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Toxic Implant

Published: 21 Dec 2016

Article from FAME Newsletter, 2016 Issue 2

What do you do when wildlife conservation groups like FAME try so hard to reintroduce Australia’s rare and endangered fauna and then you find feral cats, often as few as only one or two individuals, start killing and eating your valuable animals?

You try so hard to find the feral cat(s) doing the killing but it continues until you eventually succeed, or all the animals are eaten, or building an expensive cat-proof fence becomes the only feasible option. Maria is seeking to replicate historical accounts from south-west Western Australia of poisonous possums and bronzewing pigeons killing feral dogs and cats due to the 1080-producing native Gastrolobium plants enabling secondary poisoning of predating or scavenging introduced predators.

A very small capsule called a “population-protecting-implant (PPI)” is being developed to remove from the cat population the most adept predators, those doing the killing of our reintroduced animals, giving the survivors amongst the released animal population a chance to establish and re-populate the area.

Thanks to the collaborative research of University of South Australia Swiss polymer chemistry Masters student, Martin Rauber, the prototype implant is a combination of polymers stable in the neutral pH (~7.0) found under the skin, but unstable in the acid pH (~2.0) found in the stomach of the predators. The capsule would be inserted under the skin of the native animals before they are reintroduced, and will only be activated if the animal is predated.

In the acidic stomach the acid-sensitive polymer will degrade and release its 1080 contents, be rapidly absorbed into the predator’s bloodstream, quickly killing it and stopping it killing additional native animals.

Compared to a registered feral cat bait, these implants should allow us to use half of the 1080 dose currently used, thus overcoming our difficulties in getting the feral cats to eat a bait when there are animals to eat instead, and only targets the cats doing the killing. As a conservation tool we would suggest it should provide significant advantages over those available to date.

Maria’s project involves determining the stability and safety of the implants (PPI) in experiments with mice and rats, the efficacy of their use in native mammal reintroduction projects in experiments planned at Arid Recovery, and assessing the risk of the implants to off-target species.

Maria-Olga Bargsted Aravena

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