Dick Murray, technical manager of Syngenta’s Professional Pest Management division, takes an in-depth look at Altriset termiticide, examining the trial data and the product’s mode of action.

Non-repellent liquid termiticides have gained popularity because the delayed mortality caused by non-repellents allows them to impact the subterranean termite populations.

In contrast, the application of repellent termiticides, such as the repellent pyrethroid or fast knockdown organophosphate termiticides, do not usually impact the overall population of termites and thus the surviving colony continues to produce foragers and alates that can further infest nearby areas.

Even within the non-repellent termiticides, some chemicals kill the termites too quickly, preventing them from being effective toxicant carriers – termites dying in the tunnelling system or inside infested wood can act as a repellent barrier to other termites, resulting in the areas being ‘sealed off’ and thus further transfer is not possible. As such, the delayed mortality of a non-repellent like Altriset, can offer very real benefits.

Much work has been done with Altriset in Australia to determine the transfer behaviour and the practical importance of delayed mortality, that together lead to termite colony elimination.

Trials near Sydney demonstrated that initial doses of Altriset in soil may be sub-lethal and cause worker termites to rapidly cease feeding, but these workers may continue to tunnel for 7-14 days without aversion to subsequent exposure of the treated soil. This means that exposed termites continue to travel through the treated soil for 7-14 days until a lethal dose is reached. This enables the spreading of Altriset to nestmates through trophallaxis and social grooming, which results in colony suppression and elimination.

The ‘stop feeding’ effect of Altriset is well known, so these exposed termites are likely to be starving. Healthy nestmates will attend to them, as is the natural behaviour of termites and this further facilitates transfer. All these characteristics contribute to proven colony elimination.

Extensive field trials carried out by Further Research and Consulting near Townsville in North Queensland, with indirect soil trenching around mounds, showed treatment and colony elimination effects following exposure to Altriset. Termites exposed to Altriset show mottling, become lethargic and walked in ‘slow motion’. They were even observed on the surface of termite mounds until they become moribund and die. The resulting colony elimination clearly demonstrated the excellent transfer properties of Altriset.

In addition to these studies, there are ongoing nationwide soil residual trials that commenced in 2007. These soil residual trials and tunnelling studies show that even after seven years, there is still enough Altriset present in these soils to affect foraging termites – termites show the same stop feeding and transfer effects when exposed to the seven year old treated soil.

Australia-wide house trials were initiated in 2009 on over 30 termite-infested houses. These initial house trials did not involve the direct treatment of termite activity inside the building – only a perimeter trench treatment was carried out to get an indication of the ability of the Altriset treated zone to stop the infestation.

Wall void Coptotermes nest, pre-Altriset indirect soil trenching perimeter barrier

Timber pest inspections following the treatments to these houses showed elimination of activity in 75% of the treated houses at 30 days with activity in the remaining 25% being eliminated by 90 days. Elimination of activity within the structures could only have been delivered through the delayed action and excellent transfer properties of Altriset. Based on the Townsville field trial results, it is quite likely that colony elimination was also achieved in many cases.

Colony elimination at 7 week inspection, post-Altriset indirect soil trenching perimeter barrier

In an additional five houses that were pre-treated with Altriset or Arilon foam (direct treatment to active termites) and then followed up with an Altriset soil treatment, elimination of active termites was achieved within 30 days after treatment. There have been no breaches to any of the Altriset barriers in these houses.

Since registration of Altriset in 2011 there have been thousands of properties treated commercially around Australia, providing us with real world evidence of the longevity of residual Altriset in soil and field trials provide proof of termite colony elimination following treatment with Altriset. It is the combination of stopping termites feeding, excellent transfer properties and delayed mortality that leads to colony elimination and ultimately that should be the aim of all termite treatments.

Dick Murray, Technical Manager, Professional Pest Management, Syngenta Australia