Comparative examination on synergistic toxicities of chlorpyrifos, acephate or tetraconazole mixed with pyrethroid insecticides to honey bees (Apis mellifera)

Authors: WANG, YANHUA - Zhejiang Academy Of Agricultural Sciences; Zhu, Yu Cheng

Submitted to: Environmental Science and Pollution Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/28/2019
Publication Date: 12/27/2019
Citation: Wang, Y., Zhu, Y. 2019. Comparative examination on synergistic toxicities of chlorpyrifos, acephate or tetraconazole mixed with pyrethroid insecticides to honey bees (Apis mellifera). Environmental Science and Pollution Research. 27:6971-6980. https://doi.org/10.1007/s11356-019-07214-3.
DOI: https://doi.org/10.1007/s11356-019-07214-3

Interpretive Summary: Potential synergistic toxicity of pesticide mixtures has increasingly become a concern to honey bee health. The toxicities of individual and mixture of chlorpyrifos (CHL), acephate (ACE), or tetraconazole (TET) with nine pyrethroid insecticides to honey bees were evaluated in this study to reveal any aggregated interaction between pesticides. Results from toxicity test of individual pesticides indicated that organophosphate insecticides CHL and ACE had higher toxicities to honey bees compared with nine pyrethroids. Moreover, different pyrethroids exhibited considerable variation in toxicity with LC50 (Lethal concentration which causes 50% mortality in test organism) values ranging from 10.05 (8.60-11.69) to 1,125 (922.4-1,442) mg a.i. L-1 (a.i.: active ingredient of the chemical) after exposure for 7 days. Among the twelve examined pesticides, a relatively low toxicity to A. mellifera was detected from the fungicide TET. All the binary mixtures of ACE or TET in combination with pyrethroids exhibited synergistic effects. However, TET in combination with pyrethroids showed greater synergistic toxicity to A. mellifera than ACE in combination with pyrethroids. Approximately 50% binary mixtures of CHL in combination with pyrethroids also showed synergistic responses in honey bees. In particular, CHL, ACE or TET in combination with either lambda-cyhalothrin (LCY) or bifenthrin (BIF) showed the strongest synergy to A. mellifera, followed by CHL, ACE or TET in combination with either zeta-cypermethrin (ZCY) or cypermethrin (CYP). The findings indicated that the co-exposure of various pesticides in natural settings might lead to severe injury to crop pollinators. Therefore, mixing pesticides should be applied carefully in order to minimize negative effects on honey bees while maintain effective management against crop pests.

Technical Abstract: BACKGROUND: Potential synergistic toxicity of pesticide mixtures has increasingly become a concern to honey bee health. The toxicities of individual and mixture of chlorpyrifos (CHL), acephate (ACE), or tetraconazole (TET) with nine pyrethroid insecticides to honey bees were evaluated in this study to reveal any aggregated interaction between pesticides. RESULTS: Results from toxicity test of individual pesticides indicated that organophosphate insecticides CHL and ACE had higher toxicities to honey bees compared with nine pyrethroids. Moreover, different pyrethroids exhibited considerable variation in toxicity with LC50 values ranging from 10.05 (8.60-11.69) to 1,125 (922.4-1,442) mg a.i. L-1 after exposure for 7 days. Among the twelve examined pesticides, a relatively low toxicity to A. mellifera was detected from the fungicide TET. All the binary mixtures of ACE or TET in combination with pyrethroids exhibited synergistic effects. However, TET in combination with pyrethroids showed greater synergistic toxicity to A. mellifera than ACE in combination with pyrethroids. Approximately 50% binary mixtures of CHL in combination with pyrethroids also showed synergistic responses in honey bees. In particular, CHL, ACE or TET in combination with either lambda-cyhalothrin (LCY) or bifenthrin (BIF) showed the strongest synergy to A. mellifera, followed by CHL, ACE or TET in combination with either zeta-cypermethrin (ZCY) or cypermethrin (CYP). CONCLUSIONS: The findings indicated that the co-exposure of various pesticides in natural settings might lead to severe injury to crop pollinators. Therefore, mixing pesticides should be applied carefully in order to minimize negative effects on honey bees while maintain effective management against crop pests.