EFFECT OF SOME ORGANOPHOSPHATE INSECTICIDES ON ACETYLCHOLINESTERASE OF ADULT COCCINELLA-SEPTEMPUNCTATA (COCCINELLIDAE)

The in vitro enzyme activity of head homogenates of Coccinella septemp unctata from different habitats (wheat, barley, rye and set-aside fiel ds in Belgium and Hungary) and the effect of in vivo surface contact t reatments with organophosphorous active ingredients on the same specie s were investigated. The in vitro studies indicated that the acetylcho linesterase (AChE) of C. septempunctata was less sensitive to inhibiti on by paraoxon than by malaoxon in the case of each population. The di fferences found between parathion and malathion treatments in in vivo testing were not significant. The inhibition process of paraoxon sugge sts that the seven-spot ladybird may have at least two AChEs respondin g differently for the paraoxon inhibition.