Emergence, seasonality, and hybridization of Laricobius nigrinus (Coleoptera: Derodontidae), an introduced predator of hemlock woolly adelgid (Hemiptera: Adelgidae), in the Tennessee Appalachians

Abstract

From 2010 through 2013, adult emergence and seasonality of Laricobius nigrinus Fender, an introduced predatoryspecies native to western North America, as well as hybridization with the native species Laricobius rubidus(LeConte), were evaluated using emergence traps and beat-sheet sampling in areas of previous releaseagainst hemlock woolly adelgid, Adelges tsugae Annand. The shortest emergence period of adult L. nigrinuswas 7 wk beginning 22 October 2010, and the longest emergence was 15 wk beginning 17 October 2012. NativeL. rubidus also were collected from emergence traps placed on the ground surface and beat-sheet samples all3 yr, with emergence of L. rubidus initiating later than L. nigrinus each season. Seasonality of both Laricobiusspecies was similar across a 44-mo study period. Adult L. nigrinus were present from October through April,and larvae of Laricobius spp. were collected from February to May. The average number of L. nigrinus fromemergence traps was significantly greater than the average number of beetles collected from beat-sheet samplesin 2010, while the converse was observed during 2012. Hybridization between L. nigrinus and L. rubiduswas documented from 10.75% of specimens collected during 2010 and 2011, indicating periodic interbreedingbetween the introduced and native species. These findings suggest emergence trapping may be a usefulmethod to assess establishment, population densities, and seasonality of Laricobius species in areas of releaseto enhance their use in management of A. tsuage.

Citation

Wiggins, Gregory J.; Grant, Jerome F.; Rhea, James R.; Mayfield, Albert E.; Hakeem, Abdul; Lambdin, Paris L.; Galloway, A. B. Lamb. 2016. Emergence, seasonality, and hybridization of Laricobius nigrinus (Coleoptera: Derodontidae), an introduced predator of hemlock woolly adelgid (Hemiptera: Adelgidae), in the Tennessee Appalachians . Environmental Entomology, Vol. 45(6): 8 pages.: 1371-1378. doi: 10.1093/ee/nvw128