DOI: 10.5061/dryad.tb2rbp01f
title: Using semiochemicals to predict biotic resistance and facilitation of invading phytophagous insects

description: Invasive species are leading causes of biodiversity loss and economic
 damage. Allocating limited resources towards prevention and management of
 invasions requires risk assessments based on ecological knowledge for
 species of potential concern. Interactions of potentially invasive species
 with heterospecifics in a novel community will contribute to biotic
 resistance and facilitation experienced by the invader, and thus the
 likelihood of establishment. To experimentally predict heterospecific
 interactions, we conducted field experiments using synthetic
 aggregation-pheromone lures to measure the response of ecologically
 relevant species (possible predators, competitors, and facilitators) to
 the simulated presence of two potentially invasive spruce bark beetles,
 the North American Dendroctonus rufipennis (tested in Norway) and the
 European Ips typographus (tested in eastern Canada). The Canadian beetle
 community responded strongly to I. typographus lures, suggesting potential
 for considerable biotic resistance, whereas D. rufipennis lures prompted
 little response by the Norwegian beetle community. D. rufipennis was
 attracted to I. typographus lures, suggesting potential facilitation
 between these species through cooperative mass attack on trees. Our
 findings will inform invasive-species risk assessments for I. typographus
 and D. rufipennis and highlight useful methods for assessing interactions
 among other taxa that rely heavily on semiochemical communication.
description: Multiple-funnel traps in
 experimental sites in Canada and Norway were baited with a variety of
 semiochemical dispensers including controls, with the goal of determining
 if relevant heterospecifics (bark beetles and predators thereof) responded
 to the aggregation pheromone blends of two potentially invasive bark
 beetle species, <em>Dendroctonus rufipennis</em> (tested in
 Norway) and <em>Ips typographus</em> (tested in Canada). Both
 experiments were set up as randomized block designs. The experiment in
 Canada had seven replicate blocks, and the experiment in Norway had ten.
 Beetles captured in the traps throughout the spring and summer were IDed
 to species in most cases, though only to genus for some, and
 counted. The Host
 treatments consisted of α-pinene and ethanol (Synergy Semiochemicals
 Corp., Burnaby, BC, Canada). The Ipslure treatments consisted
 of the commercialy available<em> Ips typographus</em> lure
 (methylbutenol, cis-verbenol, and ipsdienol; Ipslure®) plus the host
 volatiles (α-pinene and ethanol). The DRlure treatments consisted
 of the commercially available Atlantic <em>Dendroctonus
 rufipennis</em> lure (frontalin and seudenol; Synergy Semiochemicals
 Corp., Burnaby, BC, Canada), further amended with MCOL, and host volatiles
 (α-pinene and ethanol). The control treatments did not
 have lures or host volatiles.
description: These data are counts of selected beetle taxa captured in
 multiple-funnel traps in New Brunswick, Canada and Ås, Norway. They should
 be analyzed as a randomized block design, with treatment as a fixed effect
 and block number as a random effect.4