Novel microbial seed treatments protect wheat seedlings from insect damage

AgResearch scientists involved in the Next Generation Biopesticides Programme are following promising leads to identify effective environmentally benign microbial seed treatments for use by arable farmers.

These treatments are based on soil bacteria that have been isolated from New Zealand pastures and shown to kill grass grub. The grubs are significant pests in autumn sown cereal crops and crops that follow pastures in a rotation are particularly at risk when the pasture has harboured high numbers of grass grubs.

Insecticide seed treatments are common practice to protect seedlings against root feeding insects but many insecticides will be phased out in coming years so alternative solutions are needed for growers.

Microbial insecticides, or biopesticides, can be effective alternatives to chemical insecticides in many situations. Inoculation of seed with insecticidal microbes places the microbe close to the plant roots where the target pest feeds. This ensures rapid contact between the microbe and the pest. There is increasing interest globally in development of microbial seed treatments.

Programme leader Maureen O’Callaghan says that since 2012, FAR and AgResearch, with support from the Ministry of Primary Industry’s Sustainable Farming Fund, have been testing microbial treatments of wheat seed on commercial farms in Canterbury for their ability to protect seedlings from grass grub attack.

“Seeds treated with insecticidal bacteria resulted in higher yields than untreated seeds where grass grub was present, and in some years these treatments were as effective as current insecticide seed treatments,” Dr O’Callaghan says.

“These trials have demonstrated that microbial seed treatments can protect cereal seedlings effectively from grass grub attack and suggest that further work and investment to scale-up microbial seed treatment processes is warranted.”

Photo: Richard Chynoweth, FAR

Background on the Next Generation Biopesticides Programme

The Next-Generation Biopesticides programme aims to find new, safe and sustainable solutions to New Zealand’s key insect pest and disease problems.

Globally, primary producers are under increasing pressure from consumers and governments to sustainably and ethically produce safe foods and food ingredients. The gradual withdrawal of chemical pesticides will leave growers with few or no alternatives to control pests and diseases that can cause major production losses. Effective biopesticides are needed to control existing pests and diseases, and those emerging as a result of land-use change, farming intensification, climate change and biosecurity breaches.

Biopesticides are natural pesticides made from microorganisms (bacteria, viruses, fungi, protozoa and nematodes) or their products.

Our aim is to retain or improve productivity in New Zealand’s pastoral, horticultural and arable sectors, and help meet market demands for sustainably produced food. To increase uptake of biopesticide products, we are consulting with industry representatives to ensure our biopesticides meet the needs of end users and are:

  • targeted, sustainable and environmentally friendly
  • safe for food use and human health
  • effective and easy to use

We are targeting some of the most financially damaging pests and diseases affecting New Zealand farming and horticulture. Our initial research targets have been determined in consultation with our industry partners, and include:

  • Kiwifruit disease caused by Pseudomonas syringae pv. actinidiae (Psa)
  • Pasture pests, such as African black beetle, porina caterpillar and plantain moth
  • Forage and vegetable pests, such as diamondback moth
  • Pests and diseases of maize.

The research programme is a joint initiative between AgResearch, the Bio-Protection Research Centre and Plant & Food Research and is funded by the Ministry of Business, Innovation and Employment until 2020. Our industry partners include: