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Plantwise Technical Factsheet

Formosan subterranean termite (Coptotermes formosanus)

Host plants / species affected
Acer rubrum (red maple)
Chamaecyparis thyoides (Atlantic white cedar)
Cinnamomum camphora (camphor laurel)
Citrus
Eucalyptus
Fraxinus berlandieriana
Liquidambar styraciflua (Sweet gum)
Picea engelmannii (Engelmann spruce)
Pinus (pines)
Quercus (oaks)
Saccharum officinarum (sugarcane)
Taxodium distichum (bald cypress)
List of symptoms/signs
Fruit  -  internal feeding
Roots  -  external feeding
Roots  -  internal feeding
Stems  -  internal feeding
Stems  -  wilt
Whole plant  -  internal feeding
Whole plant  -  plant dead; dieback
Whole plant  -  wilt
Symptoms

Large colonies of C. formosanus generally live underground. When these termites invade a house aboveground, the foraging tubes of approximately 0.5-1 cm in diameter may be found connecting the soil and the infested house. In severe infestations, C. formosanus hollows out the wood leaving a paper-thin surface and the hollowed wood surface may look blistered or peeled. Another characteristic of C. formosanus is carton nest material that is made from termite faeces, chewed wood and soil. The honeycomb-like carton nests can be as large as 1-1.5 m in diameter and are usually found in structure-voids such as between walls and beneath sinks.

Prevention and control

Phytosanitary Measures

Some quarantine regulations exist that prohibit the transportation of materials infested with termites, but the quarantine is virtually unenforceable.  There are no phytosanitary measures to prevent C. formosanus being moved with potted plants, as exists for red imported fire ants (Solenopsis invicta), despite the fact that they do infest potted plants and can easily be moved to new locations.

Cultural Control and Sanitary Methods

The combination of water and wood or other cellulose materials provides attractive conditions for C. formosanus. Leaky roofs, plumbing, irrigations, air conditioning condensate and any portion of the building that may collect excessive moisture should be corrected to maintain an environment less attractive to C. formosanus. Because C. formosanus invades a house through the soil, the use of untreated wood in contact with the soil should be avoided. Plants should not be allowed to grow up onto the house structure and mulches should not be placed up against a house where the foundation becomes hidden. Wood debris should be removed and fire wood should not be stacked against the house.

Biological Control

Laboratory studies consistently demonstrated the pathogenicity of biological agents such as the entomopathogenic nematode, Neoaplectana carpocapsae [Steinernema carpocapsae] (Fujii, 1975) or the fungi Metarhizium anisopliae and Beauveria bassiana (Lai et al., 1982). However, field trials using these biological agents have been generally unsuccessful (Lai, 1977; Mauldin and Beal, 1989). Jayasimha and Henderson (2007) found that C. formosanus carries fungi on its integument and in its gut that will kill brown rot fungi (Monilinia laxa and Monilinia fructigena). Aspergillus flavus also associated with C. formosanus has potential as a biocontrol agent. Bacteria that attack Bacillus thuringiensus are also carried on the bodies of C. formosanus, and as colony size increases the ability to attack biological control agents becomes more efficient (Wang and Henderson, 2013). Most recently, bacteria has been combined with clay (an attractant and spore stabilizer) and low concentrations of a chitin synthesis inhibitor to successfully control C. formosanus in the lab. Field trials are still needed.

Chemical Control

Chemicals used for the control of C. formosanus can be grouped into three categories: wood preservatives, liquid insecticides for soil barrier treatments and bait toxicant for population control.

Wood that is pressure-treated with preservatives (creosote and inorganic salts such as chromated copper arsenate) were required by building codes in many states for use at the point of wood-soil interface. Arsenic and creosote now have very few uses, and various formulations using copper and borates dominate the market place today. These preservatives are primarily used to prevent fungal decay, but they also prevent termite damage to the wood.

The most frequently used control measure against C. formosanus is to place a chemical barrier between the termites and the structure to be protected. Cyclodienes such as chlordane have been in widespread use but are now banned. The organophosphate chlorpyrifos, which replaced cyclodienes in the mid-1980s, was recently phased out due to human toxicity concerns. Termiticides that are currently available include permethrin, cypermethrin, bifenthrin, fenvalerate, imidachloprid, fipronil, chlortraniliprole and chlorfenapyr, which are labelled under various trade names. Pyrethroids such as permethrin, cypermethrin, bifenthrin and fenvalerate repel the termites from treatment barriers, whereas other termiticides prevent termite invasion by lethal contact. Newer termiticides (such as fipronil, imidacloprid, chlortraniliprole) are non-repellents and are transfered from termite to termite via grooming and nestmate contacts, resulting in colony collapse.

For pre-construction treatments, soil termiticides are applied onto sub-slab soil before the foundation is poured. Post-construction treatments can be carried out by drilling holes through the slabs, injecting insecticides under the foundations and by drenching the trenches dug into the soil along the building foundations.

Unlike repellent soil termiticide treatments, baits are intended to control C. formosanus populations near a structure. One such approach is the monitoring-baiting programme that incorporated a bait matrix containing the chitin synthesis inhibitor, hexaflumuron (Su, 1994). Stations containing a monitoring device are first installed in the soil surrounding a home. When the termites are found in the station, the monitoring device is replaced with a tube containing the hexaflumuron-laced bait (Su et al., 1995). The termites feeding in the stations then carry the baits to other members of the colony, leading to the demise of the entire colony population. Field trials using hexaflumuron baits repeatedly demonstrated that baited C. formosanus colonies could be eliminated from a location (Su, 2003b). When hexaflumuron went off patent (ca. 2010) this chitin synthesis inhibitor was incorporated into bait stations sold directly to homeowners at home improvement stores. Some other bait stations use noviflumuron. Although baits can be an excellent choice and are environmentally friendly, bait stations can be bypassed by foraging termites. Slow-acting and non-repellent chemicals in bait stations are needed to cause an impact on C. formosanus populations. Other chemicals that are used for termite baits include chitin synthesis inhibitors such as diflubenzuron, noviluron and lufenuron. Metabolic inhibitors such as sulfluramid and hydramethylnon are no longer being used in termite baits.

Field Monitoring

Electronic sensors are available for automated monitoring (Su, 2002), and a pop-up mechanism is used in over-the-counter bait stations to indicate possible termite presence. Although the bait label may require only yearly checks, most professionals will check stations more frequently to ensure enough bait is in place at all times.

IPM Programmes

The baiting programme employs a cyclical procedure to protect a house from invading C. formosanus in the soil. Non-toxic monitors are no longer often used before employing baits. Most baits used today incorporate the toxicant at the start of a baiting programme. After eliminating C. formosanus populations near the house, monitoring resumes using the same toxic baits. The baiting procedure forms the basis for an on-going programme to protect structures from C. formosanus infestations (Su and Scheffrahn, 1998b).

Related treatment support
 
External factsheets
USDA-NAL National Invasive Species Information Center Species Profiles, USDA-NAL National Invasive Species Information Center (NISIC), 2012, English language
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