Influence of carbon dioxide gas on German cockroach (Dictyoptera: Blattellidae) knockdown, recovery, movement and feeding

Carbon dioxide anaesthesia differentially affects the knockdown and recovery of cockroaches, depending on the strain and the length of time that the colony has been subjected to a CO2 regime. Adult males from two laboratory and two field-collected strains of German cockroaches, Blattella germanica, are knocked down within 7-45 s after exposure to CO2. After 5 min of CO2 exposure, presumptive recovery (i.e. the time for the cockroach to right itself after knockdown) for laboratory strains occurs significantly sooner than for field-collected strains. Control cockroaches, exposed to compressed air rather than CO2, exit harbourage cups rapidly (