Pesticide Chronotoxicity to Insects and Mites: An Overview

Chronotoxicity may be defined as the changes in an organism's sensitivity to toxicants in relation to time. A review of research papers reveals numerous examples of a sensitive period to insecticides and miticides during a 24-hour cycle, or a circadian rhythm of sensitivity. In rare instances bimodal or tri-modal rhythms of susceptibility have been determined. The circadian rhythms of insect sensitivity to toxicants have been related to rhythmic biochemical processes. Thus, behavioral and physiological rhythms might be considered as marker rhythms for the rhythmic patterns of sensitivity to toxicants. However, the circadian peaks of sensitivity may not always be correlated with activity and metabolism. The practical application of the circadian sensitivity to toxins has had limited study and perhaps deserves greater attention.