No silver bullets for pest management
A crisis of pest management is coming shortly but there are no silver bullets, Travis Glare from the Bio-Protection Research Centre warned onion growers at the Onions New Zealand’s research seminar.
“If we didn’t have pesticides 83% of food would be lost at the production stage,” he said.
“But development of new sprays is more expensive now. Monoculture is the easiest way to farm but we are making a problem for ourselves.”
Glare said a leap of faith had to take place for growers to stop using chemicals, but large chemical companies were already buying biological companies because they saw the potential market size.
The Bio-Protection Research Centre is a national centre of research excellence, founded in 2003, which has six partner institutes: Lincoln, Canterbury and Massey Universities, AgResearch, Plant & Food and Scion. It focuses on fundamental research into natural, sustainable ways of protecting New Zealand from plant pests, diseases and weeds.
There were no silver bullets but user-inspired basic research would still be carried out with goals in mind.
“There are big questions such as why some strains of bacteria cause problems and some don’t?” he said.
“We need to know where evolution is going and steer it as we try to work out how everything interacts.” Glare said the centre tried to get a lot of science behind what it was doing.
“With weeds we want to know why they cause problems,” he said.
More than 25,000 plants had been introduced to New Zealand but only 2,523 had become problems.
“Is that because they escape from their enemies, evolution or some sort of hybridisation?
“It could be all three and we need to predict which ones may become problems.”
With parasitoids, he said one which controlled Argentine stem weevil was introduced in the 1990s.
“But it has started to become less effective and we are trying to work out why.”
The genome of the weevil had changed since it had been in this country due to rapid evolution, but the asexual parasitoid had not. While the parasitoid could be changed to be male or female they could not then be released as they could breed with the Sitona weevil and then become less effective on both insects.
More information was required on how plants and diseases communicated in order to breed plants with more resistance. But there were
practical issues about how to get antibacterial agents into plants.
“It’s a growing area and more than one organism can be used,” he said.
“But genetic engineering is waiting for public and trade acceptance.”
Work was being carried out with enhancing biocontrols as every plant had endophytes and there was the potential to use them to improve plant growth and insect resistance. Work was also being carried out with maize and brassicas trying to find new endophytes, but this was difficult with 15 types of fungi found on one maize plant when it was pulled up. >
“Gene editing could be used to take out one piece of DNA targeting plant breeding, but there were ethical questions as to whether this was genetic modification.”
Work was also being carried out on improving biologicals with overexpression of bacillus thuringiensis (BT) being investigated.
“By selecting clever cultivars bigger plants are the result and this can reduce disease impact,” he said.
Plants had microbes all around them, creating their microbiome, which large companies were interested in developing further.
“We have the tools to look at them,” he said. When it came to the application of control agents there was still a roadblock, but
a new precision agriculture technique, fogging, was an application technology which could be used.
“We can sequence every organism and look at any variations in growth around the country.”
Where biopesticides had been applied there had been some inconsistent results.
“Every plant is changing its own environment,” he said.
“Each grass grub population, for example, is a separate microbial community. We’re asking if we can use that and manipulate it to get them to eat roots, for example.”
Glare said a move was now underway from the genome to the proteomic area.
“The tools we’ve got now are fantastic and we’re getting to an era where the species is not important but the genome is,” he said.
Transgenic crops such as cotton and soya beans were the result of single action gene changes so it had been easy to get resistance. The next step would be to move on to more than the top five crops around the world.
Gene editing could be used to take out one piece of DNA targeting plant breeding, but there were ethical questions as to whether this was genetic modification.
Gene drives had only been carried out in laboratories, where a modified organism was released into the population and drove it to extinction.
“But they will repair themselves,” he said. “There are still a lot of technical issues. We have to make a transgenic organism to do this and that’s not possible at the moment. We also need an idea of population genetics because it won’t be as effective in some systems.”
Asked by a grower about hypervirulent strains emerging he said he didn’t know how this would happen.
“If any organism is too virulent it kills all its hosts and then dies out itself.”
Drones, which he described as “the de rigueur [fashionable] idea of how to do better agriculture” were able to monitor plant health as well as carry out very targeted spraying.
“The technology is there and it’s going to happen quite rapidly,” he said.
Precision agriculture application could be used in complex growing systems.
“You don’t need to use an expensive spray on the whole paddock, just where the problem is.”
Better understanding of microbes which were hard to see and complex, could be gained by mescosm study, an outdoor experimental system which measured everything happening to a plant under controlled conditions. An 18-month experiment was being carried out now at Lincoln University with broom, which it was hoped would unlock information as to why it was more invasive in some areas than others.
Glare said community involvement was also required in some research areas, as some questions kept coming up.
“It’s not the scientists’ job to answer these questions, we just put up the information,” he said.
“We also need to develop capability for a smart workforce as few New Zealand students go on to post-graduate studies.”
They often got jobs in industry quickly which at present meant 75% of post-graduate students at the centre came from overseas.
▴ Travis Glare – big questions to be asked.