SREF-FH-003 June 2016

woodwasp has not become a major The woodwasp, Sirex noctilio: pest in may be the Ecology, Potential Impact, and Management in the Southeastern U.S. many that are competitors or natural enemies. Some of these insects compete for resources AUTHORED BY: LAUREL J. HAAVIK AND DAVID R. COYLE (e.g. native woodwasps, and ambrosia beetles, and longhorned beetles) while others (e.g.parasitoids) are natural enemies and use larvae as hosts. However, should the Sirex woodwasp arrive in the southeastern U.S., with its abundant plantations and areas of natural pine, this could easily be a major pest for the region.

Researchers have monitored and tracked Sirex woodwasp populations since its discovery in North America. The most common detection tool is a flight intercept trap (Fig. 2a) baited with a synthetic chemical lure that consists of pine scents (70% α-pinene, 30% β-pinene) or actual pine branches (Fig. 2b). Woodwasps are attracted to the odors given off by the lure or cut pine branches, and as they fly toward the scent they collide with the sides of the trap and drop Figure 1. The high density of likely or confirmed pine( Pinus spp.) hosts of the Sirex woodwasp suggests the southeastern U.S. may be heavily impacted should this non-native insect become into the collection cup at the bottom. established in this region. The collection cup is usually filled with a liquid (e.g. propylene glycol) that acts as both a killing agent and Overview and Detection preservative that holds the insects until they are collected. While the The Sirex woodwasp (Sirex noctilio F.) is a large, non-stinging that traps are somewhat effective, there is colonizes and kills stressed pine trees. This insect, originally from Eurasia, is still work to be done to improve our not considered a pest in its native range. However, it has become a major trapping methodology and efficiency. pest in some countries in the Southern Hemisphere (such as and Another monitoring technique is the ), where it was accidentally introduced. It has infested areas with use of a log cut from a live tree. This thousands of acres of planted pine in commercial plantations. So far, the Sirex log, left outside, attracts female Sirex woodwasp has not become a major pest in North America, and is found only woodwasps, who then lay eggs in in , Ohio, , , Vermont, and Connecticut, and the the log. The log can then be placed Canadian provinces of Ontario and Quebec. However, considering the large in a cage, and adult woodwasps can amount of favorable habitat that exists in the southeastern U.S. (Fig. 1), great be captured and recorded as they potential for damage from the Sirex woodwasp exists. One reason the Sirex emerge from the log.

www.southernforesthealth. 1 a b a c by a professional. Please see the a Host Trees “Resources” section at the end of this document for help in identifying a All hard in the southeastern local forest health professional. U.S. are either confirmed or likely hosts for the Sirex woodwasp (Table 1), which also rarely attacks Life Cycle , , and larch15. This insect prefers pines with a diameter of 6” Development from egg to adult is 1-3 and larger, though it will attack trees years, but one year is expected in the <2” in diameter. Native pines in the b d southeastern U.S. Adults emerge in b southeastern U.S. appear to vary mid to late summer (July – August), in their susceptibility to the Sirex Figure 2. Panel intercept trap (available from only live for up to two weeks, and do Alpha Scents, Inc.: http://www.alphascents. woodwasp based on laboratory not feed – using their energy instead com/traps/traps.html) hung between two pine experiments2,6, and two pine species trees, equipped with a Sirex lure (blue bag, to reproduce13. Females drill tiny common in the Southeast – loblolly A; available from Contech Enterprises, Inc.: holes into the wood where they first https://www.contech-inc.com/) or bag of fresh and slash – are known hosts for the test the suitability of the tree (Fig. pine material (B) and collection cup (white) Sirex woodwasp in other parts of containing preservative (propylene glycol). Figure 3. Sirex woodwasp female (A, B) and male (C, D). 5). If the tree is suitable, females will the world. In some parts of , deposit eggs, inject a toxic mucus, up to 70% damage was recorded and inoculate a symbiotic . in some stands12. Thus, there is a c e g The mucus helps stress trees, while potential for widespread damage on Wasp Identifi- the fungus helps larvae digest and southeastern host trees. extract nutrients from the wood3,4,16. Adults have a black to metallic-blue Larvae can eat the fungus, and the head, black antennae, and range fungus also helps break down the Host Tree Con- from ½” – 1½” in length. Adult wood and make it easier for larvae females have black bodies with to digest. Sirex woodwasp larvae are The European woodwasp usually orange legs, and adult males are cream-colored, legless, and have a attacks trees that are already under b d f h mostly black with an orange band spine at the tip of the abdomen (Fig. some sort of stress. These stressors can across the abdomen, and black 6A). Larvae chew through the wood, include drought, poor management, hind legs (Fig. 3). All adults have a creating and enlarging meandering Figure 6. Sirex woodwasp (A) and competitive stand conditions (e.g. pointed spine-like projection (called a tunnels as they grow (Fig. 6B). Larvae damage (B). cornus) at the end of their abdomen. consume both wood and the fungus Females have another appendage at deposited by the female. Larvae Table 1. Host use by the European woodwasp on native pines in the southeastern U.S the end of their abdomen, called an overwinter inside their tunnels, ovipositor, which is used to drill into pupate in early summer, and exit trees Common name Scientific name Likely susceptibility? Confirmed as host? i k m wood to lay eggs. The southeastern as adults in mid- to late summer13. U.S. is home to several species of Loblolly pine Very high Yes native woodwasps, many of which Shortleaf pine Pinus echinata High Yes look similar to the Sirex woodwasp Slash pine Pinus elliottii High Yes (Fig. 4). Even among individuals within a species, there can be a lot of Virginia pine Pinus virginiana High Yes variation in appearance and size. For Pinus palustris Medium Yes instance, females of the woodwasp j l n Sirex nigricornis (Fig. 4M and N), Pitch pine Pinus rigida Medium Unknown which is native to North America, can Pond pine Pinus serotina Medium Unknown have a black or reddish abdomen, and males (which are uncommon, Sand pine Pinus clausa Medium Unknown and rarely captured in traps) may Spruce pine Pinus glabra Medium Unknown have a yellow stripe or entirely yellow abdomen. Because of these Table mountain pine Pinus pungens Medium Unknown Figure 4. Woodwasps similar in appearance to the Sirex woodwasp, Sirex noctilio: Sirex cyane- similarities with different species and Eastern white pine Pinus strobus Low Yes us female (A) and male (B), Eriotremex formosanus female (C) and male (D), taxodii different color patterns, if you think female (E) and male (F), U. cressoni female (G) and male (H), U. albicornis female (I) and male (J), columba female (K) and male (L), and S. nigricornis female (M) and male (N). Erio- you’ve found a Sirex woodwasp, it is Figure 5. Dead female Sirex woodwasp with References: 6, 14, 15, and the USDA FS FHTET Steering Committee tremex formosanus, like S. noctilio, is not native to the U.S. very important to have it identified ovipositor stuck in the tree. (http://www.fs.fed.us/foresthealth/technology/pdfs/host_species_susceptibility.pdf)

www.southernforesthealth. 2 www.southernforesthealth.net/ 3 suppressed or overtopped trees), emergence holes - both types of (Fig. 10) and potential competitors genetically inferior trees, or other pest holes overlap in size with emergence of native woodwasps, and experts infestations. Healthy, dominant pines holes of other insects, such as parasit- believe these insects may help, in are infrequently attacked, and very oids of woodwasps, and other wood part, to limit Sirex woodwasp popula- unthinned thinned infrequently killed 8,11. borers, who also tend to live in dead tions. Several parasitoid native and dying trees and have a similar to North America attack the Sirex life cycle (i.e. immatures develop woodwasp5. In some cases, these Infestation Diagno- in wood, adults chew their way out parasitoids have caused substantial when they emerge). mortality to Sirex woodwasp popula- Affected trees can be identified by tions5, and would likely be important several characteristics. Often, the components of an integrated pest most noticeable is beads of resin Forest Manage- management program. Parasitic that run down the trunk of the tree species have been ef- (Fig. 7). This is the tree’s response to The southeastern U.S. has many of fective in managing populations of females drilling into the tree to test the characteristics that make for ex- Sirex woodwasp in several Southern it for suitability. Once the eggs hatch cellent Sirex woodwasp habitat. Large Hemisphere countries and show and larvae start feeding in the wood, areas of preferred host trees (pines), some potential in North America10. needles begin to wilt and change to coupled with a mild climate and mul- These live in the tree and a yellowish, then reddish, color. Once tiple stress agents (e.g. overstocked infect Sirex woodwasp larvae during wasps have completed development, stands, droughts, native pest insects their development. They do not kill adults create holes in the wood when and disease) that generally can stress the larvae, rather, they remain inside they exit the tree. These emergence pines make this region favorable for the insects and sterilize the adult. Should the Sirex woodwasp reach the holes are almost perfectly round, insect establishment should the Sirex Figure 8. Sirex woodwasp emergence holes. Figure 9. Sirex woodwasp damage in an unthinned pine plantation in Australia. The unthinned ~1/4” in diameter (Fig. 8), and tend woodwasp arrive. For this reason, southeastern U.S., natural enemies portion has nearly 70% mortality, while the thinned section has no mortality. to appear in groups of varying sizes1. preventative techniques, such as will be an important component of an Often, a single tree may have a lot of timely stand thinnings, truly are the proper silvicultural practices7,8 (Fig. 9). integrated pest management plan for emergence holes while neighboring best management. Since the Sirex Further, select tree species that are this pest. trees have few or none. Sirex wood- woodwasp primarily attacks stressed adapted to local environmental and wasp emergence holes cannot be or weakened trees, it is important soil conditions when planting, and distinguished from native woodwasp to promote stand health through manage your stand by thinning to a c e recommended levels (it is usually rec- ommended that southern pine stands a b having a basal area >120 ft2/ac be thinned to <80 ft2/ac). Stand manage- ment recommendations for the south- ern pine beetle would simultaneously reduce the hazard to Sirex woodwasp f infestation and damage (see http:// www.barkbeetles.org/standvisual/ for d

more information, or contact your lo- b cal forestry professional). Overall, tree resistance (maintained by promoting healthy pine stands) is one of the most important factors in preventing Sirex woodwasp infestations9. Natural Enemies

In its native range, a diverse group of Figure 10. Natural enemies of woodwasps in the southeastern U.S.: anceps (A), (B), peruasoria (C), Rhyssa lineo- natural enemies is believed to reg- lata (D), Megarhyssa atrata (E), Megarhyssa macrura (F). ulate Sirex woodwasp populations. The southeastern U.S. is home to a Figure 7. Resin beading (A) and running (B) on pines as a result of Sirex woodwasp oviposition. diverse community of natural enemies

www.southernforesthealth. 4 www.southernforesthealth. 5 AUTHORS: Oklahoma Cooperative Extension Service: Resources http://www.oces.okstate.edu/ Laurel J. Haavik, Lecturer, Department of Ecology and Evolutionary Biology, Clemson Cooperative Extension (South Carolina): University of Kansas http://www.clemson.edu/extension/ For the location and phone numbers of state agencies in the southeastern U.S. providing forestry assistance and David Coyle, Extension Associate, Southern Regional Extension Forestry and University of Tennessee Extension: UGA – D. B. Warnell School of Forestry and Natural Resources information, see the following websites: https://extension.tennessee.edu/ Texas A&M AgriLife Extension: http://agrilifeextension.tamu.edu/ Alabama Forestry Commission: http://www.forestry.alabama.gov/ SREF-FH-003 | www.sref.info Virginia Cooperative Extension: http://www.ext.vt.edu/ A Regional Peer Reviewed Technology Bulletin published by Arkansas Forestry Commission: http://forestry.arkansas.gov/Pages/default.aspx Southern Regional Extension Forestry, William G. Hubbard, Regional Forester, To locate a consulting forester: ASRED/CES- Southern Region. Florida Forest Service: http://www.floridaforestservice.com/ Association of Consulting Foresters: Georgia Forestry Commission: http://www.gatrees.org/ http://www.acf-foresters.org/acfweb. Southern Regional Extension Forestry (SREF) is a diverse team of trained natural resource educators, IT specialists, graphic designers, communi- cations and marketing experts, and media and content producers. SREF works closely with the Southern Land Grant University System, US Forest Kentucky Division of Forestry: Click on “Find a Forester”, then select your state in the Service, and state forestry agencies to develop content, tools and support for the forestry and natural resource community. To find out more http://forestry.ky.gov/Pages/default.aspx “People Search – Public” search page. about SREF programs please visit www.sref.info. Louisiana Department of Agriculture and Forestry: For more information on how to select a consulting ACKNOWLEDGEMENTS: http://www.ldaf.state.la.us/ forester, go to: Mississippi Forestry Commission: http://www.mfc.ms.gov/ We thank B. Slippers, D. Jenkins, K. Dodds, H. Campbell, and J. Nowak for helpful comments on earlier versions of this http://msucares.com/pubs/publications/p2718.pdf document, and B. Slippers and H. Goulet for providing high-resolution images. North Carolina Forest Service: http://www.ncforestservice.gov/ http://texashelp.tamu.edu/011-disaster-by-stage/pdfs/recovery/ER- 038-Selecting-a-Consulting-Forester.pdf Oklahoma Forestry Services: http://www.forestry.ok.gov/ References 9Haavik, L.J., K.J. Dodds, and J.D. Allison. 2015. Do native insects http://www.uaex.edu/environment-nature/forestry/FSA-5019.pdf and associated fungi limit non-native woodwasp, Sirex noctilio, South Carolina Forestry Commission: http://www.state.sc.us/forest/ survival in a newly invaded environment? PLoS ONE 10: e0138516. Additional information on the Sirex woodwasp is 1Ayres, M.P., J.M. Sullivan, T. Harrison, and M.J. Lombardero. available at: 2009. Diagnosing the presence of Sirex noctilio from examination 10Kroll, S.A., A.E. Hajek, E.E. Morris, and S.J. Long. 2013. Tennessee Division of Forestry: https://www.tn.gov/agriculture/section/forests of dead and dying pine trees. Report for USDA APHIS. www. Parasitism of Sirex noctilio by non-sterilizing Deladenus siricidicola http://southernforesthealth.net/ dartmouth.edu/~mpayres/pubs/SirexDiagnostics.pdf. 14 p. in northeastern North America. Biol. Control 67: 203-211. Texas A&M Forest Service: http://texasforestservice.tamu.edu/ http://www.woodwasps.com/

2Ayres, M.P., R. Pena, J.A. Lombardo, and M.J. Lombardero. 11Madden, J.L. 1975. An analysis of an outbreak of the woodwasp, Virginia Department of Forestry: http://www.dof.virginia.gov/ 2014. Host use patterns by the European woodwasp, Sirex Sirex noctilio F. (Hymenopter, Siricidae) in . Bull. noctilio, in its native and invaded range. PLoS ONE 9: e90321. Entomol. Res. 65: 491-500. For the location and phone numbers of University Photo Credits Extension personnel in the southeastern U.S. providing 3Coutts, M.P. 1969. The mechanism of pathogenicity of Sirex 12Maderni, J.F.P. (1998) Sirex noctilio F. present status in Uruguay. forestry assistance and information, see the following noctilio on Pinus radiata. II. Effects of S. noctilio mucus. Aust. J. Proceedings of a Conference: Training in the Control of Sirex Figure 1: Map source: USDA, and Plant Health Inspection Service, Plant Protection and Quarantine, noctilio websites: Biol. Sci. 22: 1153–1161. by Use of Natural Enemies (ed. by E. Iede, E. Shaitza, S. Science & Technology Fort Collins Lab, 2016, Penteado, R. Reardon and T. Murphy), pp. 81–82. FHTET 98-13. (ca. 1:19,000,000). Fort Collins, CO: USDA. 4 Alabama Cooperative Extension System: Coutts, M.P. and J.E. Dolezal. 1969. Emplacement of fungal USDA Forest Service, Morgantown, MV. http://www.aces.edu/main/ spores by the woodwasp, Sirex noctilio, during oviposition. For. Figure 2: Laurel J. Haavik, University of Kansas. Sci. 15: 412–416. 13Morgan, F.D. and N.C. Stewart. 1966. The biology and University of Arkansas Cooperative Extension Service: http://www.uaex.edu/ Figure 3: A and C, Steven Vallery, Oregon Dept. of Ag., behaviour of the woodwasp Sirex noctilio F. in New Zealand. Bugwood.org; B and D, Henri Goulet, Agriculture and 5Coyle, D.R. and K.J.K. Gandhi. 2012. The ecology, behavior, Trans. Royal Soc. New Zealand Zool. 7: 195-204. University of Florida’s Institute of Food and Agricultural Agri-Food Canada. and biological control potential of hymenopteran parasitoids of Sciences (UF/IFAS): woodwasps (: Siricidae) in North America. Environ. 14Ryan, K. and B. Hurley. 2012. Life history and biology of Sirex http://solutionsforyourlife.ufl.edu/ Figure 4: Henri Goulet, Agriculture and Agri-Food Canada. Entomol. 41: 731-749. noctilio. Pages 15-30 in B. Slippers, P. de Groot, and M.J. Wingfield, Figure 5: Laurel J. Haavik, University of Kansas. editors. The Sirex Woodwasp and its Fungal Symbiont: Research University of Georgia Extension: http://extension.uga.edu/ 6 Dinkins, J.E. 2011. Sirex noctilio host choice and no-choice and Management of a Worldwide Invasive Pest. Springer, New York. Kentucky Cooperative Extension Service: Figure 6: A, Bernard Slippers, Forestry and Agricultural bioassays: woodwasp preferences for southern U.S. pines. M.S. https://extension.ca.uky.edu/ Biotechnology Institute; B, Vicky Klaser, Instituto Thesis, University of Georgia, Athens. 15Spradbery, J.P. and A.A. Kirk. 1978. Aspects of the ecology of Nacional de Tecnologia Agropecuaria, Bugwood.org. Louisiana Cooperative Extension Service: siricid woodwasps (Hymenoptera: Siricidae) in , North http://www.lsuagcenter.com/ Figure 7: A, Laurel J. Haavik, University of Kansas; B: Dennis 7Dodds, K.J., R.R. Cooke, and D.W. Gilmore. 2007. Silvicultural Africa and Turkey with special reference to the biological control Haugen, Bugwood.org. options to reduce pine susceptibility to attack by a newly detected of Sirex noctilio F. in Australia. Bull. Entomol. Res. 68: 341-359. Mississippi State University Extension Service: , Sirex noctilio. North. J. Appl. For. 24: 165-167. http://extension.msstate.edu/ Figure 8: Dennis Haugen, Bugwood.org. 16Thompson, B.M., J. Bodart, C. McEwen, and D.S. Gruner. 2014. North Carolina Cooperative Extension: Figure 9: Dennis Haugen, Bugwood.org. 8Dodds, K.J., R.R. Cooke, and R.P. Hanavan. 2014. The effects of Adaptations for symbiont-mediated external digestion in Sirex https://www.ces.ncsu.edu/ silvicultural treatment on Sirex noctilio attacks and tree health in noctilio (Hymenoptera: Siricidae). Ann. Entomol. Soc. Am. 107: Figure 10: Henri Goulet, Agriculture and Agri-Food Canada. Northeastern United States. Forests 5: 2810-2824. 453-460.

www.southernforesthealth. 6 www.southernforesthealth. 7