Until now, live insects have been too wriggly to make good subjects for scientists wanting to understand more about insect innards. But an interdisciplinary team of biologists and imaging specialists from Western has worked out a novel micro-imaging solution that’s leading to unprecedented new ways of viewing insect development.
The team has created spectacularly detailed, three-dimensional views of insects’ insides – without harming the creatures in any way – by using carbon dioxide to place the insects into a state of temporary animation.
PhD candidate Joanna Konopka, an insect biologist, was looking for a way to examine more thoroughly the physiological life-cycle of live insects, including Colorado potato beetles and true armyworms. Both agricultural pests wreak havoc in crops across North America.
The standard scanning techniques – using dead insects or killing them during the imaging process – still leave crucial gaps in scientists’ understanding. “We essentially had snapshots, moments in time, when what we needed were dynamic images of insects’ internal development,” Konopka said. “We thought, what would happen if we tried to image them live?”
She teamed up with colleague Danny Poinapen, a biophysicist at the micro-CT lab at Robarts Research Institute, and together they developed a technique that builds on insects’ peculiar ability to withstand oxygen-low environments and high ionizing radiation doses.
They temporarily immobilized the insects with a steady flow of carbon dioxide, for as long as seven hours at a time, and again several days later. They found it was possible to scan for, and study, tiny changes in the insects over time – with no effect on the insects’ longevity, behaviour or reproductive abilities.
She said insects have an almost-inexplicable ability to survive intact for hours and even days without oxygen, in conditions that would leave a human with brain damage or death within minutes. In this instance, the carbon dioxide kept the insects in sort of a stasis while they were being scanned, and they recovered fully.
The resulting images are stunning, Konopka said. “I was absolutely awed. I thought, ‘Wow, this is cool.’ I’m familiar with pictures of drawings in books but this gives us a wholly new perspective of what they are.”
Said Poinapen, “I am trained as a physicist and I had no idea that I would get this ‘wow’ factor the first time I saw those images.”
The resolution shows detail to 10-20 microns (about 10 times smaller than the width of a human hair) and clearly shows the organs, reproductive system and other internal morphology.
“It’s a great example of how the interdisciplinary environment can benefit everyone’s research,” Poinapen said. “In our micro-CT lab, we know a lot about small-animal imaging – but knew very little about insects or our capacity to live-scan them until our biology collaborators came forward with this idea.”
For Konopka, it was a serendipitous side-project to her main area of research, which is the study of even smaller parasitic insects that lay eggs inside invasive insects that damage crops. “It’s fantastic to be able to have the research capability and flexibility, and be given the opportunity to expand your horizons. I’m not sure I could get that anywhere else.”
The team included Konopka and Poinapen; Robarts Research Institute imaging scientist David Holdsworth, principal investigator; and Biology professor Jeremy McNeil.
The bigger picture, said Holdsworth and McNeil, is the value of collaborative process and inter-disciplinary research.
“This is a great example of something that would not be possible in a typical biology lab nor in a typical medical research lab. We were able to draw together the strength of our diverse expertise and resources,” said Holdsworth, who is also a professor at the Schulich School of Medicine and Dentistry.
While his lab is primarily for medical research, his team has imaged everything from insects to meteorites: cross-disciplinary work that can only be done with funding support through partners such as Agriculture Canada and the Natural Sciences and Engineering Research Council of Canada.
“This is the kind of thing that we’re supposed to be doing at universities: cultivating the scientific curiosity that says ‘What would happen if …?’ and then accomplishing something spectacular and, in many ways, unexpected,” Holdsworth said.