Invasive : Risks and Pathways Project BLACK TWIG BORER

UPDATED: APRIL 2020

Invasive insects are a huge biosecurity challenge. We profile some of the most harmful invaders overseas to show why we must keep them out of .

Species Black twig borer / compactus. Also known as black borer, black coffee twig borer, tea stem borer. Main impacts Kills stems of and and sometimes whole , including endangered . Damages food crops and ornamental plants. Native range East .1 Invasive range South East Asia, Pacific islands, USA, Caribbean Islands, Brazil, Peru, (27 countries).1 Black twig borers in their gallery, which they inoculate with symbiotic fungi that serve as Main pathways of global spread food for adults and larvae. Trade of infested plants, foliage, wood Photo: Raffaele Giurato 1 and packing wood material. 3 attack . The also killed swamp mahogany (E. robustus) during droughts3, ENVIRONMENTAL and has attacked many other Australian IMPACTS OVERSEAS trees grown in Hawaii4. In it increases the susceptibility to stem The black twig borer bores into the stems breakage and death of koa (Acacia of shrubs and trees of more than 200 melanoxylon), a Hawaiian wattle closely species, often killing shrubs and related to Australian blackwood (A. sometimes large trees. Fungi associated melanoxylon)5. with the beetle that are important for development of their larvae contribute to In Hawaii the beetle is a threat to the damage2. endangered plants, including Hawaii plum ( macrococcus), which This beetle was called ‘a threat to natural has a population of no more than 3000 ecosystems in Europe’ after infestations individuals, usually ‘partially dead as in Circeo National Park in Italy caused 6 serious declines, with wilting of oaks, bay a result of heavy infestation’ , and the trees, mastics, carobs and other trees, and critically endangered hame ( neowawraea 7 the death of young plants 2. This came ) . only five years after the beetle was first detected in Europe in 2011 2. HUMAN AND ECONOMIC IMPACTS In Hawaii the have killed An adult black twig borer. Photo courtesy Australian trees grown in plantations, OVERSEAS Michael C. Thomas, Florida Department notably eucalypts (Eucalyptus pillularis, This beetle attacks many crops including of Agriculture and Consumer Services, E. sideroxylon), brush box (Lophostemon Bugwood.org | CC BY-SA 3.0 mangoes, macadamias, avocadoes, figs, confertus), paperbark (Melaleuca coffee and lychees, and many ornamental leucadendron) and turpentine (Syncarpia 3 plants, including hibiscuses and coral glomulifera) . All of the killed trees had trees1 apparently been vigorous before the .

INVASION WATCH: Black twig borer AUSTRALIAN endangered, and 22 endangered 6. NatureServe (2009): CONCERNS eucalypts, plus large numbers of - Radlk. An Online Encyclopedia of Life. vulnerable species, although some occur Retrieved from http://explorer.natureserve.org/ This black twig borer could threaten a in regions unsuitable for the black twig servlet/NatureServe?searchName=Alectryon+ macrococcus. wide range of Australian plants. Its global borer. distribution suggests it could invade 7. World Conservation Monitoring Centre northern, eastern and south-western So broad are the borer’s tastes that rare (1998): . The IUCN Red Australia. species in many other Australian genera List of Threatened Species. International Union are likely to be susceptible. Vulnerability for the Conservation of Nature. Retrieved from As noted above, it kills Australian plants to the borer varies between species, so http://dx.doi.org/10.2305/IUCN.UK.1998.RLTS. grown abroad, including eucalypts, brush it is impossible to predict which species T33605A9795540.en. box, paperbarks and turpentine. Other are at serious risk, but the large number 8. Intachat J, Kirton LG (1997): Observations Australian plants attacked in Hawaii of threatened Australian plants and the on insects associated with Acacia mangium in include blackwood (Acacia melanoxylon), wide tastes of the borer suggest that Peninsular Malaysia. Journal of Tropical Forest Science candlenut (Aleurites moluccana), Norfolk some could face extinction if it arrives. . 9: 561–564. Island pine (Araucaria heterophylla), 9. Hara AH, Beardsley JW (1976): The beautyberry (Callicarpa pendunculata), Plant Health Australia has identified the biology of the black twig borer, Xylosandrus beach she-oak (Casuarina equisetifolia), black twig borer as a high priority pest compactus (Eichhoff), in Hawaii.Proceedings of 12 the Hawaiian Entomological Society red ironbark (Eucalyptus sideroxylon), of mangoes and a pest of macadamia . 23: 55–70. trees13 maple (Flindersia brayleyana), . 10. Department of Environment and Science coast hibiscus (Hibiscus tiliaceus), Tahitian (n.d.): Alectryon repandodentatus, WetlandInfo. chestnut (Inocarpus fagifer), macadamia SOURCES Queensland Government. Retrieved from (Macadamia integrifolia) and red cedar https://wetlandinfo.des.qld.gov.au/wetlands/ 1. European and Mediterranean Plant ecology/components/species/?alectryon- (Toona ciliata)4. In Malaysia it damages Protection Organization (2017): EPPO Alert repandodentatus. seedlings of mangium (Acacia mangium), List – (Coleoptera: 11. Department of the Environment and Energy an Australian wattle grown there in Scolytidae) and its associated fungi. Retrieved 8 (n.d.): Species Profile and Threats Database. plantations . from https://www.eppo.int/ACTIVITIES/ EPBC Act list of threatened flora. Australian plant_quarantine/alert_list_insects/xylosandrus_ Australia has many other native plants Government. Retrieved from http://www. compactus. in genera that are attacked overseas, environment.gov.au/cgi-bin/sprat/public/ Abutilon Acalypha Alectryon 2. Vannini A, Contarini M, Faccoli M, Dalla Valle publicthreatenedlist.pl?wanted=flora. including , , , et al Alpinia Antidesma Bauhinia, Canavalia M, Rodriguez CM, Mazzetto T, . (2017): 12. Plant Health Australia (n.d.): Black , , , First report of the Xylosandrus Citrus Claoxylon Colubrina Croton twig borer. Retrieved from http://www. , , , , compactus and associated fungi in the Cryptocarya, Dendrobium, Diospyros, planthealthaustralia.com.au/pests/black-twig- Mediterranean maquis in Italy, and new host- borer/. , Ficus, Flueggea, Graptophyllum, pest associations. Bulletin OEPP. 47: 100–103. 13. Plant Health Australia (n.d.): Macadamias. Hibiscus, Jasminum, Metrosideros and Black twig borer, 3. Nelson RE, Davis CJ (1972): Retrieved from http://www.planthealthaustralia. Pipturus, Pittosporum, Rubus, Santalum, a killer in Hawaii . USDA Forest Service com.au/industries/macadamias/. Solanum, Syzygium and Vitex4,9. Research Note PSW 274, US Department of Agriculture. Australia has threatened species in ABOUT THIS PROJECT several of the genera attacked overseas, 4. Hara AH, Beardsley JW (1976): The biology of the black twig borer, Xylosandrus compactus including the critically endangered Phillip The Invasive Insects: Risks and (Eichhoff), in Hawaii.Proceedings of the Island hibiscus (Hibiscus insularis) and Pathways Project is a partnership Hawaiian Entomological Society. 23: 55–70. between Monash University and the Invasive two relatives of the endangered Hawaii Species Council. To find out more visit Alectryon repandodentatus 5. Ishihara KL, Corpuz M, Morden CW, plum – , invasives.org.au/risks-and-pathways. 10 Borthakur D (2017): , ecology and endangered in Queensland , and the Acacia koa 11 diversity of in the Hawaiian Islands. federally endangered A. ramiflorus . American Journal of Agricultural and Biological Australia has 30 acacia species listed Sciences. 12: 66–78. federally as endangered or critically

INVASION WATCH: Black twig borer