Posts Tagged ‘Department of Conservation’

Endangered beetle faces ‘unholy alliance’ of rabbits and redbacks

An “unholy alliance” between rabbits and Australian redback spiders is threatening the existence of an endangered New Zealand species, a study led by AgResearch has shown.

Carried out with the Department of Conservation (DOC) and University of Otago, the study has illustrated the struggle for the ongoing survival of the Cromwell chafer beetle – a nationally endangered native species that can now be found only in the 81 hectare Cromwell Chafer Beetle Nature Reserve between Cromwell and Bannockburn, in Central Otago.

The study found numerous rabbit holes that provided shelter for the rabbits were also proving ideal spaces for the redback spiders to establish their webs. Investigation of those webs in the rabbit holes found the Cromwell chafer beetle was the second-most commonly found prey of the spiders.

These findings “give a fascinating insight into the almost accidental relationships that can develop between species in the natural world, and how that can impact on other species,” says AgResearch Principal Scientist Dr Barbara Barratt.

As a result of the research, DOC has carried out a programme to break down old rabbit holes and hummocks in the reserve to destroy spider nests, and does regular rabbit control. An annual survey for beetle larvae with AgResearch will show whether these actions are having an effect.

Beetle larvae will be surveyed next summer to see what effect reducing redback spider nests is having on the Cromwell chafer beetle.

The Cromwell chafer beetle (Prodontria lewisi) is a large flightless beetle that lives underground in the sandy soils of the Cromwell river terrace. In spring and summer adult beetles emerge from the ground at night to feed on plants and to breed.

Radio NZ reports on biocontrol and the fight to eradicate bad weeds

Radio NZ has been reporting on the problem of weeds, both in native vegetation and on farms and orchards, and on the the Department of Conservation’s War on Weeds.

One interviewee was Hugh Gourlay, from Landcare Research, who discussed (here) his work as part of a team that works to find biocontrol agents to kill or knock back the worst weeds.

The work involves visiting the country of origin of a plant and hunting for diseases that infect it. The team is  also looking for insects that attack and eat any part of the weed, including the seeds, flowers, leaves or stems.

Hugh told Radio NZ it is sometimes possible to “knock a plant invasion on the head” with prompt action to hunt down and kill all the plants. Chemical control, using herbicides, is usually the next step, but at best it will “keep the problem at bay.” This leaves biocontrol as the best answer for widespread weeds.

Once potential biocontrol agents are identified they are imported into New Zealand and kept in strict quarantine, so they can be tested to see if they attack any plants other than the weed. “If they don’t attack anything else then we can look to release them.”

Describing some great biocontrol successes in New Zealand, Hugh cites St Johns Wort control in the 1960s as a “guiding light” success story. Ragwort (Jacobaea vulgaris), some thistle species and mist flower (Ageratina riparia) have had successful biocontrol agents introduced.

More recently, the broom gall mite and several species of beetle that attack Tradescantia have been showing great promise.

Darwin’s barberry is among Hugh’s recent projects.

“Darwin’s barberry continues to advance across the countryside in Otago and Southland. It takes over entire hillsides, and becomes quite a monoculture.”

Beginning in the early 2000s, the biocontrol team identified a seed weevil and a flower weevil in the plant’s native range in South America. The focus has been on the seed weevils, which have been released over two years.

Radio NZ’s “Our Changing World” recently featured a story about the wasp mite that is being investigated as a potential wasp biocontrol agent. It has also looked at the buddleia leaf weevil.

Biosecurity warning sounded: new pastures may create future weed threat

Breeding new fast-growing grass varieties that produce more seeds and are resistant to drought, pests, grazing and disease may inadvertently be creating the next generation of invasive weeds, an international team of researchers has warned.

As the global demand for dairy and beef escalates, farmers are increasingly seeking ways to reap greater productivity from their pastures.

The problem, according to Philip Hulme, Professor of Plant Biosecurity at Lincoln University and lead researcher at the Bio-Protection Research Centre, is that in making grass varieties more robust, they are more prone to becoming a problem for the environment.

The researchers have made four biosecurity recommendations for government, industry and researchers.

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Challenge boosts protection of biological heritage

The National Science Challenge, New Zealand’s Biological Heritage Nga Koiora Tuku Iho, is to receive funding of $25.8 million over five years for research to protect and manage the country’s biodiversity, improve biosecurity and enhance resilience to harmful organisms.

Science and Innovation Minister Steven Joyce says the Challenge spans a wide range of scientific disciplines and will include researchers from nearly all New Zealand’s relevant research institutions.

The Challenge will be hosted by the Crown research institute Landcare Research. It includes researchers from the other six Crown research institutes and all eight New Zealand universities.

It also draws on research expertise of Te Papa Tongarewa, the Department of Conservation, the Ministry for Primary Industries, regional councils and Ngāi Tahu.

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