Pyrethroid residue dynamics in insects depends on the circadian clock.

Many factors may affect pesticide effectiveness against pests. One of the factors that should be considered is circadian rhythmicity. In this study, we evaluated daily variations in pyrethroid susceptibility in the house cricket, Acheta domesticus L. Crickets were exposed to a standard dose of ß-cyfluthrin at different times of a day, and pesticide residue levels were evaluated using gas chromatography. Results demonstrate that the time of pyrethroid disappearance is correlated with the circadian clock, with the highest decomposition rate at night. Furthermore, crickets also showed the highest resistance to the insecticide at night, expressed as a high survival rate. Moreover, ß-cyfluthrin induced significant changes in thermal preferences of intoxicated crickets. This is the first report showing that pyrethroid residue levels in the crickets' body depend on its circadian clock.