Farm Forestry New Zealand
PESTS AND DISEASES OF FORESTRY IN NEW ZEALAND
Subterranean termites – the hidden enemy
From Biosecurity Issue 22 , September 2000.
Australian subterranean termites (Coptotermes acinaciformis) probably hitchhiked into the country unnoticed several decades ago, within Australian telephone poles, railway sleepers and wooden packaging. Termites can cause significant structural damage to residential properties.
Response to termite incursions
As a result of the termite incursions, New Zealand border controls were stepped up to prevent further termite-infested material being imported. A Termite Act was passed in the 1940s to give trained inspectors the necessary powers to search for and eradicate termites. The Act was administered by the then Housing Corporation.
From 1940 to 1980, up to 50,000 properties in the upper North Island were inspected for subterranean termite damage, with around 110 infested sites successfully ‘treated’. Often, treatment involved the destruction of the power pole in which the termites lived.
In the late 1970s the Termite Act was repealed and responsibility for termite control was passed to the former New Zealand Forest Service. The Ministry of Forestry assumed the management of termite control in 1987. With the merger of the Ministries of Forestry and Agriculture in early 1998, subterranean termite management became MAF’s responsibility.
Otorohanga battling on
Currently, there are areas in New Zealand known to be infested with subterranean termites, and several other sites continue to be monitored. The most significant infested site that MAF is currently managing is in a suburban area of Otorohanga.
like light and build mud trails and piles for protection.
Since the infestation was first reported in 1990, various strategies have been employed in Otorohanga. The programmes undoubtedly helped control the termite infestation, but the ultimate goal – eradication – was not achieved.
Bait stations
The continued persistence of termites in Otorohanga led MAF to investigate alternative systems. In November 1999 a newly patented baiting system, developed in the United States, was deployed.
The bait station system is based on hexaflumuron, an insect growth regulator that interferes with the termites’ moulting. The bait does not act immediately it is ingested, which enables the termites to spread the poison throughout the colony without suspecting they’re under attack. Then, when it comes time to shed their external skeletons and form new ones – a process that happens every month or so – the new skeleton doesn’t form. Instead, the old one wraps around the insect, killing the termite. To date, 23 research studies have documented elimination of 87 out of 94 (93%) baited colonies in the United States, Australia, Japan, France and Malaysia using this system.
Otorohanga termites down – but are they out?
The bait station system in Otorohanga has been monitored monthly, with no new termite activity being detected now for six months. Overseas research shows that achieving three clear inspections indicates that the colony is eliminated. In New Zealand, MAF Forest Biosecurity is not yet convinced.
The Otorohanga bait stations will continue to be monitored for another 12 months, and further surveillance is likely to continue for several years.
New Zealand to host experts meeting
MAF plans to host a meeting of world experts on termite behaviour in early 2001. It will focus on the known New Zealand infestations and review response management techniques.
Australian awareness programme
A termite awareness programme was recently held in Australia, where up to 19% of houses are attacked and termites are estimated to cause more than $120 million in repairs each year. The programme involved a three-day conference on the management and control of termites. Participants included experts from Australia, United States and Malaysia and the latest termite control methods were assessed during the programme.
Native termites do little damage
New Zealand has three species of native termites. In terms of destructive capability, these are of little significance compared to the exotic termites. Native termites do not form large colonies and usually affect only a small part of any wooden structure.
Termite tips – did you know…
- Termites have existed for about 100 million years and are thought to be related to the cockroach.
- Most termite damage is invisible as they eat from the inside of timber outwards – rarely breaking through the surface.
- Termites play an important role in the ecosystem, breaking down wood fibre into organic matter.
- Subterranean termites are somewhat cryptic and secretive by nature, making field research of insect populations very difficult.
- The Formosan termite colonies in the United States can house up to 10 million insects.
Mark Ross, National Adviser (Forest Pest Surveillance and Response), Forest Biosecurity
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