Extreme Survival—Insect Style!

The sugar beet root maggot, Tetanops myopaeformis, is the "alpha" pest of insects that attack sugar beets. This is especially true in the Red River Valley regions of North Dakota and Minnesota, where about 51 percent of the total U.S. sugar beet crop is grown.

So why are Agricultural Research Service (ARS) scientists and collaborators in Fargo, N.D., excited about discovering that Tetanops can survive five years of refrigerated storage—and even months in water?

The answer has to do with the saying, "Know thine enemy." In order to develop novel ways of fighting Tetanops or other insect pests, scientists must rear large colonies of them in the lab for detailed study. This can cost thousands, if not millions, of dollars annually. Being able to keep the insects in cold storage until needed could help cut the cost and save time, notes George Yocum, a physiologist in the ARS Insect Genetics and Biochemistry Research Unit at Fargo.

Yocum and North Dakota State University colleagues Mark Boetel and Anitha Chirumamilla are studying cold storage of Tetanops for another reason: to avoid inbreeding that can make lab-reared colonies genetically different from targeted populations in beet fields.

In studies, the researchers compared the respiration, lipid use and gene activity of dormant Tetanops larvae collected in the field to those stored in the lab at 41 to 45 degrees Fahrenheit for up to five years. Of those, 54 percent developed into adult flies when warmed up. The larvae also survived submersion in tap water at room temperature for three months. Yocum suspects Tetanops' capacity for survival is an evolutionary adaptation to flooding and freezing in the Red River Valley region.

Yocum's team is focusing attention on hibernation-like mechanisms that the insect may use, including metabolism regulation and cell-protecting antifreeze that's not been observed in other insects.

Potentially, Tetanops could serve as a model organism for cold-storage applications in other fields, such as improved quarantine techniques and biomedical efforts to extend the storage and transport of human organs for transplant.

ARS is the U.S. Department of Agriculture's chief scientific research agency.