Influences of acephate and mixtures with other commonly used pesticides on honey bee (Apis mellifera) survival and detoxification enzyme activities

Authors: YAO, JIANXIU - Kansas State University; Zhu, Yu Cheng; Adamczyk, John; Luttrell, Randall

Submitted to: Comparative Biochemistry and Physiology Part C: Toxicology & Pharmacology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/16/2018
Publication Date: 4/3/2018
Publication URL: http://handle.nal.usda.gov/10113/5934976
Citation: Yao, J., Zhu, Y., Adamczyk Jr, J.J., Luttrell, R.G. 2018. Influences of acephate and mixtures with other commonly used pesticides on honey bee (Apis mellifera) survival and detoxification enzyme activities. Comparative Biochemistry and Physiology Part C: Toxicology & Pharmacology. 209:9-17. https://doi.org/10.1016/j.cbpc.2018.03.005.

Interpretive Summary: Acephate is frequently used to control piercing/sucking insects in field crops in USA, then may pose a risk to honey bees. In this study, toxicities of acephate were examined in honey bees through feeding treatments with median-lethal (LC50: 6.97 mg/L) and sublethal (residue level in pollen: 0.168 mg/L) concentrations. Acephate-intoxicated bees started to show significantly suppressed esterase activity at 6 h, while the activities of acetylcholinesterase (AChE) and cytochrome P450 monooxygenases (P450s) were not altered until 48 h of feeding. It took 72 h to show significantly suppressed glutathione S-transferase (GST) activity in acephate-treated bees. Approximately 79.9% esterase, 20.4% GST, and 29.4% AChE activities were significantly suppressed by acephate, while the P450 activity was elevated by 20% after 48-h feeding. Workers treated with acephate at residue concentration did not significantly increase bee mortality, but body weight and esterase activity were significantly reduced. Similarly, workers treated with binary mixtures of acephate with six formulated pesticides showed consistently lower body weight and esterase activity. Clothianidin, '-cyhalothrin, oxamyl, tetraconazole, and chlorpyrifos may interact with acephate synergistically to reduce body weight in treated bees. Even though feeding on sublethal acephate did not kill honey bees directly, chronic toxicity to honey bee was noticeable (body weight loss and esterase suppression) and its potential risk of synergistic interactions with other formulated pesticides should not be ignored.

Technical Abstract: Acephate is frequently used to control piercing/sucking insects in field crops in USA, then may pose a risk to honey bees. In this study, toxicities of acephate were examined in honey bees through feeding treatments with median-lethal (LC50: 6.97 mg/L) and sublethal (residue level in pollen: 0.168 mg/L) concentrations. Acephate-intoxicated bees started to show significantly suppressed esterase activity at 6 h, while the activities of acetylcholinesterase (AChE) and cytochrome P450 monooxygenases (P450s) were not altered until 48 h of feeding. It took 72 h to show significantly suppressed glutathione S-transferase (GST) activity in acephate-treated bees. Approximately 79.9% esterase, 20.4% GST, and 29.4% AChE activities were significantly suppressed by acephate, while the P450 activity was elevated by 20% after 48-h feeding. Workers treated with acephate at residue concentration did not significantly increase bee mortality, but body weight and esterase activity were significantly reduced. Similarly, workers treated with binary mixtures of acephate with six formulated pesticides showed consistently lower body weight and esterase activity. Clothianidin, '-cyhalothrin, oxamyl, tetraconazole, and chlorpyrifos may interact with acephate synergistically to reduce body weight in treated bees. Even though feeding on sublethal acephate did not kill honey bees directly, chronic toxicity to honey bee was noticeable (body weight loss and esterase suppression) and its potential risk of synergistic interactions with other formulated pesticides should not be ignored.