Wasp import set to save Christmas Island

La Trobe scientists have identified a new weapon in the fight against destructive crazy ants on Christmas Island – a tiny Malaysian wasp that will limit the ants' food supply.

Parks Australia and La Trobe University plan to import the micro-wasp, called Tachardiaephagus somervillei, to Christmas Island later this year, pending final government approvals.

Dr Peter Green, head of Ecology, Environment and Evolution, is the lead researcher. He said this biological control project aimed to protect the red crabs by cutting down the crazy ants' food supply.

"The territorial ants view the crabs as intruders and attack them with deadly acid. As a result, we've not only seen a huge drop in crab numbers but also significant changes to the rainforest," Dr Green said.

"The crazy ants live off a sugary substance called honeydew, produced by a single type of scale insect. This micro-wasp preys on that scale insect, killing it by laying eggs inside it. By reducing the ants' food supply, we hope to interrupt their breeding, and potentially stop them from building their devastating super colonies.

"Other types of micro-wasps are already used extensively for biological control on mainland Australia and overseas, so we know this can be safe and successful. We'll be monitoring the roll-out carefully and we hope to see results within two to three years."

The innovative conservation project is based on more than five years of research, confirming the micro-wasp is safe for people, pets and native wildlife. The tiny insect doesn't sting or build nests, and is very similar to a species that already lives on Christmas Island.

Director of National Parks, Sally Barnes said this new approach should be a life saver for Christmas Island's wildlife – including the iconic red crabs.

"When crazy ants first started forming destructive super-colonies in the 1990s, they wiped out tens of millions of red crabs on Christmas Island and had a devastating impact on native species," Ms Barnes said.

"The red crabs are the keystone species for Christmas Island, so it's crucial that we protect them.

"Until now, our only option has been intensive baiting with fipronil to kill the ants. That means dropping baits from choppers and sending squads of rangers out to bait by hand – a very costly exercise that has to be repeated every few years.

"Five years ago, we commissioned La Trobe to find a safe and effective long-term solution, and this micro-wasp is the answer."

Media contacts:    

Leah Humphrys (La Trobe University)

Mali Stanton 0439 582 686 (Parks Australia)

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