Clomazone herbicide impairs bioenergetics in mitochondria isolated from the thorax of honey bees (Apis mellifera L.)

Abstract

The excessive use of pesticides on crops has caused an increase in animal mortality, contamination of soil, water and food, in addition to being identified as one of the causes of death of bees. Despite being quite effective, the herbicide clomazone (CLZ) causes widespread environmental contamination due to its high solubility in water (1,100 mg.L-1), and its residues can remain in the environment for up to 130 days. Mitochondria are responsible for producing the majority of the ATP in cells, and in bees, the thorax, as it is where the wings are located, is the place with the greatest ATP production. The objective of this work was to evaluate the effects of the herbicide CLZ on mitochondria isolated from the thorax of honey bees (Apis mellifera). The effects of CLZ (100, 125, 150, 200 and 250 µM) on mitochondria were evaluated by determining oxygen consumption, ATP production and generation of reactive oxygen species (ROS). When energized with pyruvate + malate (complex I substrates of the respiratory chain) CLZ did not show significant results in any of the concentrations used, however, when energized with succinate (complex II substrate of the respiratory chain) a dose-dependent stimulus in mitochondrial respiration was observed. Mitochondrial ATP levels were significantly reduced in a dose-dependent manner at concentrations above 125 µM. CLZ did not significantly induce the generation of ROS at any of the concentrations studied. Thus, the results of this study indicate that CLZ toxicity in honey bees may be related to changes in mitochondrial bioenergetics.