Note on Specific Gravity of Haemolymph ofMelanoplus bivittatus(Say) andMelanoplus mexicanus(Sauss.) (Orthoptera: Locustidae)

Abstract

It was necessary to know the specific gravity of the haemolymph, or blood, of grasshoppers for certain investigations on insect immunity, This information is not given in reviews on the physical properties of insect haemolymph (Rapp, 1947; Buck, 1953). Determinations of specific gravity were made by the technique developed by Lowry and Hunter (1945) and used on insects by Baldwin and House (1352). Nine males and 11 females ofMelanoplus bivittatus(Say) and 11 males and nine females ofMelanoplus mexicanus(Sauss.) were used after they had fed in the laboratory for three days on lettuce and dry dietary components. The mean specific gravity and the standard deviation forM. bivittatuswas 1.0271 ± .0043, 1.0262 ± .0046, for the male and 1.0281 ± .0039 for the female; forM. mexicanus, 1.0261 ± .0023, 1.0257 ±.0021, and 1.0264 ± .0025, respectively.