Thanasimus dubius (Fabricius, 1776)

Chapman, Eric G., Leavengood, John M. & Dupuis, Julian R., 2025, The Cleridae and Thanerocleridae of eastern North America, with illustrated keys, updated distributions, and special emphasis on the Kentucky fauna, Zootaxa 5639 (1), pp. 1-88 : 66-67

Thanasimus dubius (Fabricius, 1776) ; Cleridae : Clerinae : Clerini

Illustrations: Plate 5-E. Key to clerid genera, couplet 16-D; Thanasimus key, couplet 1-C, couplet 2-A

Distribution: South FL to NB to SK to ID to NM and Mexico.

- Recorded from: AL, CO, ID, FL, GA, IL, IN, KS, KY, LA, MA, MD, ME, MI, MN, MS, NC, NE, NH, NJ, NM, NY, OK, PA, SC, TN, TX, VA, VT, WV, WI, New Brunswick, Newfoundland, Nova Scotia, Ontario,

Quebec, Saskatchewan, and Mexico ( Wolcott 1909 1947; Papp 1960; Barr 1975; Downie & Arnett 1996; Majka 2006; BugGuide).

- New State Record: KENTUCKY: Owsley, 1.6 mi NW Bonneville, Lindgren funnel trap, trap baited w/ a- & b-pinene, 2-IX-10, Shelby Stamper (EGC-CRC, 1). Due to its common collection during semiochemical and forestry-related studies, which are quite numerous, the authors fear that some distributional records may have been overlooked herein.

Kentucky counties (Map 32): Owsley (1). The lone Kentucky specimen was collected in the Western Allegheny Plateau ecoregion .

Years: 2010 (1)

Months: September (1)

Collections (1): EGC-CRC (1)

Collection methods: Lindgren funnel trap (1)

Natural History: Bøving & Champlain (1920) reported that this species preys on scolytines in the genera Dendroctonus , Ips , and Polygraphus and the weevil Pissodes in conifers, primarily pine ( Pinus ) and spruce ( Picea ). Knull (1951) added that it preys on scolytines in elm ( Ulmus ). Dixon & Payne (1979) reported that adult and larvae of T. dubius prey on all life stages of the southern pine beetle (SPB; Dendroctonus frontalis Zimmerman ), maintaining a high level of spatial and temporal coincidence with SPB populations. The latter observation was also observed by Turchin et al. (1999) who reported that T. dubius densities oscillate with those of the SPB with a slight lag, i.e., their abundance peaks as SPB populations are declining. In lab rearings, Kanaskie et al. (2023) observed that adult T. dubius consume up to 20 adult SPB/day and a single T. dubius larva can consume over 100 immatures (eggs, larvae, pupae) SPB during its development. Multiple papers have been published examining the efficacy of using T. dubius in biological control programs against SPB (e.g., Reeve et al. 2003; Arnaud & Reeve 2012) and the eastern 5-spined engraver Ips grandicollis ( Lawson & Morgan 1992) . Mawdsley (1999) reported that females oviposit in in bark crevices and adults often hide beneath loose bark or bark scales. Leavengood (2008b), citing label data, reported collections via Malaise traps and from slash pine ( Pinus elliottii ) in Florida. Dorshorst & Young (2008) reported that it was common on pine logs ( Pinus spp. ), specifically noting collections from red pine ( Pinus resinosa ) and rearings from white pine ( Pinus strobus ) in Wisconsin. They noted that it was commonly collected with Lindgren funnel traps in woodlands with jack ( Pinus banksiana ), red, and white pines and spruce ( Picea ), was often observed on the bark of bark beetle-infested trees and was abundant in lumber mills.

Chemical lures: Frontalin ( Vite & Williamson 1970); frontalin + alpha-pinene ( Baker et al. 1977); alpha- and beta-pinene ( Mizell et al. 1984); monoterpine blend (alpha- and beta-pinene, myrcene, limonene, camphene and carene) + ethanol ( Chenier & Philogene 1989); various enantiomeric blends of ipsdienol ( Herms et al. 1991, Dorshorst & Young 2008); pityol + alpha-pinene ( de Groot & Debarr 2000); racemic alpha-pinene + ipsdienol + lanierone (Erbilgin et al. 2003); frontalin + alpha-pinene ( Aukema & Raffa 2005); ipsenol or ipsenol + cis-verbenol ( Allison et al. 2013).