supleco) with the following parameters (Beck et al 2008(Beck et al , 2009: P, permeation of volatiles within the container = 3 h; E, exposure of SPME fiber to volatiles = 1 h; S, storage time of adsorbed volatiles = 1 min; and T, thermal desorption of volatiles on SPME fiber onto GC column = 10 min. Air exchange for the flea beetles was allowed via an 18 gauge needle placed in the septum overnight.…”

“…Volatiles were collected in situ from L. hexapetala in their natural habitat (Delevan NWR) both with and without A. litigata present using custom Teflon collection bags and SPME fibers (Beck et al 2008(Beck et al , 2009 in early August 2010 ( Fig. 1a-c).…”

“…9 0.25 lm) installed. The GC-MS parameters were identical to previously described programs (Beck et al 2009). A third GC-MS (Agilent 6890N coupled to a 5975B) with an Astec Chiraldex B-DM enantioselective column (Supelco) installed was used for further compound verification and attempts to separate Volatile emissions from the flea beetle Altica litigata 255 stereoisomers of Compound A (Fig.…”

Electroantennographic Bioassay as a Screening Tool for Host Plant Volatiles

“…The 1:2:4 ratio in the second blend incorporates the relative ratios of volatiles detected during the GC-MS analysis. 4 However, the use of SPME and GC-MS provide only relative ratios and the use of GC-FID analysis in conjunction with calibration curves of the classes of compounds is recommended for a more accurate starting point for ratios based on volatiles detected.…”

“…For the initial screening 10 stimulus pipettes (N=4 for each male and female) are loaded in the event of a bad prep or other unforeseen obstacle. 4. Using a pair of tweezers, gently fold the bioassay disc in half to facilitate placement into the pipette, then partially place the folded disc into the large end of the pipette so that ca.…”