RESUMO
Neonicotinoid insecticides have been used in a wide range of crops through seed treatment, soil and foliar applications and a large database exists on both their lethal and sub-lethal effects on honey bees under controlled laboratory conditions. However, colony-level studies on the effects of neonicotinoids in field studies are limited, primarily due to their complexity and the resources required. This paper reports the combined results of two large-scale colony-feeding studies, each with 6â¯weeks of continuous dosing of 12 colonies per treatment (24 control) to 12.5, 25, 37.5, 50 or 100â¯ngâ¯thiamethoxam/g sucrose solution. Exposure continued beyond dosing with residues present in stored nectar and bee-bread. The studies were conducted in an area with limited alternative forage and colonies were required to forage for pollen and additional nectar The studies provide colony-level endpoints: significant effects (reductions in bees, brood) were observed after exposure to the two highest dose rates, colony loss occurred at the highest dose rate, but colonies were able to recover (2-3 brood cycles after the end of dosing) after dosing with 50â¯ngâ¯thiamethoxam/g sucrose. No significant colony-level effects were observed at lower dose rates. The data reported here support the conclusions of previous colony-level crop-based field studies with thiamethoxam, in which residues in pollen and nectar were an order of magnitude below the colony-level NOEC of 37.5â¯ngâ¯thiamethoxam/g sucrose. The feeding study data are also compared to the outcomes of regulatory Tier 1 risk assessments conducted using guidance provided by the USA, Canada, Brazil and the EU regulatory authorities. We propose an adaptation of the European chronic adult bee risk assessment that takes into account the full dataset generated in laboratory studies while still providing an order of magnitude of safety compared with the colony feeding study NOEC.
Assuntos
Abelhas/efeitos dos fármacos , Exposição Ambiental/efeitos adversos , Inseticidas/toxicidade , Tiametoxam/toxicidade , Ração Animal/análise , Animais , Abelhas/crescimento & desenvolvimento , Abelhas/metabolismo , Relação Dose-Resposta a Droga , Exposição Ambiental/análise , Mel/análise , Inseticidas/administração & dosagem , Nível de Efeito Adverso não Observado , Néctar de Plantas/química , Pólen/química , Própole/biossíntese , Medição de Risco , Estações do Ano , Sacarose/química , Tiametoxam/administração & dosagem , Fatores de TempoRESUMO
A semifield study to assess the effects of iprodione on honeybees at label use rates was conducted on a bloom mustard crop. The present study followed the Organisation for Economic Co-operation and Development guideline 75 tunnel test and consisted of 3 groups: the iprodione-treated group, the untreated control group, and the toxic reference item group. In addition to the tunnels used for biological assessments, a tunnel was set up in the treatment and control groups to determine the level of residues in flowers, nectar, and pollen. The major endpoints to assess the effects of the application of iprodione were mortality, flight intensity, behavior, condition of the colonies, and development of the brood. Residue analysis showed that honeybees were exposed to significant residues of iprodione. However, no adverse effects were observed on overall mortality, flight intensity, behavior, or brood development of honeybees compared to control. It is concluded that iprodione does not adversely affect the health of honeybees when applied in agriculture at commercially relevant rates in a worst-case exposure scenario. Environ Toxicol Chem 2018;37:3086-3094. © 2018 SETAC.
Assuntos
Aminoimidazol Carboxamida/análogos & derivados , Abelhas/crescimento & desenvolvimento , Comportamento Animal/efeitos dos fármacos , Flores/fisiologia , Fungicidas Industriais/toxicidade , Hidantoínas/toxicidade , Mostardeira/fisiologia , Folhas de Planta/efeitos dos fármacos , Aminoimidazol Carboxamida/toxicidade , Animais , Abelhas/efeitos dos fármacos , Voo Animal/efeitos dos fármacos , Mostardeira/efeitos dos fármacos , Néctar de Plantas/química , Pólen/química , Análise de SobrevidaRESUMO
Neonicotinoid insecticides have been used globally on a wide range of crops through seed treatment as well as soil and foliar applications and have been increasingly studied in relation to the potential risk to bees because of their detection in pollen and nectar of bee-attractive crops. The present article reports the results of laboratory studies (10-d adult and 22-d larval toxicity studies assessing the chronic toxicity of thiamethoxam to adult honey bees and larvae, respectively) and a colony feeding study, with 6 wk of exposure in an area with limited alternative forage, to provide a prewintering colony-level endpoint. The endpoints following exposure of individuals in the laboratory (10-d adult chronic no-observed-effect concentration [NOEC] for mortality 117 µg thiamethoxam/kg sucrose solution, 141 µg thiamethoxam/L sucrose solution; 22-d larval chronic NOEC 102 µg thiamethoxam/kg diet) are compared with those generated at the colony level, which incorporates sublethal effects (no-observed-adverse-effect concentration [NOAEC] 50 µg thiamethoxam/L sucrose solution, 43 µg thiamethoxam/kg sucrose solution). The data for sucrose-fed honey bee colonies support the lack of effects identified in previous colony-level field studies with thiamethoxam. However, unlike these field studies demonstrating no effects, colony feeding study data also provide a threshold level of exposure likely to result in adverse effects on the colony in the absence of alternative forage, and a basis by which to evaluate the potential risk of thiamethoxam residues detected in pollen, nectar, or water following treatment of bee-attractive crops. Environ Toxicol Chem 2018;37:816-828. © 2017 SETAC.