When autumn temperatures fall toward the freezing point, wise motorists put antifreeze in their radiators. Many wise insects do much the same thing, reports Biochemist Fred Smith of the University of Minnesota. What's more, their antifreeze is glycerol (glycerin), a chemical that closely resembles the ethylene glycol that is the basis for many antifreeze brands.
Working with Dr. Peter Dubach, Douglas Pratt and C. M. Stewart, Professor Smith was studying the hibernating larvae of woodboring beetles (Melandrya striata), trying to isolate the enzymes that digest the cellulose on which the insects live. But when he ground up the larvae and analyzed the juice, he was surprised to find a considerable glycerol content. Since the active summer larvae do not contain glycerol, he guessed that the larvae possessed a mechanism that reacted to cold by producing glycerol to keep their tissues from freezing in the Minnesota winters.
To check his theory. Professor Smith experimented on black carpenter ants, which are easy to collect in quantity. Hibernating adult ants proved to have as much as 10% glycerol in their bodies, but when the ants were gradually warmed up and became active, all of it disappeared. Chilling the ants for a few days at a temperature just above the freezing point restored the glycerol again. Ants of the same species found in warmer Maryland had no glycerol in them. But when taken to Minnesota, they did as Minnesota ants do, secreting their personal antifreeze against the cold.