Green leaf volatiles disrupt and enhance response to aggregation pheromones by the ambrosia beetle, Gnathotrichus sulcatus (Coleoptera: Scolytidae)

Abstract

Experiments were conducted to test the hypothesis that green leaf volatiles (GLVs) abundant in herbaceous plants and angiosperm trees, affect the response by the conifer-infesting ambrosia beetle, Gnathotrichus sulcatus (LeConte), to pheromone-baited multiple-funnel traps. A blend of four green leaf alcohols, 1-hexanol, (E)-2-hexen-1-ol, (Z)-2-hexen-1-ol, and (Z)-3-hexen-1-ol, each released at ca. 4 mg/24 h, combined with a blend of two green leaf aldehydes, hexanal and (E)-2-hexenal, each released at ca. 13 mg/24 h, reduced trap catches to levels no different from those to unbaited control traps for both sexes. Release of the green leaf alcohols, alone or in all possible binary and ternary blends revealed additive rather than synergistic disruptive effects. Only (E)-2-hexen-1-ol was active alone. Binary and ternary blends reduced trap catches 60-88%, and 80-93%, respectively. No blend was superior, demonstrating redundancy in the disruptive effect. Released together, the two green leaf aldehydes enhanced trap catches; (E)-2-hexenal alone caused a weak enhancement. A summary of known responses by 11 scolytids to GLVs revealed variations between and within species in bioactive compounds and their effect. Disruptive GLVs offer promise alone or with other compounds as forest product protectants against ambrosia beetles.

A survey of antennal responses by five species of coniferophagous bark beetles (Coleoptera: Scolytidae) to bark volatiles of six species of angiosperm trees

“…Conophthorin was also detected in European birches (Byers et al 1998). Portions of nonhosts (Schroeder 1992), as well as individual chemicals, or blends of chemicals known to occur in angiosperm tissues were active in disrupting the response of coniferophagous bark and ambrosia beetles to their aggregation pheromones Borden et al 1997;Byers et al 1998;Deglow & Borden 1998a,b), to host kairomones (Poland & Haack 2000), or to host kairomone/aggregation pheromone mixtures Wilson et al 1996;Borden et al 1998;Deglow & Borden 1998b;Poland et al 1998;Huber et al 1999).…”

Comparative Behavioural Responses ofDryocoetes confususSwaine,Dendroctonus rufipennis(Kirby), andDendroctonus ponderosaeHopkins (Coleoptera: Scolytidae) to Angiosperm Tree Bark Volatiles

“…A growing number of scolytid species have been shown to avoid attractant-baited traps or host trees when a variety of angiosperm bark or leaf volatiles are present (Dickens et al 1992, Schroeder 1992, Schlyter et al 1995, Wilson et al 1996, Guerrero et al 1997, Byers et al 1998, Deglow and Borden 1998a, b, Poland et al 1998, Huber et al 1999, 2000a, Zhang et al 1999, Poland and Haack 2000, Huber 2001, Huber and Borden 2001a. Many of these studies tested potentially disruptive compounds based on previous Þndings with other insects, but no study on the MPB, SB, or the WBBB has tested the full range of potentially behaviorally active NHVs established by coupled gas chromatographic-electroantennographic detection analysis (GC-EAD) (Gries 1995).…”

GC-EAD responses to semiochemicals by eight beetles in the subcortical community associated with Monterey pine trees in coastal California: similarities and disparities across three trophic levels

“…1A). The behavioral activity of these EAD-active compounds in G. retusus remains to be explored, except that EAD-active GLVs (C 6 -alcohols) interrupted attraction to pheromonebaited traps (Deglow & Borden 1998). (-)-Verbenone has been shown to inhibit the attraction to semiochemicals in over 10 species of bark beetles (Borden 1997).…”

“…Similarly, what is known of the chemical ecology of E. sphegeus has also been learned from other forest ecosystems Lindgren & Miller 2002); to our knowledge the chemical ecology of L. tuberculatus has not been investigated. No EAD response data to semiochemicals are available for any of these beetle species; however, nonhost green leaf volatiles (mainly C 6 -alcohols) have been reported to disrupt the flight response of G. retusus to pheromonebaited traps (Deglow & Borden 1998).…”