Abstract
Studies were carried out on the activity of esterase enzymes in three castes of the termite P. hybostoma Desneux and the inhibition of Cholinesterase in workers by some pesticides. Workers showed the highest level of Acetylcholinesterase (AchE) followed by winged forms, and levels of this enzyme in both were much higher than those of either Cholinesterase (ChE) or Aliesterase (AliE) of the same caste. ChE was however more active in soldiers than AchE or AliE. The carbamate compound Sevin proved to be more effective in inhibiting ChE in workers than the organophosphate, Sumithion or the pyrethroid, Permethrin. The chlorinated hydrocarbons, Gamma BHC and Chlordane were the least effective.