Black beetle biopesticide a step closer

Black Beetle

A product containing a natural insecticide to fight one of New Zealand’s worst agricultural insect pests is a step closer following several years of successful research and trials by AgResearch.

Research into the product, that is infused with the naturally-occurring bacteria Yersinia entomophaga (Ye), will shortly begin its second stage which includes investigating the optimum application rate and production scale-up.

AgResearch Senior Scientist Dr Mark Hurst says that if successful the product would have a significant impact on black beetle populations which cannot be effectively controlled by insecticides in established pasture. It’s a great example of an effective biopesticide – a natural pesticide based on micro-organisms or their bioactives. These are targeted as well as safe for the environment and humans and can provide solutions to many insect pest and disease problems. Consumers around the world are demanding sustainable, safe food and New Zealand producers are responding by adopting well proven alternatives to chemical controls as they become available

Black beetle (Heteronychus arator) is found in warm areas of the North Island with root feeding larvae capable of severe pasture damage. A series of very dry summers and autumns over the last three years has contributed to a population explosion.

The product is based on the Ye bacterium that was discovered in 1996 in a grass grub corpse during a search for alternatives to chemical pesticides such as organophosphates, which are being phased out. Ye releases toxins that ‘burst open the gut’ of the insect and cause rapid death, says Dr Hurst, who led the research team.

“The biopesticide is very good at killing a large variety of insects, especially beetles and moths. It doesn’t, however, harm earthworms, honeybees or other beneficial organisms,” he says.

Senior Scientist Michael Wilson says that trials carried out in autumn and spring last year gave very encouraging results and suggested that spring might be the optimum time to utilise the product.

“In spring you kill the adults before they lay eggs so you get fewer larvae hatching and it’s actually the larvae that do most of the damage. It’s difficult to target larvae directly with a biopesticide because they are underground, in the soil, so hitting the adults in spring is probably the way to go,” Dr Wilson says.

Dr Hurst says that now the product has been proven to work well in the field, more research will be undertaken on wider issues around the best methods for manufacture and application. “Ideally, what we want to do now is start investigating ways it could be applied using existing farm machinery.”

Meanwhile, entomologist Sarah Mansfield has undertaken aligned research investigating the movement and feeding behaviour of black beetles to help create the most effective delivery technique for the product.

Research into biopesticides is ongoing in the Next Generation Biopesticides Programme (NGBP), a joint initiative between AgResearch, the Bio-Protection Research Centre (Lincoln University) and Plant and Food Research with funding from the Ministry of Business and innovation and industry partners Ballance Agri-Nutrients, Grasslanz Technology, Zespri and the Foundation for Arable Research.

NGBP leader Dr Maureen O’Callaghan says that when combined, all the research points to significant advances being made and a user-friendly biopesticide product being much closer.

“The very promising results achieved in the field trials are the result of excellent collaboration between researchers, industry partners and farmers.”

Development of the product has been supported by Ballance Agri-Nutrients and the Ministry of Primary Industries via their PGP programme, along with DairyNZ.

“Progress has also depended heavily on the enthusiastic support of Waikato farmers who have hosted field trials on their farms as part of several Sustainable Farming Fund projects focussed on controlling pests,” she says.

The researchers note that the biopesticide product can used in conjunction with other techniques to help control black beetle. Currently farmers can take a range of preventative measures including sowing insecticide-coated seed to provide seedling protection at a critical time; the grass is germinating at a time when the black beetle adults have just emerged from the soil.

Farmers can also use ryegrass cultivars containing the novel endophyte AR37. Novel endophytes have also been shown to give protection against other pests such as Argentine stem weevil. However, endophytic grasses can’t always prevent pastures from becoming infested with black beetle and additional control measures such as the biopesticide product are needed.