Sirex nigricornis

Fabricius, 1781

black-horned woodwasp, native woodwasp

Sirex nigricornis is a North woodwasp ( ) that inhabits pine forests in the eastern United States. Unlike the Sirex noctilio, this primarily attacks stressed, dying, or recently dead pines rather than healthy trees. Females possess a prominent for drilling into wood and along with a symbiotic wood-decaying . The species serves as for multiple including the nematode Deladenus proximus, which sterilizes female eggs, and the Rhyssa howdenorum.

Sirex nigricornis by Natasha Wright. Used under a CC BY 3.0 us license.Sirex nigricornis female by Erich G. Vallery. Used under a CC BY 3.0 us license.Horntail - possibly Sirex nigricornis, Hoffler Creek Preserve, Portsmouth, Virginia - 30765640325 by Judy Gallagher. Used under a CC BY 2.0 license.

Pronunciation

How to pronounce Sirex nigricornis: /ˈsaɪrɛks nɪɡɪˈkɔrnɪs/

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Habitat

Pine forests; specifically associated with shortleaf pine (Pinus echinata) and other pine . Requires wood of appropriate moisture content and decay stage for larval development—freshly cut bolts are preferred for drilling, but 15-day-old bolts are required for successful .

Distribution

to eastern North America; documented from Arkansas, Louisiana, central Louisiana pine forests, and Ontario, Canada.

Host Associations

  • shortleaf pine (Pinus echinata) - for and larval developmentFemales drill into wood to ; larval development requires specific wood aging conditions
  • Deladenus proximus - parasitic nematodeParasitizes and sterilizes in females; rates 16-43% among sites and years
  • Rhyssa howdenorum - ; and period timed to availability in central Louisiana
  • Ibalia leucospoides - Shares olfactory attraction to stressed pine volatiles with ; uses same chemical cues for host location

Life Cycle

with wood-boring larval stage. Females drill into pine bolts using to . Successful development and requires wood bolts seasoned approximately 15 days; freshly cut wood (0-day) is preferred for drilling but does not support successful emergence. Moisture content decreases over seasoning time with majority of loss at bolt ends.

Behavior

Females exhibit strong preference for freshly cut pine bolts, drilling into wood with prominent . This preference is mismatched with developmental requirements—successful only occurs from 15-day-old bolts. attracted to olfactory stimulants from stressed and -colonized pines, including oxygenated monoterpenes (verbenone, fenchone, terpinen-4-ol) and bark beetle (frontalin, endo-brevicomin, ipsenol, ipsdienol). Males are more frequently parasitized by nematodes than females when emerging from the same trees.

Ecological Role

Wood-borer that accelerates decomposition of stressed and dying pines; of wood-decaying symbiotic . Serves as for multiple and parasitic nematodes, contributing to forest complexity. influenced by -dependent .

Human Relevance

Not considered a pest of healthy trees; targets already compromised pines. Distinguished from Sirex noctilio which attacks healthy trees. Research subject for development of lures based on olfactory attraction to stressed pine volatiles.

Similar Taxa

  • Sirex noctilio ; S. nigricornis is and primarily attacks stressed/dying pines while S. noctilio attacks healthy trees
  • Tremex columbaAnother woodwasp with similar cigar-shaped body and prominent , but different tree associations (hardwoods vs. pines)

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