ACTIVITY OF PHOSPHATASES AND ESTERASES IN THE APHID, ACYRTHOSIPHON-PISUM (HEMIPTERA, STERNORRHYNCHA, APHIDIDAE), AND IN THE GUT WALL OF GALLERIA-MELLONELLA (LEPIDOPTERA, PYRALIDAE) LARVAE AND PUPAE

The activity and isozyme patterns of esterases and phosphatases which hydrolyse ecdysteroid conjugates were studied in whole body extracts o f Acyrthosiphon pisum (Harris) and in midgut wall extracts of Galleria mellonella (L.). The activity of esterases was almost ten times highe r than that of phosphatases (expressed in mu M liberated para-nitrophe nol/min/mg protein) and seemed to decline with insect age. Cholinester ase sensitive to eserin comprised 14% of total esterase activity in th e nymphs of A. pisum, while in other samples it was negligible. Activi ty of acid phosphatases in the aphid samples was twice as high as that of alkaline phosphatases, while a reverse 3 : 1 ratio was found in th e wax moth. The alkaline phosphatases revealed higher sensitivity to f luoride than the acid phosphatases. Esterases were more variable in th eir isozyme patterns during development than the phosphatases. A possi ble mechanism of ecdysteroid mobilization from their conjugates and th e role of hydrolyzing enzymes in these processes is discussed.