Forest and Timber Insects in New Zealand No. 62 Australian Subterranean Termites in New Zealand Insect: Coptotermes acinaciformis (Froggatt) (Isoptera: Rhinotermitidae) Coptotermes frenchi Hill Based on G.R. Sandlant (1985) Fig.1 - Subterranean termite nest in below ground portion of hardwood power pole. This pole originally imported from Australia, was in use for about 30 years before the nest was discovered. Diameter of pole 230 mm Type of injury In New Zealand, nests of Coptotermes acinaciformis and C. frenchi have been found only underground and have always been directly associated with timber imported from Australia (Fig.1). Logs in contact with the ground, stumps, dead standing or fallen trees, and untreated poles, posts, and construction timbers that are near to nests may all be attacked and destroyed by foraging workers tunnelling underground. Workers may also form earthen runways across concrete foundations to provide access to the timber in buildings (Fig.2). Living trees may be invaded via the roots. The interior of timber attacked by subterranean termites is reduced to a series of galleries, with paper thin, longitudinal partitions of wood (usually the latewood bands) between them (Fig.3). Sometimes this partitioning is entirely consumed and the large gallery so formed contains a framework of regurgitated material called honeycomb. Damage can be very extensive and remain undetected for many years. The presence of mud which subterranean termites carry to their galleries and the absence of faecal pellets distinguish the workings of these termites from those of drywood termites (Leaflet No.59). Ent_62_Coptptermes_spp.doc Page 1 Hosts Australian subterranean termites will destroy dead wood of a wide range of hardwoods and softwoods. No building timber in New Zealand is known to be resistant to damage. Attack on living trees in New Zealand has occurred in Leptospermum (manuka and kanuka), Chamaecyparis lawsoniana (Lawson cypress), Cupressus macrocarpa (macrocarpa), Juqlans (walnut), Populus (poplar), Salix (willow) and Prunus, but all of these were invaded by workers from a colony which had its nest in nearby Australian hardwood timber. No nests have been found in New Zealand-grown trees. Fig.2 - Runways made by subterranean termite workers over the concrete foundations and floor joists of a building. Fig 3- Australian hardwood timber (100 x 75 mm) eaten by subterranean termites, and showing remaining wood partitions. In Australia many species of living trees and shrubs are attacked by these termites. The nests themselves can even be present in living trees. Those of C acinaciformis are known to occur in 25 species of Eucalyptus (eucalypts) as well as in Agathis palmerstoni (northern kauri pine), Araucaria cunninghamii (hoop pine), Callitris (cypress pine), Casuarina (sheoke), and Grevillea robusta (silky oak). Nests of C. frenchi have been found in Eucalyptus and Araucaria cunninghamii. Ent_62_Coptptermes_spp.doc Page 2 Distribution Both subterranean termites are native to Australia. Coptotermes acinaciformis has been collected in all states except Tasmania, and C frenchi is known from South Australia, Victoria, southern Queensland, and the Australian Capital Territory. The first discovery of these termites in New Zealand was in Auckland during the 1 930s. In New Zealand, subterranean termites have always been found associated with Australian hardwoods imported mostly before adequate timber inspection services existed. Even though such timber has been used throughout the country for power and telegraph poles and railway sleepers, and, less recently, provided tramway sleepers in cities and boroughs, Australian subterranean termites have been found only in the North Island. Most discoveries have been made in Auckland City and adjacent boroughs, and in the Bay of Plenty. Other occurrences have been at Rawhiti in the Bay of Islands, Whangarei, Whangamata in the Coromandel Peninsula, at Waipoua in Poverty Bay, near Ruatoria, and in Hamilton, New Plymouth, and Wellington. As almost all sites are at low altitude near the coast, mildness of climate seems to determine where imported colonies can survive. When a colony is discovered the New Zealand Forest Service arranges its destruction. Only three sites – one near Te Puke, and two in Auckland – are known to still have active subterranean termites, and all these sites are currently under treatment. Economic importance In Australia subterranean termites cause widespread damage to living hardwood trees, principally eucalypts, which become unsuitable for milling because of the galleries excavated in them. Undetected colonies which survive tree felling and milling often remain active in timber used for poles and sleepers. Up to now, plantations of exotic conifers in Australia have escaped attack, although C. acinaciformis has been found in dead trees and stumps of Pinus radiata (radiata pine). Both termite species have become well-adapted to urban and industrial situations where they eat hardwood and softwood framing and sheathing timbers, poles, posts, and bridge and wharf timbers. Coptotermes acinaciformis also attacks horticultural and ornamental trees, vines, and shrubs, and has damaged such inedible items as plastic- and lead-sheathed electricity cables, and agricultural piping. Annual financial losses caused by C. acinaciformis in Australia have been estimated at many millions of dollars. Fig.4 - Diagram of Subterranean termite colony showing under-ground tunnels and earthen- covered runways leading to additional food sources. In New Zealand subterranean termites have caused considerable damage to buildings which they have invaded via tunnels from nests in nearby hardwood poles. They have not yet been found in Ent_62_Coptptermes_spp.doc Page 3 pine or eucalypt forests but they could be as important a pest here as they are amongst eucalypts in Australia. Description The social organisation and cases in a colony of Coptotermes are similar to those of the New Zealand drywood termite Kalotermes brouni (Leaflet No.59). However, whereas all drywood termite young (or "nymphs") eventually become winged reproductives, a great proportion of nymphs in a Coptotermes colony remain perpetually immature. These are the workers which excavate wood and soil, tend eggs and young, and feed the king and queen, the developing reproductives, and the soldiers. The workers are the most numerous caste in a colony. The relative numbers in each caste is controlled by hormones present in droplet exudations produced by the queen and passed around by the workers which groom her. The workers (Fig.5) are pale yellow, reach a length of 5 mm, and are blind. The head is round when seen from above and somewhat flattened. The black jaws protrude slightly, and the antennae have 15 or 16 segments. Fig.5 - Subterranean termite workers. Fig.6- Subterranean termite winged reproductives. Some nymphs grow wing buds which become larger each time the skin is shed. These nymphs are larger overall (6.5 mm) than nymphs without developing wings, but are otherwise similar in shape. During wing development the head and upperside of the body become darker and eyes appear. When fully grown these individuals are the winged male and female reproductives (Fig. Ent_62_Coptptermes_spp.doc Page 4 6) which emerge, disperse in mass flights, pair off, and attempt to found new colonies. The heads and bodies of these reproductives are brown, and the antennae are yellow. Body length is about 7.5 mm. There are two sets of slightly brownish wings which at rest lie flat over the abdomen and project about 4 mm beyond its apex. The leading edges of the wings are thick and cream coloured. After the nuptial flight the wings break off along the lines of weakness at their base. Young nymphs of either sex, and even nymphs with partly-formed wing buds, can develop into blind soldiers (Fig.7). These are up to 6 mm long, with a yellow to pale brown, slightly pear- shaped head, and black, curved jaws. There is a circular opening or "fontanelle" on the forehead (Fig.8), and from this a sticky, white, acidic fluid is exuded and used in colony defence. The fontanelle and its secretion occur only in subterranean termites and distinguish Coptotermes soldiers from those of other termites in New Zealand. Fig.7- Subterranean termite soldiers.. Life history and habits Little is known about the life history of Coptotermes in New Zealand. All colonies found here have been directly associated with imported Australian hardwoods and may survive for 20-30 years in this material before more food supplies are required. At this stage underground foraging tunnels and, if necessary, mud-covered runways are constructed. Colonies in New Zealand have often been large enough to produce winged reproductives, with flights taking place between early September and late December. However, there is no evidence that colonies have ever become established here from such flights. In Australia colonies can contain over 1 million individuals and produce 60 000 winged reproductives in a year. Flights often take place at dusk in association with rainy or stormy weather, and winged reproductives from different colonies over large areas of country may emerge at the same time. When new host material is found a male and female pair start to tunnel in before they mate. The female is the queen of the new colony and her abdomen becomes enormously enlarged as egg production increases. At first all young are workers; up to 2 years may pass before winged reproductives are produced and 3 years before there are any soldiers. Nymphs originally destined to remain immature workers can become winged reproductives or soldiers at a later stage should the colony be disturbed or partially destroyed. If the queen should perish certain of the immature nymphs may develop into wingless reproductives and produce eggs for the maintenance of the colony. In the warmer parts of Australia Coptotermes may construct nest mounds which can be up to 3 m tall. Nests may also be present in stumps or living trees. In trees nests have been found up to 9 m above the ground, but contact with the soil by galleries or covered runways is always maintained.