Canadian Forest Service Publications
First report of mating disruption with an aggregation pheromone: a case study with Tetropium fuscum (Coleoptera: Cereambycidae). Sweeney, J.D.; Silk, P.J.; Rhainds, M.; MacKay, W.; Hughes, C.; Van Rooyen, K.; MacKinnon, W.; Leclair, G.; Holmes, S.E.; Kettela, E.G. 2017. Journal of Economic Entomology 110(3): 1078-1086.
Issued by: Atlantic Forestry Centre
Catalog ID: 39129
Availability: PDF (download)
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Tetropium fuscum (F.), native to Europe and established in Nova Scotia, Canada, since at least 1990, is considered a low-to-moderate threat to spruce (Picea spp.) forests in North America and regulated as a quarantine pest by the Canadian Food Inspection Agency. We tested broadcast applications of the aggregation pheromone racemic (5E)-6,10-dimethyl-5,9-undecadien-2-ol (fuscumol), formulated at 10% concentration in Hercon Bio- Flakes (Hercon International, Emigsville, PA), for efficacy in disrupting T. fuscum mating and suppressing populations. Two applications of 2.5–2.75 kg Bio-Flakes (250–275 g a.i.) per ha per season significantly reduced trap catches and mating success (2009, 2010, 2012): about 30% of females trapped in treated plots had mated compared with 60% of females trapped in untreated plots. Similar reductions in mating success were observed in 2011 with one or two 4.5 kg/ha applications of Bio-Flakes. Mean densities of T. fuscum colonizing sentinel bait logs or girdled trees were 36% lower in pheromone-treated plots than in untreated plots, but the difference was not statistically significant. Lack of population suppression may have been because mated females immigrated into treated plots or because populations were so high that despite a 50% reduction in mating success, absolute numbers of mated females were sufficient to infest our bait logs or trees. This is the first demonstration of insect mating disruption via broadcast application of an aggregation pheromone. Pheromone-mediated mating disruption has potential to slow the spread of invasive cerambycids by targeting low-density outlier populations near or beyond the leading edge of an infestation.
Plain Language Summary
The brown spruce longhorned beetle (BSLB)—established in Nova Scotia, Canada, since at least 1990—is considered a low to moderate threat to mature spruce (Picea spp.) forests in North America and is regulated as a quarantine pest by the Canadian Food Inspection Agency in an effort to slow its spread. Our study tested the effectiveness of “pheromone-mediated mating disruption” as a means of controlling BSLB and slowing its spread in North America. Pheromones are chemicals that an insect emits to either attract the opposite sex (sex pheromones) or both sexes (aggregation pheromones) of the same species to increase the success of mating, colonization of suitable host plants, etc. Broadcast application of sex pheromone has successfully controlled populations of pests like the gypsy moth, by disrupting normal response of males to pheromone-emitting females, thus reducing mating success and fertile egg production. Male BSLB emit an aggregation pheromone called fuscumol that synergizes attraction of both males and females to the odors from stressed spruce trees. We tested aerial applications of fuscumol in biodegradable Hercon BioFlakes® in forest field trials from 2008–2012 and measured its effect on BSLB mating success as well as infestation levels. Two pheromone applications per season reduced mating success by 50%: only 30% of females were found mated in treated plots compared with 60% in untreated plots. The effect on infestation levels was variable, however, with no significant reduction of BSLB densities in treated plots. Lack of population suppression in treated plots may have been because mated females immigrated into our treated plots or because T. fuscum populations were too high in our test sites. Theory predicts that pheromone-based mating disruption works best in low-density populations where competition with naturally emitting insects is lower. This is the first demonstration of insect mating disruption via broadcast application of an aggregation pheromone. Our results suggest that fuscumol applications have potential as a tactic to slow the spread of BSLB if targeted at low density outlier populations that lie near or beyond the leading edge of an infestation.