Zanella, Alessandro (2010) Contaminazione ambientale di api da insetticidi neonicotinoidi. Approntamento di una metodologia analitica per la sua valutazione su singolo insetto. [Laurea specialistica biennale]
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Colony Collapse Disorder (CCD), the sudden loss of most honeybees of the hives represents a worldwide crisis. Honey bees are insects really important for humanity from both ecological and economical standpoints. Abnormal colonies deaths from 2005 to 2008 are registered and the phenomenon is mainly observed in the period of corn sowing (spring), that generally occurs using corn seeds coated with neonicotinoids. As a consequence, these insecticides have been blamed for CCD. This work of thesis was focused to the development of a method for the extraction of these insecticides (Thiamethoxam, Clothianidin, Imidacloprid, Acetamiprid, Thiacloprid and Fipronil) from single bee using a mixture of methanol and water with recoveries higher than 90% using concentration levels from 50 to 400 ng/bee. Four instrumental method (UFLC/DAD) were optimized for different kind of samples; LOD are of about 1,5 µg/L and the precision for real samples (bees) for these methods results high also for low concentration level (measure error estimated about 5 % at 0,04 mg/L and less than 1,5% at concentration level higher than 0,2 mg/L). Two possible ways of environmental exposure and intoxication of honeybees to neonicotinoid insecticides were studied: the atmospheric emission of particulate matter containing the insecticide from the seeder and the translocation of the systemic neonicotinoids from the coated seed to guttation drops of young corn plants. Quantitative measurements conducted in open field demonstrate that both these mechanisms may represent ways of lethal dose contamination for bees. In honeybees sampled after their passage through the contaminated cloud originated from the seeder were found concentration of neonicotinoids from about 400 to 500 ng/bee. Those concentration were higher than the lethal doses and in fact the honeybees died in a few hours after the sowing. Humidity is a crucial factor for the contamination of the honeybees during sowing and in high humidity conditions the concentration of neonicotinoids found is 2 to 4 times higher than in low humidity conditions and so bees die faster. In honeybees sampled dead after hours or days after contamination no neonicotinoids were found. This problem was studied and we demonstrates that the mechanism of degradation originates from a metabolic way performed by bees or by microorganisms that lives into bees. UFLC/DAD, Guttation drops, Seed coating, Powder from seeder, Neonicotinoids Degradation, Honey bee extraction, SPE, Methanol, Atmospheric emission, particulate matter.
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