Baiting Techniques for Control of Coptotermes Species Within Existing Buildings in Australia

Baiting techniques have been developed over the years to control Coptotermes species, the most economically important termite species in Australia. Given the restrictions on organochlorines as termiticides in North America, this paper highlights research that has focussed on baiting programs against Coptotermes as alternatives to current control measures: drenching soil with pesticides or fumigation of entire structures. Details of the baiting procedures, toxins used, and their suitability for use in eradicating Coptotermes infestations in existing buildings are described. Suggestions are offered for the direction in which future baiting techniques may prove productive. --------------------------------------------------------------------------In Australia subterranean termites cause most of the termite damage to timber in service (French 1986). Of these termites, the most economically important are the Coptotermes species. Inarguably, protection from subterranean termites has come to depend almost entirely on soil barriers (Lenz and others 1988), with the use of toxic, persistent chemicals such as organochlorines and the organophosphate chlorpyrifos. Dusting termites in galleries and sheltertubes with arsenic trioxide is still permitted and is normally the first step in eradicating subterranean termites from existing buildings, followed by a soil treatment. The risk to the public of these chemicals is underrated, and partially unknown. Yet for the last 20 years these treatments have been standardized and recommended for use by local governments and the pest control industry (see Australian Standard (AS) 2057-1986; AS-2178-1986). The application of these persistent organochlorines as chemical soil barriers has ecological and practical limitations, as was pointed out by Beard (1974). There are many situations within existing buildings that render their use and application impracticable. For instance, termites infesting timber in apartments above the ground floor level are difficult, if not impossible, to control with the conventional chemical barrier treatments. 1 Presented at the Symposium on Current Research on Wood-Destroying Organisms and Future Prospects for Protecting Wood in Use, September 13, 1989, Bend, Oregon. 2 Principal Research Scientist, CSIRO, Division of Forestry and Forest Products, Graham Rd, Highett, Vic. 3190. Australia. Many dusting treatments using arsenic trioxide fail to destroy the whole termite colony, because too few termites are "dusted," and these do not return to the nest. Thus, the damage continues. Furthermore, there is a lack of scientific data to indicate precisely how effective all these chemical treatments are in controlling subterranean termites in both the urban and rural environments. Alternative treatments are virtually unknown. The outcome is that the pest control industry in Australia (and the United States) has fewer and fewer options. Apart from the physical nature of organochlorines, misuse of persistent termiticides by the pest control industry and increased public awareness of persistent home contamination and human exposure to organochlorine termiticides have contributed to these chemicals being severely restricted or banned in some countries around the world. In North America, the main manufacturers have voluntarily ceased production of organochlorines, whereas in Japan, organochlorines are banned, and only the organophosphate, chlorpyrifos (=Dursban), and several synthetic pyrethroids are registered for termite control. French and La Fage (1989) outlined the various treatments used around the world against the most economically important subterranean termite species. Although I am aware of the need to refine effective and environmentally safer substitutes for organochlorines and arsenicals in termite control, this paper presents the results of some experiments carried out in southeastern Australia over the past decade, and offers some practical refinements regarding arsenic trioxide treatments, and alternatives (such as bait systems) to the pest control industry. I hope that some of these techniques may be adapted for North American conditions. In Australia, I have concentrated on the use of baits to aggregate termites (in this paper, the term 'termites' refers to subterranean termites' unless otherwise mentioned) in mounds and those that are infesting buildings, and the judicious use of small amounts of toxins to kill these colonies. The toxins referred to in this paper are arsenic trioxide and mirex. The efficacy of mirex against termites in North America was demonstrated by Esenther and Gray (1968), Beard (1974), Esenther and Beat (1974, 1978, 1979) and Esenther (1979). In Australia, Paton and Miller (1980) found that less than 1 g of mirex was required to kill a colony of the Giant Northern termite (Mastotermes darwiniensis Froggatt), whereas French (unpubl. data) found that less than 0.25 g mirex was effective against a colony of Coptotermes lacteus (Froggatt). By way of contrast, an average 15 square building (1 square = 10 ft2) necessitates about 3 kg of active ingredient (i.e., organochlorine or organophosphate), using the Australian 46 USDA Forest Service Gen. Tech. Report PSW-128. 1991. Standard, whereas less than 1 g of mirex in wood-decay bait-blocks can suppress an active Coptotermes acinaciformis (Froggatt) colony in a building. Although mirex is considered a carcinogen by some and has been banned in North America, there has been no report of injury to a person by mirex, and the chemical has not been measured in persons with occupational exposure to the compound. Mirex is currently registered under special permit to licenced pest control operators (PCOs) for controlling M. darwiniensis in north Queensland, the Northern Territory and northwest Western Australia. I am currently negotiating with the Victorian and New South Wales State Governments to allow the use of mirex under a special permit by licenced PCOs. There are two main areas to apply baits against termites: (a) within and under buildings, and (b) around buildings, in termite mounds and in termite-infested trees. Prefabrication of the bait-containers is similar for both situations. However, whether inside or outside the building, location of active termites is the single most important factor. There is no substitute for a thorough and careful search in and around a building to locate active termite sheltertubes or galleries. Sometimes the termite nest may be located either in an above-ground mound or in a standing tree or stump. Regardless of the location, the following procedures for aggregating Coptotermes species in bait-containers have been used. Although the application of the toxin may vary, the aim of this control technique is to destroy an active termite colony with a slow-acting stomach poison that will be distributed throughout the colony by foraging termites. ARSENIC TRIOXIDE BAIT CONTAINERS