Singlepresence of a predatorcan cause you enoughstress to a dragonflyso that literallydie of fear, even if it poses no real threat, a team of Canadian biologists has found, publishing their findings in the journalEcology. ? How prey respond to the fear of being eaten is an important issue in ecology ?, explains Locke Rowe, a co-author of the research.
In their experiments, Rowe and his colleagues grew larvae of the speciesLeucorrhinia intactain large aquariums where there were also predatory fish and insects that the dragonflies could see and smell (although they did not know that the fish could not reach them), while another group stayed in water tanks with no predators in sight. Larvae exposed to the presence of fish or insects that posed a threat had asurvival rate between 2.5 and 4.3 times lowerthan those not subjected to the same stress. In a second experiment, the scientists observed that el 11% of juvenile dragonflies in the presence of predators diedin the process ofmetamorphosistowards adult insects. In a fish-free environment, the mortality rate was much lower, just 2%.
“As we learn more about how animals respond to stressful conditions – both due to predators and other natural factors, and caused by human action – we see thatstress increases the risk of dying“Rowe clarifies. The findings could be applied to multiple organisms, say the researchers, who argue that there is still much to know about the lethal effects of stress.
