Senior Seminar 2002
Introduced Species in Hawaii

earlham college

Termites

Coptotermes formosanus
Common Name: Formosan subterranean termite


C. formosanus soldier
Photo courtesy of: Agricultural Reasearch Service

Introduction
Of the eight species of introduced termites, Coptotermes formosanus has created the greatest economic damage and is the cause of greatest concern for the Hawaiian Islands (Grace et al. 2002). C. formosanus and the other termites came to the islands on boats following World War II. The University of Hawaii continues to be a center of research into the biology, behavior, and control of this pest. The future looks promising as old methods of management are refined, and new methods are developed.


C. formosanus queen   
Photo courtesy of: Agricultural Research Service

Description
Coptotermes formosanus is a generalist, colonial, social insect building colonies either above or below ground (Howarth 1985). Termites have a caste system including: a king, queen, workers, soldiers, and reproductives or alates (winged termites). The workers provide the food, soldiers defend the nest, and reproductives breed the colony. The colony is led by a queen who has a life span of approximately 15 years and is capable of producing up to 2,000 eggs a day. The workers and soldiers may live 3-5 years with caste proportions of approximately 360 workers: 40 soldiers (Grace et al. 1996a). A colony is surrounded by an extensive foraging system consisting of tunnels underneath the ground, with a mature colony containing millions of termites (Tulane 2002, ARS 2002). Grace et al. (1995) found older and less vigorous colonies contained workers who had a larger body mass than workers in younger colonies. The diet of the subterranean termite consists of anything that contains wood fiber (homes, building, live trees), crops, and plants. Live trees include: Oak, Ash, and water-bound Cypress (ARS 2002). Crops include sugarcane (Broughton and Grace 1994).

        
            C. formosanus cartonous nest
       Photo courtesy of:  Agricultural Research Service

In addition to C. formosanus, there are seven other species of introduced termites to the Hawaiian Archipelago:

Coptotermes vastator

Common Name: Philippine milk termite
Limited distribution in Hawaii. Most serious pest in Guam and the Philippines. Interactions with C. formosanus may limit its distribution in Hawaii (Grace et al. 2002).

Cyptotermes cynocephalus
Common Name: Indo-Malaysian termite
Collected on Oahu, although only in a very limited area. Found among dead vegetation rather than structural timbers (Grace et al. 2002).

Cryptotermes brevis
Common Name: West Indian drywood termite
Long-term resident of Hawaii. Commonly found in buildings (Grace et al. 2002).

Incisitermes immigrans
Common Name: Lowland tree termite
Long-term resident of Hawaii. Occasionally infests structural lumber (Grace et al. 2002).


Neotermes connexus
Common Name: Forest tree termite
Long-term resident of Hawaii (Grace et al. 2002).

Incisitermes minor
Common Name: Western drywood termite
Most important dry wood termite pest in California. Found infesting two buildings in different parts of Oahu (Grace et al. 2002).

Zootermopsis angusticollis
Common Name: Pacific dampwood termite
Well established at high elevation on Maui. Found in California and Oregon. Usually occurs in logs and other dead wood matter on the ground. Only attacks structural wood when the wood is wet or decayed (Grace et al. 2002).


Distribution
C. formosanus is native to China and the South Pacific. In the U.S., C. formosanus has been found in Alabama, California, Florida, Georgia, Hawaii, Louisiana, Mississippi, North Carolina, South Carolina, Tennessee, and Texas (ARS 2002). It is found on all the major islands of Hawaii (Grace et al. 2002).


United States Distribution Map for C. formosanus
Photo courtesy of: Agricultural Research Service

Vectors
After World War II, military ships returning to Hawaii and the continental states from the Pacific transported the termite to the islands (Tulane 2002). Wooden boats, shipping containers, and wooden products were ideal habitats for the termite on its way Hawaii (Broughton and Grace 1994).

Broughton and Grace (1994) found low genetic variation in the C. formosanus populations of the Hawaiian Islands. They believe the current populations have all come from the same Chinese source population. A bottleneck effect may have occurred where the introduction of C. formosanus represents only a single genetic lineage, such as an invasion by a single colony.

Why C. formosanus is successful
C. formosanus is able to tunnel below soil treated with chemicals, bypassing human efforts to control termites. They are also able to tunnel through asphalt, plaster, and synthetic materials such as plastic. They have fairly minimal needs, a small amount of water and food can support a large colony (Tulane 2002).

C. formosanus thrives on Douglas-fir wood, a lumber product which is widely used in Hawaii and is resistant to chemical preservatives (Grace and Yamamoto 1994).

Impacts
C. formosanus is the most economically serious pest in Hawaii, costing residents $100 million a year (Tulane 2002). Historic structures in Hawaii have been threatened, such as Iolani Palace in Honolulu (Grace et al. 2002).

Damage to the southern United States by C. formosanus has cost $1 billion a year. In New Orleans, 30-50% of the city's 4,000 historic live Oak trees are believed to be infected with total damage costing the city $300 million a year (Tulane 2002).


Impacts of increased use of pesticides to control the termite population has lead to higher costs for homeowners and destructive effects on the environment, including contamination of water supplies caused by runoff (Yates et al. 2000).

        
Live trees are attacked as well as century old structural timbers
Photo courtesy of: Agricultural Research Service 

Management
The majority of efforts to control termites in the Hawaiian Islands are aimed at C. formosanus. Various methods are used to prevent and control this termite: physical barriers, preservative treated wood, naturally resistant woods, soil insecticide applications, and baiting systems (Grace et al. 2002).

Physical Barriers:
Particle barriers are a common form of physical barrier to termite penetration and can be made of a variety of substances: crushed basalt, silica sand, natural sand, granite, glass shards, limestone, quartz and coral sand, concrete, or brick (Yates et al. 2000).
The Basaltic Termite Barrier (BTB) was invented in Hawaii and is a non-chemical, physical barrier used to prevent termite tunneling. This screened particle barrier consists of crushed basaltic rock, screened to particle size such that termites are unable to penetrate. The termites are unable to move the particles with their mandibles, the tiny rocks are too hard for the them to crush, and it packs together too tightly for the termites to find a way through. BTB is used in all State Government construction in Hawaii and by architects in residential construction (Grace et al. 2002).

TermiMesh was invented in Australia and is a stainless steel screen commonly used in new construction to prevent termite penetration (Grace et al. 2002). Grace et al. (1996c) found TermiMesh to be an excellent preventative measure so long as it is properly installed ensuring there are no cracks between the product and unit of attachment. Cracks would enable the termites to invade and destroy the structure.

Preservative-treated wood:

Preservatives applied to wood may prevent termite attacks. Hawaii is unique among the United States in that it is the only state requiring all structural lumber used in new building construction to be pressure treated with a wood preservative. Chromated copper arsenate (CCA) and disodium octaborate tetrahydrate (DOT) are the most widely used preservatives for wood in Hawaii (Grace et al. 2002). Borate is of lower environmental impact when compared to other preservatives. An additional benefit of borate is it's fire-resistant properties. However, borate does not work well with solid wood, it only can be used with oriented strandboard. Sean et al. (1999) found 1% zinc borate to provide good protection against termite attack.

Insecticide:

This is applied to the soil to prevent a termite attack. Chlordane, once a popular insecticide, has not been used since 1986 in Hawaii due to human health and safety dangers (Tulane 2002). As a consequence, less toxic chemicals have been used as replacements such as: imidacloprid and fipronil (Grace et al. 2002). These newere chemicals have reduced longevity and consequently are applied more heavily than their more toxic counterparts (Tamashiro et al. 1990, in Yates et al. 2000). 20 years of field research at the University of Hawaii has shown pyrethroid insecticide permethrin to be long-lasting under tropical conditions. Grace et al. (1995) found termites to differ widely, under laboratory conditions, in their susceptibility to insecticides.

Naturally resistant woods:

Hawaii has recently seen a decrease in the use of plantations for growing food crops such as sugar and pineapple. Consequently there is an interest in using the land for forestry. There would be many benefits to growing termite resistant tree species that could be used as lumber for construction. Grace et al. (1996a) studied termite resistance among different species of Hawaiian-grown trees. The species with the greatest potential for termite resistance were: Cryptomeria japonica (Sugi, Taxodiaceae), Eucalyptus microcorys (Tallowwood, Myrtaceae), and Thespesia populnea (Milo, Malvaceae). The benefits of using naturally resistant woods are they are more environmentally-friendly and less toxic, than preservative treated wood. Locally grown trees would relieve the need for importation of both wood and chemicals. In addition, naturally durable wood has a higher market value than less durable wood (Grace et al. 1996a).

Baits:

In-ground and above-ground bait stations are used as a post-introduction termite control method and are ineffective when used as a preventative measure (Yates and Grace 2000). Hexaflumuron, a toxin to termites, was first used commercially in Hawaii and Florida for C. formosanus control. Baits have proven effective in Hawaii and are used to protect historic structures. They are an appealing method of termite control because this cryptic social species is able to be eliminated by a single application of a small amount of insecticide. Those termites who come in contact with the insecticide transmit it to other members of the population (Grace et al. 1996b).

          
Placement of a monitoring/baiting station              Termite bait trap in New Orleans sidewalk
Courtesy of: Agricultural Research Service


What to do if you have termite problems:
Eliminate water sources at home by:
not allowing wood to have contact with wet soil, replacing wood structures that are water-damaged, fixing leaky plumbing, fixing cracks in walls, concrete, and roof.
If you live in an area that is prone is infestation, you should have your home frequently monitored for signs of infestation by a qualified pest control operator (Tulane 2002).

The Future
The University of Hawaii continues research efforts, examining the molecular genetics of C. formosanus colonies. This will enable us to better understand how termites spread and distribute themselves, how different colonies interact, and the dynamics of social organization within a colony. This research will also help scientists in distinguishing between the various species of termites so as to better determine the efficacy of bait stations. Also of interest is greater understanding and manipulation of termite biology and behavior in order to develop more effective and environmentally sound termite control methods.

Links
The Quest for Environmentally Friendly Termite Control
The University of Georgia College of Agricultural and Environmental Sciences.
Excellent web site devoted to environmentally safe methods for termite control. Has lots of links to other sites containing general information, pest control information, and research by universities.
http://www.uga.edu/caes/insectlab/termlinks.html

National Formosan Subterranean Termite Program
US Department of Agriculture's Agricultural Research Service (ARS)
They are joining together with other governmental agencies, private organizations and universities to develop tools and strategies for dealing with termites. Their goal is to suppress termites with minimum cost and pesticide use. Plans include evaluating existing technologies and developing new ones.
http://www.ars.usda.gov/is/fullstop/

University of Hawaii Termite Project
Highlights of the site include: current research topics, lots of links, and a free newsletter entitled the Termite Times.
http://www2.hawaii.edu/~entomol/

Bibliography
Agricultural Research Service (ARS). April 2002. Agricultural Research Service Formosan Subterranean Termite Frequently Asked Questions. URL http://www.ars.usda.gov/is/fullstop/faqhome.htm (10 Oct 2002).

Agricultural Research Service (ARS). April 2002. Agricultural Research Service Formosan Subterranean Termite Program Information. URL http://www.ars.usda.gov/is/fullstop/backgrounder.htm (10 Oct 2002).

Broughton, R. E., and J. K. Grace. 1994. Lack of mitochondria-DNA in an introduced population of the formosan subterranean termite (Isoptera: Rhinotermitidae). Sociobiology 24: 121-126.

Grace, J. K., D. M. Ewart, and C. H. M. Tome. 1996a. Termite resistance of wood species grown in Hawaii. Forest Products Journal 46: 57-60.

Grace, J. K., R. J. Woodrow, and J. R. Yates. 2002.  Distribution and management of termites in Hawaii.  Sociobiology 40:  87-93.

Grace, J. K., C. H. M. Tome, T. G. Shelton et al. 1996b. Baiting studies and considerations with Coptotermes formosanus (Isoptera: Rhinotermitidae) in Hawaii. Sociobiology 28: 511-520.

Grace, J. K., and R. T. Yamamoto. 1994. Simulation of remedial berate treatments intended to reduce attack on douglas-fir lumber by the formosan subterranean termite (Isoptera: Rhinotermitidae). Journal of Economical Entomology 87: 1547-1554.

Grace, J. K., R. T. Yamamoto, and M. Tamashiro. 1995. Relationship of individual worker mass and population decline in a formosan subterranean termite colony (Isoptera, Rhinotermitidae). Environmental Entomology 24: 1258-1262.

Grace, J. K., J. R. Yates, C. H. M. Tome, et al. 1996c. Termite-resistant construction: use of stainless steel mesh to exclude Coptotermes formosanus (Isoptera: Rhinotermitidae). Sociobiology 28: 365-372.

Howarth, F. G. 1985. Impacts of Alien Land Arthropods and Mollusks on Native Plants and Animals in Hawai'i. Pp. 149-179. In, Stone, C. P. and J. M. Scott. Hawaii's Terrestrial Ecosystems Preservation and Management.

Sean, T., G. Brunette, and F. Cote. 1999. Protection of oriented strandboard with borate. Forest Products Journal 49: 47-51.

Tamashiro, M., J. R. Yates, R. T. Yamamoto, and R. H. Ebesu. 1990. The integrated management of the formosan subterranean termite in Hawaii. Pp. 77-84 in: Pest control into the 90s: problems and challenges. Applied Science Dept., City Polytechnic of Hong Kong.

Tulane University. Formosan Subterranean Termite. URL http://www.tulane.edu/~mrbc/2001/MRB%20Project/termite.htm (10 Oct 2002).

Yates, J. R., and J. K. Grace. 2000. Effective use of above-ground hexaflumuron bait stations for formosan subterranean termite control (Isoptera: Rhinotermitidae). Sociobiology 35: 333-356.

Yates, J.R., J. K. Grace, and J. N. Reinhardt. 2000. Installation guidelines for the basaltic termite barrier: a particle barrier to formosan subterranean termites (Isoptera: Rhinotermitidae). Sociobiology 35: 1-16.

 

Designed by: Shannon Marie Murphy                                     Contact: murphsh@earlham.edu
Last revised: 5 December 2002

Earlham College         Biology Department        Senior Seminar 2002