New Zealand scientists have begun trials to test the effectiveness of some natural pesticides on one of the world's worst vegetable pests, the diamond back moth.
The moth caterpillar causes serious damage to brassica crops such as broccoli, cabbage, cauliflower and bok choy.
More than a billion dollars a year is spent on trying to control the pest. The moth quickly becomes resistant to whatever chemical pesticide is used on it.
Scientists working under the Bio-Protection Research Centre based at Lincoln University, with the backing of genetic specialists at New Zealands Genomics, have been trying a non-chemical biological approach.
They have been investigating the potential of using several native fungi and bacteria in bio-pesticide sprays.
The centre's director Professor Travis Glare said work was well advanced and they were two weeks into a 16-week field trial.
"We've identified several bacteria and one species of fungus that show real promise.
"We've actually got a new programme funded from the government called the next generation bio pesticide programme, a Bioprotection Research Centre programme that has AgResearch staff in there and Lincoln University and Plant and Food staff.
"And we are combining our best (biological control) agents and using them in a field trial against diamond back moth."
Professor Glare said the use of a combination of biological agents to control pests was also different from the single solution approach taken with chemical pesticides.
"The traditional appraoach to using biopesticides is really very much to mimic what you would do with a chemical pesticide, so you produce one organism and then you spray it out.
"Our work in the Bioprotection Research Centre has highlighted that really, nature does things through combination. It rarely uses one agent to get to an end point. And so this sort of silver bullet approach we've been looking for, for years, is probably not the best way to go.
"And so we're looking at these combinations of agents to see if using different combinations of bacteria and fungi together, will have a greater effect than using any one by itself."
Professor Glare said bio protection researchers also looked for agents that would control more than one pest.