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Tucking into Tongariro heather

Heather (Calluna vulgaris) was deliberately introduced into New Zealand, on the Central Plateau of the North Island, from 1912 to 1923 in an attempt to re-create Scottish grouse moors. By the 1990s it had spread to cover around 60,000 hectares of land in what is now Tongariro National Park.

The heather beetle, Lochmaea suturalis, was first brought into New Zealand to try to tame the invasive plant in 1996, but the beetles took a long time to establish and initially failed to thrive, with only one population surviving.

Manaaki Whenua researchers Paul Petersonand Simon Fowler have now mapped the spread of that beetle population in the park, and found that the beetles have spontaneously spread several kilometres away from known release sites. The mapping shows that vast areas of heather have been affected by the beetles over the past three years, with approximately 20,000 hectares now remaining. As a reflection of the success of the beetles, the NZ Defence Force no longer has to spray herbicide over large areas of its Waiouru Military Training Area adjacent to the Park.

The researchers now plan to check higher-altitude sites that are harder to access to see how high beetles can thrive. Research will also investigate whether any environmental changes over the past 25 years, or a genetic adaptation, have contributed to the recent spontaneous increase in beetle populations.

Researchers are also revisiting sites to monitor if the heather recovers after beetle attack, and if so, how quickly. So far the signs are good that the beetle can rediscover recovering heather and repeat its demolition job.

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