Research & U: ‘Hoppers’

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By Aviva Hope Rutkin

What’s the difference between a small grasshopper and a big one?

This is one of the central questions of biology professor Scott Kirkton’s Homeostatic Orthopteran Performance, Physiology and Energetics Research—a.k.a, the HOPPER Lab.

During their lifespan of a few months, grasshoppers grow from about 10 mg to 2.5, the rough equivalent of a human infant gaining 1000 pounds in six weeks.

Kirkton and his thesis students attempt to understand how this change in body size affects the grasshoppers’ locomotion, muscle biochemistry and oxygen delivery.

They study videos of grasshoppers moving, perform biochemical assays to better understand the respiration process, and chase the insects around the room to see just how far they might jump.

Mary Donohue ‘12, a current thesis student in the HOPPER lab, studies X-ray videos of the grasshoppers breathing recorded by previous Union students at the Argonne National Laboratory in Illinois.

“[Insect projects] are a lot easier to do at a small school,” Kirkton explains. “It’s easier for undergrads to work on. They don’t need as much experience.”

Grasshoppers are by no means a new subject for Kirkton, who studied fruit flies, damsel flies, caterpillars and honeybees as a graduate student.

His lab at Union focuses on grasshoppers, a popular subject for respiration-minded entomologists.

Grasshoppers, like other insects, breathe through openings in their body wall. Air passes through a series of smaller and smaller tracheal tubes and diffuses to aerobically active cells.

About 250 million years ago, insects were far larger than they are now; the average cockroach, for example, was the size of a housecat. Some biologists believe that the big bugs were taking advantage of higher oxygen levels in the atmosphere. (Others argue that the size changes might be due to the current abundance of predators.)

This debate remains a focal question in Kirkton’s research. In past experiments, he has observed that young grasshoppers tend to rely more on anaerobic processes than older ones.

“Eventually down the road, I hope we’ll come up with a model as an invertebrate that we can use to answer some biomedically-related questions,” Kirkton says.

The grasshoppers live in cages in the basement of Science and Engineering, next door to Robert Olberg’s lizards and the Immunology class’s mice. Each year, a work-study student is tasked with feeding the grasshoppers. Dining Services provides the lab with about two cases of organic lettuce every week.

When he first came to Union several years ago, Kirkton had trouble keeping his colony alive, in part due to humidity and heating issues. Since then, Facilities has revamped the animal care rooms entirely.

Hundreds of them fly around the cages, but Kirkton picks them up and handles them with ease.

“Most seniors complain about their thesis, but I love it,” Donohue said.

 

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