Radio New Zealand - Te Reo Irirangi o Aotearoa

Research shows invasive ant populations often die out

Updated at 7:51 am on 1 December 2011

Victoria University scientists have found that invasive ant populations often die off without human intervention.

They say that offers the potential for big savings in biosecurity control costs, but warn it's too early yet to give up on eradication measures and let nature do the job.

The research has focused on Argentine ants, which invaded New Zealand more than a decade ago.

They're regarded as a serious agricultural and horticultural pest and millions of dollars have been spent on measures to eradicate them.

Researcher Phil Lester says the study has shown that Argentine ant infestations have often collapsed and disappeared without intervention.

He doesn't think climatic factors are involved and says diseases or parasites could be responsible.

Dr Lester says Argentine ants are well suited to much of New Zealand's climate, but they probably came into New Zealand from Australia and from one nest, which then spread throughout the country.

He says that means the genetic diversity of the ants is relatively low, which has been shown in other studies to make them more susceptible to pathogens and diseases.

Dr Lester says one of the key biosecurity implications is trying to figure out which species are likely to establish and then crash in their populations, or not have an economic effect as they might do elsewhere.

He says, however, that it would be too risky at this stage to leave the control of those pests up to natural forces.

Dr Lester says it would be good to get to the point where there was an arsenal of biological natural products able to target for invasive species that do become established.

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