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Exposure of honey bees (Apis mellifera L.) to Organophosphorous insecticides in Saskatchewan, Canada
... Declines in populations of honey bees are of global concern to agriculture, because each year the European honey bee (Apis mellifera) adds approximately $40 billion to the world economy (Fairbrother et al. 2014; Klein et al., 2007). Although causes of increased rates of failure of colonies are still unclear, results of some studies have suggested that extensive use of insecticides might be a responsible co-factor for failures of colonies (Al Naggar, Codling, et al., 2015a, Al Naggar, Vogt, et al., 2015b Mullin et al., 2010). The major cause of colony loss is, however, thought to be due to parasitism by the mite Varroa destructor and associated pathogens (Martin et al., 2012, Ryabov et al. 2014 ). ...
... Declines in populations of honey bees are of global concern to agriculture, because each year the European honey bee (Apis mellifera) adds approximately $40 billion to the world economy (Fairbrother et al. 2014; Klein et al., 2007). Although causes of increased rates of failure of colonies are still unclear, results of some studies have suggested that extensive use of insecticides might be a responsible co-factor for failures of colonies (Al Naggar, Codling, et al., 2015a, Al Naggar, Vogt, et al., 2015b Mullin et al., 2010). The major cause of colony loss is, however, thought to be due to parasitism by the mite Varroa destructor and associated pathogens (Martin et al., 2012, Ryabov et al. 2014 ). ...
Efficacies of two miticides, Apivar® and Thymovar®, were evaluated as a fall treatment against V. destructor. The effect of treatment with miticides was further evaluated by monitoring both viral load and rate of indoor overwintering survival of colonies of European honey bees (Apis mellifera L.) in the vicinity of Saskatoon, Saskatchewan, Canada. Forty-five colonies were randomly assigned to three treatment groups with 15 hives per group: Group 1; 2 strips of Thymovar® (thymol); Group 2; 2 strips of Apivar® (Amitraz); and Group 3; no treatment (control). Significant decreases in the rates of colony infestation (Mites per hundred bees, MPHB) by V. destructor were observed (p < 0.05) between colonies of bees treated with Apivar® in October 2013 when compared to control colonies. Efficacy of Apivar® and Thymovar® against V. destructor after treatment for 22 days were 76.5 and 26.7%, respectively. After 22 days, concentrations of the two miticides in bees were 15.4 ng amitraz/g wet mass (wm) and 64,800 ng thymol/g wm. There were no significant differences (p > 0.05) in the percentage of colonies infected by deformed wing virus (DWV) and Israeli acute paralysis virus (IAPV) either before or after treatment with Apivar® or Thymovar® in October 2013 and 7 months post treatment in April 2014. Only the Apivar® treatment group showed IAPV infections in April 2014. The group treated with Apivar® exhibited a better overwintering rate of survival (93%), than hives treated with Thymovar® (67%). These results suggest volatile miticides like Thymovar® should be avoided in geographical areas with colder fall temperatures.
... The 128,000 hives in Saskatchewan are vital to the economy of the province because they provide significant revenue for beekeepers through production of honey and benefits of pollination for many crops. In Saskatchewan, approximately 11.3 Â 10 6 kg of honey is produced annually and 23% of the honey sold in Canada (Al Naggar et al., 2015b ). Due to importance of bees in Saskatchewan's farming industry and concerns over loss, a study of multiple colonies, was conducted to investigate whether or not NIs could be detected in bees and hive products. ...
... The 128,000 hives in Saskatchewan are vital to the economy of the province because they provide significant revenue for beekeepers through production of honey and benefits of pollination for many crops. In Saskatchewan, approximately 11.3 Â 10 6 kg of honey is produced annually and 23% of the honey sold in Canada (Al Naggar et al., 2015b). Due to importance of bees in Saskatchewan's farming industry and concerns over loss, a study of multiple colonies, was conducted to investigate whether or not NIs could be detected in bees and hive products. ...
BACKGROUND
Recently, cyantraniliprole (CYA) and sulfoxaflor (SUL) have been considered as alternatives to neonicotinoid insecticides. In this study, we evaluated the acute and chronic toxicities of CYA and SUL on honey bee (Apis mellifera L.) larvae reared in vitro.
RESULTS
In the acute toxicity test, the following test doses were used to determine the median lethal dose (LD50): CYA 0.007, 0.014, 0.028, 0.056 and 0.112 μg larva⁻¹; SUL 2.5, 5, 10, 20 and 40 μg larva⁻¹. In the chronic toxicity test, the following test doses were used to determine the LD50: CYA 0.00512, 0.0128, 0.032, 0.08 and 0.2 μg larva⁻¹; SUL 0.0625, 0.125, 0.25, 0.5 and 1.0 μg larva⁻¹. The acute LD50 values of CYA and SUL were 0.047 and 11.404 μg larva⁻¹, respectively. Larvae acutely exposed to SUL had significantly lower body weight than controls, but those exposed to CYA showed no difference. The no observed adverse effect level (NOAEL) and LD50 values of the chronic toxicity tests for each insecticide were 0.00512 and 0.064 μg larva⁻¹ for CYA, and 0.0625 μg larva⁻¹ and 0.212 μg larva⁻¹ for SUL, respectively. Larvae chronically exposed to SUL emerged as bees with deformed wings, reaching adult deformation rates of over 50%; however, CYA had no effect on adult deformation.
CONCLUSION
Exposure to CYA increased larval mortality but did not cause any adult deformation, whereas SUL exposure increased pupal mortality and caused wing deformation in newly emerged bees. Our study may be useful for the assessment of pesticide toxicity by providing valuable findings on the effects of these insecticides on honey bee larvae. © 2022 Society of Chemical Industry.
BACKGROUND
The effects of chronic exposure to two neonicotinoids (clothianidin and imidacloprid) and two organophosphates (chlorpyrifos and dimethoate) on survival, developmental rate and larval weight of honey bee larvae reared in vitro were determined. Diets containing chemicals were fed to larvae with the range of concentrations for each compound based on published acute toxicity experiments and residues found in pollen and nectar, both components of the larval diet.
RESULTS
Four concentrations of each compound and controls were tested: chlorpyrifos: 0.5, 0.8, 1.2, 8 mg/L; clothianidin: 0.1, 0.4, 2, 10 mg L⁻¹; dimethoate: 0.02, 1, 6, 45 mg L⁻¹; imidacloprid: 0.4, 2, 4, 10 mg L⁻¹; positive control: dimethoate (45 mg L⁻¹); solvent control: acetone or methanol; and negative control. A significant decrease in survival, relative to the solvent control, occurred in the 0.8, 1.2 and 8 mg L⁻¹ chlorpyrifos, 0.4, 2 and 10 mg L⁻¹ clothianidin, and 45 mg L⁻¹ dimethoate diets, but not the imidacloprid diets.
CONCLUSION
The treatment of larval diets with clothianidin, dimethoate and imidacloprid did not affect survival, developmental rate, or weight of immature honey bees; however, treatment with chlorpyrifos did. Overall, our results are valuable for evaluating the chronic toxicity of these pesticides to developing honey bees. © 2018 Society of Chemical Industry
We assessed whether exposure to environmentally-relevant mixtures of four organophosphorus insecticides (OPs) exerted adverse effects on honey bees. Adult and worker bees were orally exposed for five days under laboratory conditions to mixtures of four insecticides, diazinon, malathion, profenofos and chlorpyrifos at two concentrations. Concentration in the mixtures tested were equivalent to the median and 95th centile concentrations of the OPs in honey, as reported in the literature. Effects on survival, behavior, activity of acetylcholinesterase (AChE), and expression of genes important in detoxification of xenobiotics and immune response were examined. Survival of worker bees was not affected by exposure to median or 95th centile concentrations of the OPs. Activity of AChE was significantly greater in worker bees exposed to the 95th centile concentration mixture of OPs compared to the median concentration mixture. Expression of genes involved in detoxification of xenobiotics was not affected by treatment , but the abundance of transcripts of the antimicrobial peptide hymenoptaecin was significantly greater in worker honey bees exposed to the median concentration mixture. Results suggest that short-term exposure to environmentally relevant concentrations of a mixture of OPs do not adversely affect worker honey bees.
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