PW09 Pesticide I
8:00 AM - Wednesday
(PW141) Pesticide use and cholinesterase inhibition in cattle egrets (Bubulcus ibis) from the Colorado River delta.
Vega-Cazares, M.1, Garcia-Hernandez, J.2, Garcia-de-la-Parra, L.1, Betancourt-Lozano, M.1, 1 Centro de Investigacion en Alimentacion y Desarrollo A.C. (CIAD) Mazatlan Unit, Mazatlan, Sinaloa, Mexico2 Centro de Investigacion en Alimentacion y Desarrollo A.C. (CIAD) Guaymas Unit, Guaymas, Sonora, Mexico
ABSTRACT- Pesticide pattern use was investigated in the Colorado River delta and inhibition of the brain enzyme acetyl cholinesterase (AChE) was determined in 56 cattle egrets (Bubulcus ibis) collected in 3 zones of the Colorado River delta agricultural valley. Egrets grazing in wheat and alfalfa fields were captured from January to April 2004, they were stored on dry ice and transported to the laboratory for their dissection and analysis. Brain tissue was homogenized, diluted to 1:40 and analyzed by the Ellman methodology. To determine inhibition of the enzyme we incubated the sample with 2-PAM. A total of 30% (17/56) of the analyzed samples were subject of reactivation. Of these, 7% (4/56) presented more than 20% AChE inhibition, considered a critical level to preserve avian health. The mean normal AChE brain activity was 3 ±1.2 U/g. We observed dial AChE decreases in the months of January-February (Pearson -.4, P<0.05) as well as a continuous decrease in the activity from January-April (Pearson -.3, P<0.05) which reflected the pesticide application pattern: more insecticides were applied in March and April than in the earlier months of the year. Results from interviews with owners from the pesticide application business in the valley, showed that the most used insecticide was the organophosphate methamidophos which was applied to the 60% of the aerial sprayed wheat crops, followed by lambda cyhalothrin, dimethoate, and methyl parathion. Using government guidelines, we estimated that approximately 50,000 lts of methamidophos were applied to the crops in this season. We concluded from this study that the use of organophosphate pesticides had an effect on a proportion of cattle egrets from the Colorado River delta.
Key words: cattle egrets, cholinesterase inhibition, colorado river delta