Low temperature and insect activity

Abstract

The "chill-coma temp." is the temp. at which the insect is immobilized by the cold. Insects used in the expts. were Blatta orientalis, Cimex lectularius, Rhodnius prolixus, Lucilia sericata, Calliphora erythro-cephala and Glossina palpalis. Adjustment to the chill-coma temp. usually occurred within 20 hrs. When insects were cooled below the chill-coma temp. and then warmed, recovery was slower the greater the cooling. During chill-coma, insects from high temps. did not become adjusted to the low temp. Insects of the same sp. from warm conditions were less cold-hardy and more easily killed by exposure to conditions below zero, than those from cool. The threshold temp. for spontaneous movements was usually several degrees higher than that at which movements were possible. Within the zone of normal activity, when an insect was transferred from one temp. to another, its rate of movement quickly altered to that characteristic of the new temp.; it was only outside the zone of normal activity that the rate of movement was greatly affected by the previous conditions. The rate of movement may be controlled directly by the rate of metabolism.