Borboletas como indicadores biológicos de qualidade do ar: um estudo nos parques urbanos da cidade de Osasco

Abstract

Air pollution in huge urban centers is a big problem today posing threats to people´s health and quality of life. This is the case of Osasco city in the Metropolitan Region of São Paulo where the present study was carried out. Presently heavy traffic in the major highways located in surroundings of this city is one of the major factors for its high index of air pollution. The quality of the air in the area is daily monitored by one of the nearby pollutants monitoring station of Cetesb, the São Paulo environmental agency. Studies on air pollution have been using Tradescantia pallida as a biological indicator for monitoring air quality due to its sensitivity, reproducibility of results and low cost. One premise of this study is that butterflies can also be used as biological indicators since they are sensitive to environmental changes and also both easily identified and sampled. This study also assumes that urban parks can be used for biomonitoring studies because the security for the traps and other materials used is more guaranteed than in other parks. It also assumes that urban parks located in Osasco are appropriate for carrying out this study due to its placement nearby the main roads of the city and highways. In this regard, four parks of the city were chosen and for each of them a gradient of urbanization was calculated taking into account their urban characteristics. The micronucleus test in quantifying T. pallida (Trad-MCN) was used in this study. This test consists of collecting flowers of the plant which were grown in pots and placed in each park for subsequent analysis under a microscope. Simultaneously to the collections of flowers, measurements of the concentration of the particulate material with 2,5µg diameter (PM2,5) were carried out using electronic appliance. Butterflies were captured using both traps Van Someren-Rydon and insect net. A search in a specific literature and also in specialized sites was necessary for the identification of insects. This study aimed to investigate the potential of butterflies as biological indicators of air pollution in the parks of Osasco comparing them with the results of quantification of micronuclei in T. pallida. In all the studied parks it was observed an increase in the frequency of micronuclei during the winter months, which coincided with the increased concentration of PM2.5. The inventory of butterflies pointed out that the most representative family was Nymphalidae in parks 1, 3 and 4 and the Pieridae family in park 2. Parks 1 and 2 had higher levels of pollution than 3 and 4. The diversity of butterflies in parks 1 and 2 are not as rich and abundant as in parks 3 and 4. In this last two parks, the levels of pollution and diversity of butterflies were compatible with the least polluted environments. The results showed that butterflies can be considered biological indicators of air quality in urban parks. They also showed that there is a group of butterflies that can be considered specific indicators of air quality. This study may provide knowledge to support public policy and also to encourage public participation in the environmental management of cities via simple in situ biomonitoring with butterflies.