Examination of a Biological Cryostat/Nanoliter Osmometer for Use in Determining the Freezing Point of Insect Hemolymph1

Abstract

Usefulness, convenience, and accuracy for measuring freezing-points of small amounts of arthropod fluid were examined with a biological cryostat/nanoliter osmometer. Sufficient fluid to make a measurement was obtained from aphids weighing as little as 0.21 mg, and no significance could be shown when comparing variations of measurements to size of the animal or to the amount of the available body fluid. Variations of measurements of standard NaCl solutions having known freezing-points ranging from —1.000 to —5.000C averaged ±0.055C SD. while arthropod hemolymph samples with freezing-points from —0.345 to —0.974C averaged ±0.048 C SD. The facile use of this apparatus is discussed, including use for possible determinations of freezing-points of tissue and secretions found in small arthropods.