Laricobius nigrinus
Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Coleoptera
Family: Derodontidae
Genus: Laricobius
Species:
L. nigrinus
Binomial name
Laricobius nigrinus
Fender, 1945
L. nigrinus larva feeding in an A. tsugae ovisac

Laricobius nigrinus is a species of tooth-necked fungus beetle in the family Derodontidae.[1][2] It is native to western North America, and it is being studied as a biological control agent for the hemlock woolly adelgid.[3] It was first released in 2003 and continues to be reared and released across the Northeast to control infestations.[4]

Taxonomy

Laricobius nigrinus was first described by Kenneth Fender in 1945 from specimens collected in Oregon.[5] Laricobius is one of four genera in Derodontidae.[6] The genus has a Holarctic distribution, with most species native to Asia.[6]

Description

Adult beetles have a black body, clubbed antennae with eleven segments, and two ocelli. Their palps, antennae, and tarsi are dark brown to red. The head is partially visible from above.[7] They are usually 2.3-2.9 mm long, with no significant sex differences in size.[7] The species can be distinguished from other black Laricobius by its toothed pronotal margin.[6] Its eggs are yellow and oblong, usually laid in the ovisacs of A. tsugae.[7] The larvae have three segmented antennae, a well-developed head with twelve stemmata and hairy abdominal segments.[7] They are "oligopod type" larvae, with three pairs of thoracic legs, and no prolegs. The larvae start as yellow before darkening to yellow green/yellow brown with maturity. Pupae resemble the adult form, and individuals can be sexed in pupal form.[7]

Habitat, life cycle and behavior

All members of Laricobius feed on members of Adelgidae, and Laricobius nigrinus is specialized on the hemlock woolly adelgid.[7] The predatory life history of Laricobius is unique among the family as most derodontids are fungal feeders.[6] L. nigrinus is native to hemlock forests in the Pacific Northwest. It can be found throughout the western U.S. and Canada, and specimens in the U.S. Museum of Natural History have been collected as far north as the southeastern Yukon.[8] It has a univoltine life cycle, completing one generation per year. Eggs are laid in early spring, and its development is synchronized with the winter/spring generation of A. tsugae.[8] Females lay an average of 100 eggs during their lifetimes.[9] L. nigrinus goes through four larval instars, and the larvae use secretions to glue debris and adelgid wool to themselves as camouflage.[7] Fourth instar larvae drop to the ground as prepupae and complete their development in the soil before emerging as adults in the fall. Similar to its prey, L. nigrinus is dormant during the summer months, aestivating as a pupa. The adult beetles feed on adult adelgids, while the larvae feed on the eggs of the spring progrediens generation.[8] They have a temperature dependent development, and cannot complete development above 21 °C.[10] They are significantly more active during the day than at night. Their flight behavior is responsive to prey densities, and they will only fly when their food source is scarce.[11] They use scent to home in on adelgids at close range, and respond to the odors of the adelgid's native host tree, western hemlock as well as the odors of western white pine and white spruce.[12]

Biological control

Due to its narrow prey specificity and geographic range, L. nigrinus was approved by USDA-APHIS for release as a biological control agent in 2000.[8] Field releases began in 2003, and populations have expanded to cover a wide range of A. tsugae infestation.[8] As of 2021 it has been released in 18 states, and has established in Pennsylvania, Maryland, New York, New Jersey, Virginia, Georgia, West Virginia, North Carolina, Tennessee, Connecticut, Massachusetts, Maine, and New Hampshire. Releases are continuing throughout the infestation range.[13][4] It has been shown to strongly impact A. tsugae densities in experiments conducted in their native range,[14] and a recent study found that L. nigrinus has a significant impact on the mortality of A. tsugae eggs at caged release sites.[15] Studies are ongoing to determine the rate of hybridization between L. nigrinus and its native congener, Laricobius rubidus which feeds on pine bark adelgid.[16]

References

  1. ↑ "ITIS - Report: Laricobius nigrinus". www.itis.gov. Retrieved 2021-10-20.
  2. ↑ "Laricobius nigrinus Fender, 1945". www.gbif.org. Retrieved 2021-10-20.
  3. ↑ "eLibrary Redirect - DEP eLibrary" (PDF). www.docs.dcnr.pa.gov. Retrieved 2021-10-20.
  4. 1 2 Limbu, S; Keena, M A; Whitmore, M C (2018-01-01). "Hemlock Woolly Adelgid (Hemiptera: Adelgidae): A Non-Native Pest of Hemlocks in Eastern North America". Journal of Integrated Pest Management. 9 (1). doi:10.1093/jipm/pmy018. ISSN 2155-7470.
  5. ↑ Fender, K.M. (1945). "A new Laricobius from Oregon (Coleoptera:Derodontidae)". Pan-Pacific Entomologist. 21: 152.
  6. 1 2 3 4 Leschen, Richard a. B. (2011-06-07). "World review of Laricobius (Coleoptera: Derodontidae)". Zootaxa. 2908 (1): 1–44–1–44. doi:10.11646/zootaxa.2908.1.1. ISSN 1175-5334.
  7. 1 2 3 4 5 6 7 Zilahi-Balogh, G. M. G.; Humble, L. M.; Kok, L. T.; Salom, S. M. (October 2006). "Morphology of Laricobius nigrinus (Coleoptera: Derodontidae), a predator of the hemlock woolly adelgid". The Canadian Entomologist. 138 (5): 595–601. doi:10.4039/n05-096. ISSN 1918-3240. S2CID 84505865.
  8. 1 2 3 4 5 Mausel, D. L., Davis, G. A., Lamb, A. S., Zilahi-Balogh, G. M. G., Kok, L. T., & Salom, S. M. (2011). Laricobius nigrinus Fender (Coleoptera: Derodontidae). ImplementatIon and StatuS of BIologIcal control of the hemlock Woolly adelgId, 77.
  9. ↑ Zilahi-Balogh, G.M.G.; Salom, S.M.; Kok, L.T. (2003-06-01). "Development and reproductive biology of Laricobius nigrinus, a potential biological control agent of Adelges tsugae". BioControl. 48 (3): 293–306. doi:10.1023/A:1023613008271. ISSN 1573-8248. S2CID 7471225.
  10. ↑ Zilahi-Balogh, G. M. G.; Salom, S. M.; Kok, L. T. (2003-12-01). "Temperature-Dependent Development of the Specialist Predator Laricobius nigrinus (Coleoptera: Derodontidae)". Environmental Entomology. 32 (6): 1322–1328. doi:10.1603/0046-225x-32.6.1322. ISSN 0046-225X.
  11. ↑ Mausel, D.L.; Salom, S.M.; Kok, L.T. (August 2011). "Visual Ability and Searching Behavior of AdultLaricobius nigrinus, a Hemlock Woolly Adelgid Predator". Journal of Insect Science. 11 (111): 111. doi:10.1673/031.011.11101. ISSN 1536-2442. PMC 3281397. PMID 22220637.
  12. ↑ Wallin, Kimberly F.; Latty, Tanya M.; Ross, Darrell W. (2011-08-01). "Orientation Behavior of the PredatorLaricobius nigrinus(Coleoptera: Derodontidae) to Hemlock Woolly Adelgid and Host Tree Odors in a Multi-Chambered Olfactometer". Environmental Entomology. 40 (4): 864–872. doi:10.1603/en10287. ISSN 0046-225X. PMID 22251687.
  13. ↑ Dodd, Denise. "Maps and Charts – HWA Predator Database". Retrieved 2021-11-02.
  14. ↑ Mausel, D. L.; Kok, L. T.; Salom, S. M. (2017-04-21). "Numerical Response and Impact of Laricobius nigrinus (Coleoptera: Derodontidae) on Adelges tsugae (Hemiptera: Adelgidae) in Their Native Range". Environmental Entomology. 46 (3): 544–551. doi:10.1093/ee/nvx078. ISSN 0046-225X. PMID 28444212.
  15. ↑ Jubb, Carrie S.; Heminger, Ariel R.; Mayfield, Albert E.; Elkinton, Joseph S.; Wiggins, Gregory J.; Grant, Jerome F.; Lombardo, Jeffrey A.; McAvoy, Thomas J.; Crandall, Ryan S.; Salom, Scott M. (2020-04-01). "Impact of the introduced predator, Laricobius nigrinus, on ovisacs of the overwintering generation of hemlock woolly adelgid in the eastern United States". Biological Control. 143: 104180. doi:10.1016/j.biocontrol.2019.104180. hdl:10919/102744. ISSN 1049-9644. S2CID 213522588.
  16. ↑ Fischer, Melissa J.; Havill, Nathan P.; Brewster, Carlyle C.; Davis, Gina A.; Salom, Scott M.; Kok, Loke T. (2015-03-01). "Field assessment of hybridization between Laricobius nigrinus and L. rubidus, predators of Adelgidae". Biological Control. 82: 1–6. doi:10.1016/j.biocontrol.2014.12.002. ISSN 1049-9644.

Further reading

  • Lobl, I.; Smetana, A., eds. (2007). Catalogue of Palaearctic Coleoptera, Volume 4: Elateroidea - Derodontoidea - Bostrichoidea - Lymexyloidea - Cleroidea - Cucujoidea. Apollo Books. ISBN 978-8788757675.
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