The activity of carboxylesterase produced by larvae of Stenopsyche marmorata NAVAS (Trichoptera : Stenopsychidae) in the field

Abstract

The larvae of Stenopsyche marmorata NAVAS (Trichoptera : Stenopsychidae) were collected from the Kita-asakawa River, Hachioji, Tokyo in summer and winter. Carboxylesterase (CE) activities of the larvae were determined to estimate their internal pupation activity. The larvae were frozen and ground in liquid nitrogen and suspended in buffer solution individually. The samples were centrifuged and the supernatant was collected to monitor the CE activity. The activities were determined by measuring the amountof p-nitrophenol from p-nitrophenyl acetate substrates. The activities were constant during an initial stage of the last instar, but they increased in a later period of the stage. Regarding the individuals showing about the same CE activities, the range of larval weight in the overwintering generation was larger than that in the non-overwintering one. This corresponds with the phenomenon that the body size of S. marmorata at maturation is bigger in overwintering generations than in non-wintering ones.