Efeitos do herbicida a base de glifosato Roundup Transorb® na tolerância térmica máxima de larvas de Chironomus sp. (Diptera:Chironomidae)

Abstract

Temperature is a factor that acts directly on living organisms, currently the average temperature of the earth is rising faster than the historically experienced, integrating climate change. Ectothermic aquatic organisms are susceptible to thermal variations outside the tolerated limits, in addition these limits can be compromised by anthropogenic pollutants. In this work we tested the effects of a glyphosate based herbicide Roundup Transorb® (RT) on the t h e r m a l t o l e r a n c e o f m o s q u i t o e s l a r v a e o f Chironomus s p . (Diptera:Chironomidae), that inhabit the sediment of waters in Pelotas region. This genus is used as bioindicator in many works and suffer consequences from exposure to various pollutants, so we tested the influence of RT on the variable thermal tolerance, using the Critical Thermal Maximum (CTMax) tests. Realistic concentrations of RT were chosen, and the CTMax tests was divided into a control group (T0) and two exposure groups, 1 mg/L (T1) and 10 mg/L (T10), totalizing 72 individuals tested. The acclimatation and exposition time in both tests was 24h. The results showed a reduced CTMax to individuals exposed to 10 mg/L, there was no difference between 1mg/L and control groups. We conclude that glyphosate causes a physiological impact on Chironomus sp. larvae that results in a decrease in maximum thermal tolerance, when individuals are exposed to 10 mg/L for 24h at 22ºC.