Lazy moths 'make themselves taste bad so they don't have to bother avoiding bats'
15 December 2019, 15:37
Lazy moths make themselves taste bad so they don't have to bother avoiding predators in the wild, a new study has suggested.
Some of the less appetising winged insects are more nonchalant when attacked by bats while their tastier friends tend to employ evasive manoeuvres.
Moths were observed to see if they used ducking and diving tactics to avoid becoming the bats dinner.
Researchers also looked at the bats eating habits - seeing which types of moths were swallowed and which were spat out by the hungry mammals.
Many creatures in the animal kingdom have evolved defence tactics to evade and deter potential predators.
In moths, this includes chemical defences that make them less appetising, ultrasonic hearing to hear bats approaching and mid-flight swoops and dives to avoid being eaten.
Dr Nicolas Dowdy, of the Milwaukee Public Museum and Wake Forest University in the US, was prompted to study the moths after realising certain species of tiger moths were not bothered being attacked by predators.
They now think moths have evolved chemical defences that made them unpalatable.
In short - this means they can't be bothered to evade the bats compared to their more delicious moth counterparts.
Dr Dowdy said: "Strikingly, we observed that moths with weak or no chemical defences often dive away to escape bat attacks.
"However, moths with more potent chemical defences are more 'nonchalant', performing evasive manoeuvres less often."
According to the study published in the Frontiers in Ecology and Evolution journal, this correlation allowed the researchers to predict the evasive or nonchalant behaviour of the moths based on their palatability.
When considering why the insects did not just try to evade the bats anyway, researchers suggest that the method poses both risks and rewards.
As well as being exhausting, performing panicked evasive manoeuvres might help a moth avoid becoming dinner but it might also land it in a spider's web or away from a food source or mate.
Dr Dowdy speculated that unsavoury moths may often take the lazier and potentially safer option by relying on their chemical defences rather than roll the dice on an emergency flight.
It may be possible that this relationship between palatability and nonchalance exists elsewhere in the animal kingdom but future studies are needed, say the scientists.