Stress Is a Real Killer---for Dragonflies

Dragonflies can literally be scared to death of fish. Who knew? In a study published in November in the journal Ecology, researchers found that dragonfly larvae reared in the presence of fish were four times more likely to die before reaching adulthood, compared to larvae raised in an environment without predators. Similarly, 2.5 times more dragonflies croaked when raised in the same tank as an invertebrate predator. The larvae were kept in cages in full view of the predators, although the cages kept the predators from entering, and each one contained a small cup where the larvae could hide. The study also found dragonfly nymphs raised in tanks with a fish were 10 percent more likely to die while metamorphosing into their winged adult form that we know so well. Apparently growing up is not only stressful for humans, and being constantly reminded of one's mortality doesn't help. (But of ...