Emergence, seasonality, and hybridization of Laricobius nigrinus (Coleoptera: Derodontidae), an introduced predator of hemlock woolly adelgid (Hemiptera: Adelgidae), in the Tennessee Appalachians
| Authors: | Gregory J. Wiggins, Jerome F. Grant, Rusty Rhea, Albert (Bud) Mayfield, Abdul Hakeem, Paris L. Lambdin, A. B. Lamb Galloway |
| Year: | 2016 |
| Type: | Scientific Journal |
| Station: | Southern Research Station |
| DOI: | https://doi.org/10.1093/ee/nvw128 |
| Source: | Environmental Entomology |
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 release
against hemlock woolly adelgid, Adelges tsugae Annand. The shortest emergence period of adult L. nigrinus
was 7 wk beginning 22 October 2010, and the longest emergence was 15 wk beginning 17 October 2012. Native
L. rubidus also were collected from emergence traps placed on the ground surface and beat-sheet samples all
3 yr, with emergence of L. rubidus initiating later than L. nigrinus each season. Seasonality of both Laricobius
species 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 from
emergence traps was significantly greater than the average number of beetles collected from beat-sheet samples
in 2010, while the converse was observed during 2012. Hybridization between L. nigrinus and L. rubidus
was documented from 10.75% of specimens collected during 2010 and 2011, indicating periodic interbreeding
between the introduced and native species. These findings suggest emergence trapping may be a useful
method to assess establishment, population densities, and seasonality of Laricobius species in areas of release
to enhance their use in management of A. tsuage.