Acetylcholinesterase activity in forager honey bees of Nepal

Acetylcholinesterase (AChE) is a promising enzyme and a biomarker to monitor the physiological status of honey bees. To gain a basic understanding of AChE in bees, we measured AChE activity in the head tissue of forager honey bees belonging to Apis cerana, Apis mellifera, and Apis dorsata collected from five districts of Nepal during pre-winter and winter seasons. We estimated AChE-tissue activity (μmol/min/g head tissue) and AChE-specific activity (μmol/min/mg protein) using Ellman assay kit and protein concentration (mg/g head tissue) using Lowry assay method. A significant increase in all three parameters was observed in winter A. cerana and varied between species indicating differences in physiological resistance and responses to various environmental changes between native (A. cerana and A. dorsata) and non-native (A. mellifera) bees. Overall, AChE-tissue and specific activities were positively correlated and, as expected, AChE-specific activity was negatively correlated with the protein concentration.