|Crop Knowledge Master|
Xylosandrus compactus (Eichoff)
Victoria L. Tenbrink, Research Associate
Arnold H. Hara, Entomologist
Beaumont Research Center
Updated by: J.M. Diez April 2007
Recorded hosts of the black twig borer exceed 200 plant species and include:
Cattleya, Dendrobium, Epidendrum, Vanda, anthurium, avocado, citrus, coffee, cacao, brushbox (Tristania conferta), turpentine tree (Syncarpia glomulifers), paper-bark (Melaleuca leucadendron), red-ironbark eucalyptus (Eucalyptus sideroxylon), blackbutt eucalyptus (E. pilularis), robust eucalyptus (E. robusta), Koa haole (Leucaena glauca), guava, vervain (Stachytarpheta jamaicensis), Christmasberry (Schinus terebinthifolia) floral red ginger, litchi, macadamia, mango, mahogany, hibiscus, kukui, star jasmine, pikake, periwinkle, Surinam cherry. (Davis, 1963; Davis, 1969; Dixon & Woodruff, 1982; Hara & Beardsley, 1979; Mangold et al., 1977; Marsden, 1979; Nelson & Davis, 1972).
The black twig borer is native to Asia, but has spread to coffee growing areas of the world. Considered a serious coffee pest in French Guinea, it is also widely distributed the tropical areas of West Africa, coffee growing areas of East Africa, Madagascar, Mauritius, Seychelles, India, Malaysia, Java, Sumatra, and Fiji. (Davis, 1963; Nelson & Davis, 1972). In Japan it attacks tea (Hara & Beardsley, 1979). New World locations include Brazil and Cuba (Dixon & Woodruff, 1982). In the U. S. it is established in Hawaii and the Southeastern states (Mangold et al., 1977). It was discovered at Kailua, Oahu in November of 1961 and is now widespread in the Islands (Nelson & Davis, 1972). A ban on shipment of woody plants to Hawaii Island failed to prevent its introduction into the coffee growing areas of that Island (Davis, 1963).
Female black twig borers tunnel into woody twigs, leaving pin-sized entry holes. Once inside they excavate galleries and lay eggs. This excavation, along with the introduction of pathogens, is the cause of damage to the host. Damage is not caused by feeding, since the beetle larvae feed on ambrosia fungus introduced by the female. Infestation by one to three females is sufficient to kill the twig or branch. Infestation becomes apparent when die-back of twigs and branches occurs. A severe infestation can kill host plants, including large trees (Nelson & Davis, 1972; Hara & Sewake, 1990). The black-twig bore has become a serious pest of coffee in the Kona-area.
The black twig borer belongs to the tribe Xyleborini, all of which feed on ambrosia fungus and are called ambrosia beetles. The black twig borer is somewhat unique in that it attacks living plants rather than dead or dying ones. There is some evidence that stressed plants are more susceptible to infestation (Hara & Beardsley, 1979). The life cycle of the black twig borer is completed in about a month. Males spend their entire lives inside the brood gallery. Females mate inside the brood gallery and then leave to produce new galleries. Females can reproduce without mating, in which case the offspring are all males
Eggs are laid in galleries in the twigs. The tiny eggs (less than 1 mm long) are smooth, white ovals laid over a period of several weeks. They hatch three to five days after being laid (Hara & Beardsley, 1979).
Larvae are grubs, white and legless. There are two larval instars. Larvae feed on ambrosia fungus in the gallery and pupate after about 7 days (Hara & Beardsley, 1979).
The pupae are initially white, changing to light brown with black wings (female) near maturity. This process takes at least 6 days (Hara & Beardsley, 1979).
Female adults, initially light brown, turn shiny black in 3 to 4 days; females are 1.6-1.8 mm long (about 1/16 in). Males are about half as long and incapable of flight. After emerging from the pupal stage they turn from light brown to reddish brown in 3 to 4 days. (Hara & Beardsley, 1979).
Black twig borers spend the majority of their lives inside the host plant. The exception is the adult female, which leaves the gallery by way of the parentŐs entrance hole and establishes a new gallery elsewhere.
Pruning and destruction of beetle-infested plant material is essential. Good tree care to promote tree vigor and health will help in resisting infestation or recovering from infestation.
Mass-trapping of adult beetles is an option currently (2006) being investigated, using various types of traps and attractants.
Literature on natural enemies indicates the black twig borer is parasitized by at least one species of eulophid wasps of the genus Tetrastichus (Davis, 1963). Nine species of this genus, all accidentally or purposely introduced, are in Hawaii; whether any are parasitizing black twig borer is not recorded (Nishida, 1992). Three braconid wasps were imported by the Hawaii Department of Agriculture in the 1960Ős but did not become established (Heu, unpublished data).
Biological control of black twig borer is being looked into, to determine if there are any predators present in Hawaii.
Chlorpyrifos provided 83% mortality of all stages of the black twig borer infesting flowering dogwood in Florida (Mangold et al., 1977). Hata & Hara (1989) reported 100% mortality of adult females with chlorpyrifos. Marsden in 1972 recommended malathion (not to be applied to blooming orchids). Consult the University of Hawaii Cooperative Extension Service for up to date recommendations. Note that these recommendations are not for coffee.
There no listing for malathion and chlorpyrifos is not labelled as of April 2007.
Davis, C. J. 1963. Notes and Exhibitions. Proc Hawaiian Entomol Soc. 23 (2): 197.
Davis, C. J. 1969. Notes and Exhibitions. Proc Hawaiian Entomol Soc. 20 (2): 262.
Dixon, W. N. & R. E. Woodruff. 1982. The black twig borer, Xylosandrus compactus (Eichhoff) (Coleoptera: Scolytidae). Florida Dept. Agric. & Consumer Serv. Division of Plant Industry. Entomology Circular No. 250.
Hara, A. H. & J. W. Beardsley, Jr. 1979. The biology of the black twig borer, Xylosandrus (Eichhoff), in Hawaii. Pro. Hawaiian Entomol Soc. 18 (1): compactus 55-70.
Marsden, D. A. 1979. Control of the black twig borer. Hawaii Cooperative Extension Service, Farm and Home Insect Pests, Entomology Note # 5. University of Hawaii at Manoa: Honolulu.
Mangold, J. R., R. C. Wilkinson, & D. E. Short. 1977. Chlorpyrifos sprays for control of Xylosandrus compactus in flowering dogwood. J Econ. Ent. Soc. 70: 789-790.
Nelson, R. E. & C. J. Davis. 1972. Black twig borer, a tree killer in Hawaii. USDA Forest Service Research Note PSW 274. U. S. Dept of Ag.: Berkeley, CA.
Nishida, G. M., ed. 1992. Hawaiian Arthropod Checklist. Bishop Museum Press: Honolulu.
DEC/1994. Last updated 3 July 2006, MGW