Do you feel crankier first thing in the morning or after a hard day’s work? Maybe even a little more vulnerable? We all do. Well, as it turns out, insects – including the kind that devour your plants or create other headaches – feel the same way. As with humans, it’s a consequence of their natural circadian rhythms, or biological clocks. And according to researchers at Oregon State University, there may be ways to use this information against these problem pests. How? By targeting pesticide application to certain times to day. Louisa Hooven, a postdoctoral fellow in the OSU Department of Zoology and lead author on the study, summarized the findings:

“We found that it took triple the dose of one pesticide to have the same lethal effect on fruit flies at the time of day their defenses were strongest, compared to when they were weakest. A different pesticide took twice the dose. This makes it pretty clear that the time of day of an exposure to a pesticide can make a huge difference in its effectiveness.”

According to OSU zoology professor Jadwiga Giebultowicz, further research must be done to develop practical applications for this new discovery that can be used in agriculture:

“We will need to test specific insects against specific pesticides, and we will probably find differences in time of maximum effectiveness for various pest-pesticide configurations. In some cases we may be able to greatly improve the effectiveness of pesticides or allow the use of reduced doses.”

The study was supported by the U.S. Department of Agriculture, National Institutes of Health and National Science Foundation. The findings were published in PLoS ONE, a professional journal. (Fruit fly photo ©2005, André Karwath)