It’s like a scene out of the movie “Jaws.”
The intrepid scientist reaches his hand into the gut of a shark and pulls out what it had for dinner — a different fish or maybe, in the case of sharks, a tin can. He knows, just by examining those contents, what this predator likes to eat.
Only this is real life, and the scientist in this case is Boyd Mori. The predator whose dinner he wants to discover is a spider, not a shark. And the tools he’s using to reach into its belly are much more precise.
“We want to know which beneficials are the most beneficial, and by using this next-generation DNA sequencing approach, we can determine what a predator insect is feeding on,” said the University of Alberta researcher.
“We want to know what they’re eating and what impact they could be having on our pest populations. We assume they’re having an impact, but we don’t know for sure.”
In the past, research into beneficial insects — that is, ones that eat the pests that feed on crops — has mainly focused on specific predators or pests. Researchers might have looked at whether certain parasitoids were present in the field or if generalist predators like beetles were eating a certain pest.
“Before, we would design DNA primers that would help amplify the pest DNA within the beetle,” said Mori. “So if the predatory beetle had eaten the pest species and the DNA of the pest species was present, the primers would tell us that.”
But in this new research, which will kick off this summer, Mori’s team will be using next-generation DNA sequencing with universal primers to sift through the entire stomach contents of generalist predators such as beetles and spiders to discover their preferred entrées.
“We’re not specifically looking for one pest over another. We’re looking at every insect species that beetle has eaten.”
Using these universal primers gives the researchers more sequencing results than they would normally get with traditional approaches.
“By doing this with field-collected specimens, we don’t have any prior knowledge of what it could potentially be eating. This technique will allow us to identify the items it’s feeding on.”
And generalist predators like beetles and spiders are the primary focus of this research because of the “ecosystem services these insects provide,” Mori added.
And they’re present in almost every single field.
“If we can find a predator that has a specific affinity to feed on, say, wheat midge larvae, it will help us identify which predators have the most bang for their buck on the insect pests. Then we can start looking at some of our agronomic practices to see how they affect the predators.”
And that’s the ultimate goal of this research — to reduce reliance on insecticides by maintaining beneficial insect populations, he said.
“What can we do to increase these predator populations in the field? That’s what we’re hoping to learn — if we can identify which predators are the most beneficial, then in the future, what can we do to enhance those populations in the field?”
Beneficial insects are often wiped out alongside pests as a ‘non-target effect’ of a pesticide application. But increasing the level of beneficials in the field could reduce the need for pesticides in the first place — or at least that’s the hope.
“If we can really enhance our beneficial insects in our fields, there is the potential that they’d help to reduce our pest populations so we no longer have to apply external inputs. That’s the ultimate goal,” said Mori.
Farmers are already doing a lot of the right things to maintain beneficial insect populations, Mori added. This research will just give them another tool to tackle insect pests in their fields.
“A lot of best management practices have been designed around beneficial insects,” he said. “By using our economic thresholds and only applying insecticides when absolutely necessary, it really helps to conserve not only the predators and the parasitoids in the field but all the other species that could be enhancing the soil.
“Farmers are doing a good job of that. We just want to help them with this research to do even better.”