STUDIES ON EFFECTS OF THERMAL CONDITIONING IN TWO SPECIES OF SAWFLY LARVAE

Abstract

Conditioning larvae of the sawflies Neodiprion lecontei (Fitch) and Neodiprion sertifer (Geoff.) at moderately high temperatures increased the thermal tolerance of both species. In both species increased resistance was accompanied by a significant increase in specific gravity of the haemolymph. The osmotic pressure of the haemolymph of N. sertifer was increased by about 20%. These effects may be significant in the mechanism whereby increased tolerance to high temperatures is achieved in the living insect. The normal pH of the haemolymph of N. sertifer larvae was not altered by heat treatment, indicating that its buffering capacity was not overcome.