Hull Split and Damaged Almond Volatiles Attract Male and Female Navel Orangeworm Moths

Abstract

A blend of volatiles derived from the emissions of almonds at hull split and mechanically damaged almonds was compared to almond meal, the current monitoring standard for the insect pest navel orangeworm (NOW). Field trapping studies were performed to determine the blend's ability to attract adult NOW. The blend comprised racemic 1-octen-3-ol, ethyl benzoate, methyl salicylate, acetophenone, and racemic (E)-conophthorin. Ethyl acetate was used as a solvent with a blend component concentration of 100 mg/mL. The blend attracted both sexes of NOW when tested in five 2-week intervals spanning the first three flights of NOW in commercial almond orchards in the southern Central Valley of California. The blend demonstrated consistently higher capture rates for female NOW throughout the evaluation period, but unlike almond meal it significantly attracted males. Reported is a survey of the major and minor volatiles emitted from almonds at hull split, the key period of vulnerability to NOW infestation. Also reported is the attractancy of a formulated test blend based on the host plant volatile emissions, electroantennographic screening experiments, and field trapping studies. The results of this test blend highlight progress toward a host-plant-based attractant for NOW, a major insect pest of California tree nuts that presently lacks an adequate monitoring tool.

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

“…Moreover, where the female top 25 volatiles had all five components of the bisexually attractive synthetic blend, only two of the volatiles, 1-octen-3-ol and acetophenone, were in the top 25 volatiles for males, with the other co-attractant volatiles ranking at 35 (conophthorin), 45 (ethyl benzoate), and 53 (methyl salicylate). In almond orchards this synthetic five-component blend attracts wild male moths in slightly greater numbers than female moths (Beck et al, 2012a), despite the chemoreceptive sensitivities/affinities to these key volatiles being greater for female navel orangeworm antennae.…”

“…Another noteworthy observation from Figure 2 and the top 25 volatiles eliciting female antennal responses was the inclusion of all five components of a synthetic host plant volatile blend shown for the past 3 years to attract both sexes of navel orangeworm moths in almond orchards (Beck et al, 2012a;Beck & Higbee, 2013). Ethyl benzoate (ranking 8th), 1-octen-3-ol (9), methyl salicylate (11), acetophenone (13), and conophthorin (25) all elicited fairly strong responses, with ethyl benzoate, methyl salicylate, and conophthorin eliciting higher responses from the female than the male antennae.…”

“…A synthetic blend of host plant volatiles has been recently shown to attract both sexes of navel orangeworm in almond orchards (Beck et al, 2012a); however, this blend, which was based on almond tissue emissions, did not efficaciously attract navel orangeworm in pistachio orchards (Beck & Higbee, 2013;Beck et al, in press). Subsequently, our laboratories have undertaken the task of developing a blend of volatiles attractive to A. transitella in pistachio orchards.…”

Relationship of Almond Kernel Damage Occurrence to Navel Orangeworm (Lepidoptera: Pyralidae) Success

“…Recently, Beck et al (2012) created a host plant volatile blend that included volatiles derived from mechanically damaged almonds. This blend attracted both male and female moths to delta traps (Beck et al 2012).…”

“…Recently, Beck et al (2012) created a host plant volatile blend that included volatiles derived from mechanically damaged almonds. This blend attracted both male and female moths to delta traps (Beck et al 2012). A. transitella females prefer to oviposit on mummy nuts that have been previously infested by conspeciÞcs, which would provide a ready-made entry point (Caltagirone et al 1968, Curtis and Barnes 1977, Andrews and Barnes 1982.…”