Effect of age on insecticide susceptibility and enzymatic activities of three detoxification enzymes and one invertase in honey bee workers (Apis mellifera)

Authors: Zhu, Yu Cheng; Caren, Joel; Reddy, Gadi V.P.; LI, WENHONG - Guizhou Academy Of Agricultural Sciences; Yao, Jianxiu

Submitted to: Comparative Biochemistry and Physiology Part C: Toxicology & Pharmacology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/3/2020
Publication Date: 8/7/2020
Citation: Zhu, Y., Caren, J.R., Reddy, G.V., Li, W., Yao, J. 2020. Effect of age on insecticide susceptibility and enzymatic activities of three detoxification enzymes and one invertase in honey bee workers (Apis mellifera). Comparative Biochemistry and Physiology Part C: Toxicology & Pharmacology. 238(2020). https://doi.org/10.1016/j.cbpc.2020.108844.
DOI: https://doi.org/10.1016/j.cbpc.2020.108844

Interpretive Summary: Honey bee, a significant contributor of honey production and pollination, has been concerned over the toxicity of pesticides, one of the major risk factors on population decline. However, age effects of honey bees on pesticide susceptibility have been largely ignored and many researchers use bees of unknown age for assessing the risk of pesticides. Honey bee workers are known to go through physiological and behavioral changes in order to differentiate different phenotypes to perform specific duties over their natural lifetime of 6 weeks or longer. In this study, we provide multi-parameter evidences of unignorable age effects of honey bee workers and suggest using a standard bee age to produce reliable and comparable data when assessing variable and realistic situations of in-hive and field exposures to pesticides. Using honey bee workers aged 4 days to 42 days old, we examined susceptibility of the bees to five different insecticides from five different classes and measured enzymatic activities of three major detoxification enzymes and an invertase involved in honey production. Results showed gradual increase of natural mortality and decrease of soluble protein content in bees over the age span from 4 days to 42 days. Significant increases of mortality after separate treatments of five different insecticides confirmed drastic age effects of bees over the assessed age span. As they aged, honey bees also showed a gradual increase of cytochrome P450 oxidase activity while still maintaining constant levels of two other detoxification enzymes (esterase and glutathione S-transferase) and an invertase responsible for honey production.

Technical Abstract: Honey bee, a significant contributor of honey production and pollination, has been concerned over the toxicity of pesticides, one of the major risk factors on population decline. However, age effects of honey bees on pesticide susceptibility have been largely ignored and many researchers use bees of unknown age for assessing the risk of pesticides. Honey bee workers are known to go through physiological and behavioral changes in order to differentiate different phenotypes to perform specific duties over their natural lifetime of 6 weeks or longer. In this study, we provide multi-parameter evidences of unignorable age effects of honey bee workers and suggest using a standard bee age to produce reliable and comparable data when assessing variable and realistic situations of in-hive and field exposures to pesticides. Using honey bee workers aged 4 days to 42 days old, we examined susceptibility of the bees to five different insecticides from five different classes and measured enzymatic activities of three major detoxification enzymes and an invertase involved in honey production. Results showed gradual increase of natural mortality and decrease of soluble protein content in bees over the age span from 4 days to 42 days. Significant increases of mortality after separate treatments of five different insecticides confirmed drastic age effects of bees over the assessed age span. As they aged, honey bees also showed a gradual increase of cytochrome P450 oxidase activity while still maintaining constant levels of two other detoxification enzymes (esterase and glutathione S-transferase) and an invertase responsible for honey production.