Acetylcholinesterase1 as a potential biomarker for detecting stress conditions in honey bee workers

There are two different types of acetylcholinesterase (AChE1 and AChE2) in the western honeybee as in most of insects. It is suggested that soluble AmAChE1 might be related with a stress response as judged from its elevated expression level in honey bee workers when brood rearing was suppressed. In this study, to ensure the nature of AmAChE1 responding to stress factors, the expression patterns of AmAChE1 following heat shock, brood rearing suppression and chemical treatments (Imidacloprid and fluvalinate) were investigated. Also, several heat shock protein (hsp) genes (hsp10, hsp60, hsp70 and hsp90) known as general stress markers were tested as positive references. Heat shock induced expression of every tested hsp along with AmAChE1. In brood rearing-suppressed worker bees, 7 days old bees showed much higher expression level of AmAChE1 and hsp90 compared to control honey bees. However, treatment of imidacloprid and fluvalinate did not induce any apparent overexpression of these genes. These results confirm that both HSP and AmAChE1 genes generally respond to temperature and brood rearing suppression and further suggest that AmAChE1 can serve as a potential biomarker along with hsps for the detection of stress in honey bee colonies.