DIVISION OF AGRICULTURE R E S E A R C H & E X T E N S I O N University of Arkansas System Agriculture and Natural Resources

FSA7071 Invasive Woodwasp, noctilio: APotential Pest of in Arkansas

The Sirex woodwasp, Sirex noctilio combined value of logs and bolts, John D. Hopkins Fabricius (:Siricidae), lumber, veneer and pulpwood Associate Professor and is an exotic wood­boring that production is greater than $8 billion Extension Entomologist serves as a vector for the disease per year (USDA, APHIS, 2006a). fungus, areolatum. Even­aged stands and/or stressed Tamara Walkingstick Together, this exotic wasp and pine trees are particularly at risk. Associate Professor ­ fungus can colonize a wide range of However, because North American Forestry North American pines and cause native pine ecosystems are more considerable tree mortality. diverse and complex than pine planta­ Jim Lee Wallace tions in and planted with southern North Arkansas State Plant American species, predicting the Board (Retired) Invasiveness and Pest Potential impact of S. noctilio is difficult. In South America, the insect has caused upwards of 80 percent mor ­ Silvicultural treatments aimed tality in plantations planted with at maintaining tree vigor and forest non­native North American pine health may help reduce the impact species. In the fall of 2004, S. noctilio of S. noctilio on pine forests. was trapped for the first time in the Physiological stress factors, includ ing United States in state storm damage, drought, competition (Hoebeke et al., 2005) and has sub ­ and defoliators, can predispose trees sequently been found in a number to attack by , including S. noc­ of counties in New York and Pennsyl ­ tilio. Maintain ing tree health may vania and adjacent areas in Ontario, reduce the risk to attack. However, Canada. The mode of introduction into S. noctilio females will also oviposit the United States is likely to be into healthy trees, stressing the trees through importation of infested and predisposing them to future wooden crates, pallets and other attacks (Thayer, 2007, USFS, 2006). wood packaging. S. noctilio is native to , Although not discovered in the and northern Africa, where southern states yet, this exotic insect it is generally considered to be a pest poses a potential threat to the secon dary pest. It was inadvertently southeastern forest products industry, introduced into New Zealand, especially because all southern pine Australia, , , species are vulnerable to attack. , and . In Arkansas Is Softwood production in the United these Southern Hemisphere countries, States is a multibillion dollar industry S. noctilio attacks exotic pine planta­ Our Campus that provides numerous commodities. tions, most of which are planted with In the southern states where pine North American pine species, espe­ cially Monterey pine () production typically occurs in large, Visit our web site at: s .uada even­aged, managed stands, the and loblolly pine (P. taeda). Pines are http ://www.uaex .edu

University of Arkansas, United States Department of Agriculture, and County Governments Cooperating the main hosts of S. noctilio, and body coloration. The adult female the insect can complete its life is steel­blue except for reddish­ cycle on numerous species within brown legs. Pointing backwards the pine genus (Pinus), including from the underside of the abdomen P. attenuata, P. banksiana, P. bru­ is a spike­like projection which tia, P. calabrica, P. canariensis, protects the ovipositor (egg­laying P. caribaea, P. contorta, P. densi­ tube) when not in use. The middle flora, P. echinata, P. elliotii, segments of the abdomen in the P. halepensis, P. jeffreyi, P. muri­ adult male are orange­yellow, and cata, P. nigra austriaca, P. nigra, the hind legs are thickened and P. palustris, P. patula, P. pinaster, almost wholly black. P. pinea, P. ponderosa, P. radiata, P. Larvae are creamy white, sylvestris and P. taeda (Appendix A; legless and have a distinctive dark USDA, APHIS, 2006a). In the spine at the rear of the abdomen. United States (New York), P. S. noctilio can go through its strobus (white pine) and P. resinosa life cycle in as little as 10 months (red pine) have served as hosts for but may take up to two years in S. noctilio. Also, S. noctilio has been cooler climates. Males emerge recorded on other conifers, such as before the females. Male S. noctilio larch (Larix spp.), Douglas fir engage in lekking behavior, in (Pseudotsuga menziesii), spruce which they fly in single­sex (Picea spp.) and fir (Abies spp.). swarms around the tops of trees; individual females fly into these A prediction model for the leks to mate. Females that do not potential distribution of S. noctilio mate lay eggs that produce all in found that many males, whereas mated females areas of the United States, Canada produce offspring of both sexes. and Mexico were suitable for Females can begin to lay eggs establishment (Carnegie et al., one day after adult emergence. 2006). S. noctilio can tolerate the Adults do not feed; instead, they climates found within the United live on fat stored in their bodies. States, and thus, APHIS expects The adult life span can last up to that the absence of suitable host 12 days, but females that deposit pines will probably be the factor all their eggs may survive for an most limiting the distribution of S. additional three to four days. noctilio. S. noctilio can likely Throughout their short life, establish wherever pines are found females deposit between 20 and in North America. 500 eggs, depending on the size of the female (larger females Native species of siricid generally lay more eggs). woodwasps are present in many ecosystems in North America, but In preparation for egg these native woodwasps differ deposition, females land on trees, from S. noctilio in that this non­ drill into the wood and assess the native species will attack appar­ suitability of the tree for oviposit­ ently healthy trees, whereas native ing. If the tree is unacceptable for siricids only attack trees that have oviposition, the female will fly to been weakened (USFS, 2005). another tree. If the tree is accept­ able, she lays a single egg and then continues to move upward in Description and Biology a spiral pattern, drilling up to four more holes and depositing the of Sirex noctilio remainder of her eggs. Females, The Sirex woodwasp is a after ovipositing in one tree, may relatively large insect, ranging move on to additional trees as long from 1.0 to 1.5 inches long, with as their eggs and energy reserves metallic (iridescent) blue­black hold out. Mucus that is toxic to pine trees is injected during Larvae hatch from the eggs exit hole, which varies in diameter drilling. The mucus causes the after a minimum of 9 days; according to the size of the wasp. foliage to wilt and yellow, creating however, the eggs may remain ideal conditions for the spread of dormant for several months, over­ At low population levels, fungus. The last hole is packed with wintering in cooler climates. The S. noctilio selects stressed and spores of a fungus (Amylostereum number of larval instars varies injured trees for egg laying; how­ areolatum). The fungus causes the from 6 to 12, and the larval stage ever, at high population densities, S. noctilio will select healthy trees. wood to dry out, thereby creating generally takes 10 to 11 months. Foliage of infested trees initially a more favorable environment for Larval tunnels created in the wood wilts and then may change color egg hatching. After hatching, the are tightly packed with very fine S. noctilio larvae feed on this from dark green to light green to sawdust. Mature larvae pupate fungus. These effects together yellow and finally to red during close to the surface. The pupal may kill the tree. the three to six months following stage lasts between 16 and 21 days. attack. In the northeastern When a female wasp emerges from United States, some trees struck her pupal skin, she takes up fungal by S. noctilio have wilted and the spores from the tree from which needles have turned brown with­ she emerges and stores them in a out the gradual color change. special organ in her abdomen. The Infested trees may have resin adult wasp bores its way out of the beads or dribbles at the egg­laying tree, leaving a characteristic round sites, but uninfested trees may also exhibit resin beads and dribbles as well.

Contact the Arkansas State Plant Board (501­225­1598) or your local county Extension office for more information.

Photo credits: Dennis A. Haugen, USDA Forest Service, Forest Health Protection, St. Paul, MN.

References Carnegie, A.J., M. Matsuki, D.A. Haugen, B.P. Hurley, R. Ahumada, P. Klasmer, J. Sun and E.T. Iede. 2006. Predicting the potential distribution of Sirex noctilio (Hymenoptera:Siricidae), a significant exotic pest of Pinus plantations. Annals of Forestry Science. 63:119­128.

Hoebeke, E.R., D.A. Haugen and R.A. Haack. 2005. Sirex noctilio: Discovery of a Palearctic siricid woodwasp in New York. Newsletter of the Entomological Society 50(1&2):24­25. Thayer, Charles L. 2007. United States Associated with U.S. Forest Service, Northeastern (Fr.) the Woodwasp, Sirex noctilio Area State and Private Boidin Sirex­Fungus: Pest Fact Fabricius, and the Symbiotic Forestry. 2005. Pest Alert, Sirex Sheet. U.S. Department of Fungus, Amylostereum areola­ woodwasp – Sirex noctilio F. Agriculture, and Plant tum (Fries:Fries) Boidin. July, (Hymenoptera: Siricidae). Health Inspection Service. 2006. Raleigh, NC. NA–PR–07–05, June, 2005. http://www.aphis.usda.gov/plant USDA, APHIS, 2007. Proposed U.S. Forest Service. 2006. Southern _health/plant_pest_info/sirex/ Program for Management of Forest Health and Research downloads/sirexfungus.pdf. the Woodwasp Sirex noctilio Update, Sirex noctilio in North Accessed date 11/20/2007. Fabricius (Hymenoptera: America. Summer 2006, Vol. 1, U.S. Department of Agriculture, Siricidae). Environmental Issue 1: http://www.fs.fed.us/ Animal and Plant Health assessment. http://www.aphis. r8/foresthealth/publications/ Inspection Service. 2006a. usda.gov/plant_health/ea/ southern_fhp_research_update/ Organism Pest Risk Analysis: downloads/sirex­ea.pdf. summer2006_vol1_1.pdf. Risks to the Conterminous Accessed date 11/06/2007. Accessed Date 11/20/2007.

DIVISION OF AGRICULTURE R E S E A R C H & E X T E N S I O N University of Arkansas System

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DR. JOHN D. HOPKINS is Associate Professor and Extension Issued in furtherance of Cooperative Extension work, Acts of May 8 and Entomologist with the University of Arkansas Division of Agriculture, June 30, 1914, in cooperation with the U.S. Department of Agriculture, Little Rock. DR. TAMARA WALKINGSTICK is Associate Professor ­ Director, Cooperative Extension Service, University of Arkansas. The Forestry and Associate Director ­ Arkansas Forest Resources Center with Arkansas Cooperative Extension Service offers its programs to all eligible the University of Arkansas Division of Agriculture, Little Rock. JIM LEE persons regardless of race, color, national origin, religion, gender, age, dis­ WALLACE is former State Survey Coordinator with the Arkansas State ability, marital or veteran status, or any other legally protected status, Plant Board, Little Rock (retired). FSA7071­PD­4­2014RV and is an Affirmative Action/Equal Opportunity Employer.