Subterranean survivorship and seasonal emergence of laricobius spp. (Coleoptera: Derodontidae), biological control agents for the hemlock woolly adelgid.

  • Authors: Foley, Jeremiah; McAvoy, Thomas; Grubb, Christopher; Mayfield, Albert; Strahm, Brian; Salom, Scott M.
  • Publication Year: 2021
  • Publication Series: Scientific Journal (JRNL)
  • Source: Environmental Entomology
  • DOI: 10.1093/ee/nvab124


Following the adventive arrival, subsequent spread, and ensuing impact of Adelges tsugae Annand (Hemiptera:
Adelgidae), the hemlock woolly adelgid (HWA) in the eastern United States, a robust initiative was launched with the
goal of decreasing ecosystem impacts from the loss of eastern hemlock (Pinales: Pinaceae). This initiative includes
the use of biological control agents, including Laricobius spp. (Insecta: Coleoptera). Laboratory production of these
agents is limited by subterranean mortality and early emergence. Therefore, the subterranean survivorship and
timing of emergence of a mixture of Laricobius spp. was investigated. PVC traps internally lined with a sticky card
and covered with a mesh screen were inserted into the soil to measure the percent emergence of adults based on the
number of larvae placed within. The number of emerged adults in the field and laboratory-reared larval treatments
was adjusted based on emergence numbers in the control and used as the response variable. Independent variables
included in the final model were: treatment (field-collected vs. laboratory-reared), organic layer depth (cm), soil pH,
and April-to-December mean soil moisture. No differences were found in survivorship between field-collected and
laboratory-reared treatments. As pH and organic layer increased survivorship decreased, significantly. Although
the majority of emergence occurred in the fall, emergence also occurred in spring and summer. The occurrence of
spring and summer emergence and low survivorship (17.1 ± 0.4%) in the field across all treatments suggests that
these are characteristics of Laricobius spp. field biology in their introduced range and not artifacts of the laboratory
rearing process.

  • Citation: Foley, Jeremiah R; McAvoy, Thomas J; Grubb, Christopher; Mayfield, Albert E; Strahm, Brian; Salom, Scott M. 2021. Subterranean survivorship and seasonal emergence of Laricobius spp. (Coleoptera: Derodontidae), biological control agents for the hemlock woolly adelgid . Environmental Entomology. 51(1): 63-70.
  • Keywords: predator, IPM, invasive species
  • Posted Date: March 16, 2022
  • Modified Date: March 17, 2022
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