Neonicotinoids in bee and bee products: analytical methodology and application on a field study.

MICHLIG, MELINA; DEMONTE, LUISINA D.; MICHLIG, NICOLÁS; MAGNI, FLORENCIA; BELDOMÉNICO, HORACIO R.; REPETTI, MARÍA ROSA

Foz do Iguazú

Workshop; 7th Latin American Pesticide Residue Workshop; 2019

CEPARC-UFSM

Wind and bees are the most important world?s pollinating agents. Although the human diet is mostly based on anemophilous crops such as cereals, most crops are pollinated by bees. The impact of agriculture on this biological process is highly concerning not only because it can cause the death of thousands of bees in a short period of time, but also because of the long term chronic risks potentially involved.Neonicotinoids are controversial since studies suggested they can translocate to pollen and nectar of treated plants representing a potential risk to pollinators. Therefore, regulations severely restricting their use were introduced (e.g. EU recent legislation on imidacloprid, clothianidin and thiamethoxam). In Argentina, five active ingredients from this family are registered for use on a variety of crops (acetamiprid, flonicamid, imidacloprid, thiacloprid and thiamethoxam). Imidacloprid is authorized in various horticultural products, oilseeds and cereals with MRLs in the range of 0.01 to 1 mg kg-1. Imidacloprid has historical relevance because it was the first compound from this family with widespread use and is the most common neonicotinoid used in South America. Despite the great concern existing for the evaluation of the effects of these compounds on pollinators and on the environment, in these countries there is still a lack of information regarding this issue. This presentation will describe the analytical approaches to analyze beehive materials and their application to several assays on an imidacloprid field controlled exposure study. Firstly, imidacloprid translocation capabilities in sunflower pollen and nectar were assessed. For this purpose field trials were carried out following the frequent agronomic practice during two years, so, three field plots were planted: sunflower seeds treated at the commercial label dosage and twice this level, and a control without imidacloprid. Secondly, since imidacloprid residues were found in both pollen and nectar, an open field feeding study was carried out. For this, 30 beehives were displayed in a common field area and separated into 5 groups of 6 hives. To each group different imidacloprid concentrations were applied once a week during 7 weeks (500 mL per hive of sucrose solutions containing 0, 15, 30, 120 and 240 ng/g). These doses were chosen in concordance with concentrations found in pollen and nectar. Eight weeks after the end of the artificial feeding period, sampling of honey from hive body and honey super of all hives was performed. The analytical methodology for the different beehive components based on QuEChERS strategies was optimized and fully validated. Extracts were analyzed by UHPLC-MS/MS. Imidacloprid residues were found in concentrations related to the treatments. On sunflower plants, the highest levels were found in concentrations related to the potential exposure to bees at label rates. Results showed scare differences in colony behavior among the different feeding dosages. Of the total imidacloprid dose added during the 7 weeks up to 60% was found in honey. The continuity of these studies is in course, both to contribute with better methodologies considering the beehive matrices complexity and to consolidate the observed beehive behavior, being the determination of neonicotinoid occurrence in consumed honey also of our interest.