Comparative susceptibility of Chironomus and Drosophila to exposure to each and combinations of the following stressors: desiccation, heat stress and starvation

Abstract

In natural ecosystems, organisms are usually subject to environmental stress. In order to understand the response to a combination ofthree stressors (desiccation, heat stress and starvation), two dipteran insects, Chironomus ramosus (aquatic) and Drosophila melanogaster(terrestrial) were chosen, the former being more primitive than the latter. The mortality level as a function of the duration of the exposureto stress revealed that these two evolutionarily distinct and ecologically diverse insects differ in their response. Interestingly, when thetolerance thresholds of C. ramosus and D. melanogaster to single and multiple stressors was compared, a synergistic effect was recordedwith much higher levels mortality occurring when subjected simultaneously to several stressors. Chironomus larvae were more vulnerablethan Drosophila larvae when subjected to all three stressors simultaneously. The findings of this pilot study indicate the ecological risk formacro-invertebrate biota posed by adverse environmental conditions.