APACAME - Mensagem Doce 117 - Resumos Técnicos-Científicos

The honeybee Apis mellifera L., 1758 belongs to the group of insects that are well studied. It is responsible for increasing the crop yields and furnishes products of high added value. A new approach was proposed to use the bee as a bioindicator of the environmental quality. The impacts of pesticides in bees can be assessed with biomarkers that account for the physiological changes induced by environmental stressors. However, the optimal use of biomarkers requires information on their seasonal variations. In this study, the attention was focused on seasonal patterns of type "b" esterases in honeybee not exposed to pesticides for validating the future use of these biomarkers. Thus, between September/2011 and Mars/2012, the tissue activity (TA) of acetylcholinesterase (AChE) and three carboxylesterases (CaE-1, CaE-2 and CaE-3) was studied on head extracts from Africanized honeybees. Preliminary results showed that TA of AChE was subjected to significant seasonal variations. The mean value was 16.50 µmol/min/g of tissue and could fluctuate with variations reaching +45% and -46% of the mean value. CaE exhibited similar variations and increased to reach the highest activity in December and January. For CaE-1, the mean TA was 26.23 µmol/min/g of tissue with fluctuations ranging from +20% to -17%. For CaE-2, the mean TA was 35.95 µmol/min/g of tissue with fluctuations ranging from +19% to -17% and finally for CaE-3, the mean TA was 18.31 µmol/min/g of tissue with fluctuations ranging from +21% to -15%. Based on the results already obtained evidencing that only small variation occurred in TA for the period mentioned, CaE from A. mellifera may represent good biomarkers. For AChE, there are discrepancies in the activities reported. Thus, further investigations are required to explain the large differences in AChE activities. For using the honeybee as a bioindicator, it will be necessary to study the variations of these enzymes after exposure to environmental stressors such as pesticides.

Keywords: enzyme, biomarker, seasonality, honeybee protection, environment.

Acknowledgement: We want to thank the Fundação de Apoio a Pesquisa do Estado de São Paulo/Fapesp (2010/00747-0)

Resumos Técnicos-Científicos

Tissue activities of esterases b (acetylcholinesterase and carboxylesterase) from Africanized honeybee