Range of Attraction of Pheromone Lures and Dispersal Behavior of Cerambycid Beetles

Annals of the Entomological Society of America, 109(6), 2016, 872–880 doi: 10.1093/aesa/saw055 Advance Access Publication Date: 6 August 2016 Ecology and Population Biology Research article Range of Attraction of Pheromone Lures and Dispersal Behavior of Cerambycid Beetles E. Dunn,1,2 J. Hough-Goldstein,1 L. M. Hanks,3 J. G. Millar,4 and V. D’Amico5 1Department of Entomology and Wildlife Ecology, University of Delaware, 531 S. College Ave., Newark, DE 19716 ([email protected]; [email protected]), 2Corresponding author, e-mail: [email protected], 3Department of Entomology, University of Illinois at Urbana-Champaign, 505 S. Goodwin Ave. MC-118, Urbana, IL 61801 ([email protected]), 4Department of Entomology, University of California, 900 University Ave., Riverside, CA 92521 ([email protected]), and 5U. S. Forest Service, Northern Research Station, 531 S. College Ave., Newark, DE 19716 ([email protected]) Received 13 April 2016; Accepted 12 July 2016 Abstract Cerambycid beetles (Coleoptera: Cerambycidae) can locate suitable hosts and mates by sensing pheromones and plant volatiles. Many cerambycid pheromone components have been identified and are now produced syn- thetically for trap lures. The range over which these lures attract cerambycids within a forest, and the tendency for cerambycids to move out of a forest in response to lures, have not been explored previously. We conducted two field experiments using baited and unbaited panel traps in northern Delaware to investigate these ques- tions. Within forest fragments, unbaited traps that were 2 m from a baited trap captured more beetles than unbaited control traps, suggesting increased cerambycid activity leading to more by-catch in unbaited traps at 2 m from the pheromone source. Traps at further distances from a baited trap did not catch significantly more beetles than equivalent controls. In contrast, male Prionus laticollis (Drury), which were attracted by the likely female-produced sex pheromone 3,5-dimethyldodecanoic acid, were rarely collected in unbaited traps at any distance from baited traps. Outside the forest, baited traps attracted significantly more cerambycids than unbaited traps at distances up to 40 m from the forest edge, with catch generally decreasing between 8 and 40 m from the forest. Some cerambycids were collected in both baited and unbaited traps at all distances from the forest edge, indicating that at least some species dispersed out of the forest independent of any pheromonal at- tractants. Our results provide context to previous studies that used these pheromone lures, and offer insights into cerambycid dispersal behavior. Key words: Cerambycidae, movement, forest fragmentation, Xylotrechus colonus, Prionus laticollis Longhorned beetles (Cerambycidae) are often abundant and diverse sex pheromones likely serve as the primary attractant for males in North American forest ecosystems, with 1,100 species in North (Millar and Hanks 2016). America and >35,000 described species worldwide (Yanega 1996, Male-produced aggregation pheromones have been identified for Sv acha and Lawrence 2014). Larvae of most cerambycid species a number of cerambycid species, and synthesized for use as baits in feed within dead wood and aid in decomposition and nutrient cy- traps (e.g., Hanks and Millar 2013, Hanks et al. 2014, Handley cling (Linsley 1959); however, some species infest living trees, cut et al. 2015, Ray et al. 2015, reviewed by Millar and Hanks 2016). timber, or wooden structures, and thus are of economic concern Cerambycid pheromones are often highly conserved among related (Solomon 1995). Larvae typically require 1–3 yr to complete devel- species, with interspecific attraction minimized through temporal opment, overwintering as larvae or prepupae. Adults of most species and phenological isolation (Hanks et al. 2014, Mitchell et al. 2015, emerge over a period of a few to several weeks in spring and summer Millar and Hanks 2016). Pheromones of species in different subfa- (Hanks et al. 2014, Handley et al. 2015). Adults usually live for no milies tend to be of different chemical classes, and in general do not more than one to two months (Yanega 1996). Mate location is often interfere with one another, so that blends of cerambycid pheromone mediated by volatile aggregation pheromones produced by males of components can effectively attract a wide range of species, without species in the subfamilies Cerambycinae, Lamiinae, and substantial inhibition of attraction (e.g., Hanks et al. 2012, Wong Spondylidinae, or female-produced sex pheromones for species in et al. 2012). To further enhance attraction of many cerambycid spe- the subfamilies Prioninae and Lepturinae (reviewed by Millar and cies, plant volatiles (particularly ethanol and a-pinene) can be de- Hanks 2016). Attraction of both sexes to aggregation pheromones ployed with pheromone lures, often resulting in larger and more may be synergized by host plant volatiles, but the female-produced diverse catches than those from pheromone lures alone (Hanks et al. VC The Authors 2016. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For Permissions, please email: [email protected] 872 Annals of the Entomological Society of America, 2016, Vol. 109, No. 6 873 2012, Millar and Hanks 2016). Ethanol is produced by a variety of (De Groot and Nott 2001; McIntosh et al. 2001; Morewood et al. woody plants when stressed (Kimmerer and Kozlowski 1982; Gara 2002; Graham and Poland 2012; Graham et al. 2010, 2012; Allison et al. 1993; Kelsey 1994, Kelsey and Joseph 2003, Kelsey et al. et al. 2016). When baited appropriately, such traps can catch large 2014), and a-pinene is a common plant volatile, particularly from numbers of a diverse array of cerambycids (e.g. Hanks and Millar conifers (Hanks et al. 2012, Millar and Hanks 2016). In previous 2013, Handley et al. 2015, Collignon et al. 2016). studies, ethanol enhanced attraction of some cerambycid species to While such traps are useful to assess diversity and collect species pheromones (Hanks et al. 2012, Hanks and Millar 2013, Handley that could otherwise be difficult to locate, their overall efficacy has et al. 2015, reviewed in Millar and Hanks 2016). Racemic 3,5- yet to be assessed. In particular, the range over which a baited trap dimethyldodecanoic acid (“prionic acid”), a female-produced sex attracts cerambycids generally is not known for male-produced ag- pheromone for a number of species in the genus Prionus (Prioninae), gregation pheromones, and probably varies by species. In addition, can also be included in lures to attract a variety of species within traps without pheromone baits, or baited only with isopropyl alco- that genus (Barbour et al. 2011, Millar and Hanks 2016). hol as a solvent control, do collect some cerambycids (e.g. Handley Research on dispersal of cerambycids has produced varying re- et al. 2015), but it is not known whether nearby pheromone sources sults, likely because of the diverse life histories of species within the increase the incidence of trap catch in unbaited traps. Thus, in our family (Hanks 1999). For example, research on the dispersal of the first experiment, we aimed to more precisely determine the range cerambycine Cerambyx welensii Ku¨ster found that the majority of over which cerambycid activity is affected by a blend of male- adults were sedentary, but dispersed an average of 200 m when they produced aggregation pheromones. Our second experiment sought did move (Torres-Vila et al. 2013). In contrast, the lamiine to gauge the tendency of cerambycids to disperse from forest frag- Monochamus alternatus Hope was found to disperse only up to 37 ments, both in response to pheromones and by random movement. m in a mark–recapture experiment (Togashi 1990). Overall, the This dispersal tendency is especially important in the context of the scale and frequency of dispersal can be widely variable among highly fragmented forests prevalent in the coastal eastern United cerambycid subfamilies and species, and should be assessed on a States, where our research took place. species-by-species basis; studies thus far have only assessed a few species (Holland et al. 2004). In order to use pheromone- and ethanol-baited traps to study Materials and Methods cerambycid dispersal, we must first understand the response of cerambycids to these traps. Whereas a variety of traps have been Study Sites used to catch cerambycids and other saproxylic beetles, among the Study sites were part of the FRAME (Forest Fragments in Managed most effective are intercept designs such as funnel traps and cross- Ecosystems) system, a collaboration between the University of vane panel traps, especially those with a dark silhouette and with Delaware and the U. S. Forest Service that aims to better understand the surface treated with a slippery substance such as Fluon urban and suburban forest fragment dynamics to improve ecosystem 2 m 10 m 20 m N = 4 N = 8 N = 12 Fig. 1. Arrangement of traps for pheromone range experiment in 2014. Traps were positioned in concentric circles around a central trap at distances of 2 m (N ¼ 4), 10 m (N ¼ 8), and 20 m (N ¼ 12). At each site, the central trap of one array was baited with synthetic pheromone, whereas all other traps were unbaited. 874 Annals of the Entomological Society of America, 2016, Vol. 109, No. 6 management (http://sites.udel.edu/frame/, Accessed 22 Jul 2016). The the following compounds: racemic 3-hydroxyhexan-2-one (50 mg/ first experiment was conducted within two FRAME forest fragments lure), 2-(undecyloxy)ethanol (¼ monochamol, 25 mg), racemic (E)- (Folk, N 39.645670 W 75.757717, and Glasgow 1, N 39.610898 6,10-dimethylundeca-5,9-dien-2-ol (fuscumol) and (E)-6,10-dimethy- W 75.726217), and the second was conducted at two other FRAME lundeca-5,9-dien-2-yl acetate (fuscumol acetate; 50 mg each), all from sites (Ecology Woods, N 39.662422 W 75.744392,andGlasgow2, Bedoukian Research (Danbury, CN), syn-2,3-hexanediol (50 mg; syn- N 39.613133 W 75.732901; all in New Castle County, DE).

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