Beetle battle

Gary Blomquist

Photo by Deidre Pike

Bark beetles are some of the most destructive pests in North America, says Gary Blomquist, a professor in the biochemistry department at the University of Nevada, Reno. The buggers destroy billions of linear feet of timber every year. UNR’s biochemistry department has been following the mating habits of these insects since 1993. Last week, Blomquist, a native of Michigan who received his Ph.D. from Montana State University, officially became the department’s chair.

So how do you explain your research to people at cocktail parties?

We work on insect pheromones. Do you know what pheromones are?

Something that has to do with sexual attraction?

Yes. For humans, this attraction is primarily physical—based on sight. For insects, it’s primarily chemical. Studying insect pheromones has great potential for insect control. If you can prevent or interfere with mating, you can stop reproduction.

So what kind of bug research do you do?

We have two major projects. We work with common houseflies, but probably of more interest is our work with bark beetles. A while back, we had an eight-year drought, from 1986 to 1994. During this time, at Tahoe, we had an outbreak of beetles. If you drive around Tahoe today, you’ll still see trees stripped by the beetles.

The beetles kill the trees?

If one beetle attacks the tree, the tree wins. So when a beetle arrives by itself at a tree, it attracts all the other beetles by sending out aggregation pheromones. Then the beetles stage a mass attack. Aggregation pheromones, which attract both male and female beetles, are the critical aspect. The beetles mate beneath the bark and form tunnels in the phloem to lay eggs. The beetles also carry blue-stained fungus. This gets into the xylem, the water system of the tree. The fungus attacks all the way to the heartwood.

That sounds like worse damage than that done by the logging industry.

Yes. Treehuggers should go after the beetles.

What have you learned?

When we started this work, it was thought that beetles took the turpentine compounds from pine trees—the chemical compounds that make a pine tree smell nice—and made these into pheromones. We found this not to be the case. A beetle makes its pheromones from scratch. … We’ve looked at biosynthetic pathways and pheromone regulation. It turns out that the same enzyme that regulates cholesterol in humans regulates pheromones in beetles. … Beetles are productive insects. A beetle can produce over 5 percent of its body weight in pheromones a week. An American cockroach only produces a billionth of an ounce of pheromone a month. A beetle the size of a grain of rice can produce two micrograms a week. Where other insects have glands that produce pheromones, a beetle produces it in its midgut. They poop out their pheromones, literally.

Do you have beetles here at UNR?

Yes, we collect them near Donner and Spooner lakes. We harvest about 10,000 to 20,000 a year and do our experiments on them.