In ladybirds, a group of insects belonging to the beetle family, the brightness of their colour reveals the extent of their toxicity, says a study.
The study by the Universities of Cambridge and Exeter researchers also found that the more conspicuous and colourful the ladybird species, the less likely it is to be attacked by birds.
"Ladybird beetles are one of the most cherished and charismatic insects, being both beautifully coloured and a friend to every gardener," said Lina Maria Arenas from the University of Cambridge.
"The study shows that not only does ladybird colour reveal how toxic they are to predators, but also that birds understand the signals that the ladybirds are giving. Birds are less likely to attack more conspicuous ladybirds," Arenas added.
Although red ladybirds with black spots are most familiar, ladybirds are a diverse group of species and come in many different colours and patterns, from yellow and orange to even camouflaged browns.
The bright colouration of different ladybird species acts as a warning signal, telling potential predators to beware of the foul smelling, poisonous chemicals they use for defence.
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The researchers measured toxicity using a biological evaluation that counted the number of dead Daphnia -- tiny crustaceans -- in water containing the different ladybird toxins.
The results showed that five common ladybird species have different levels of toxic defence.
Those species with the most colourful and conspicuous colours against the natural vegetation where they live are also the most toxic.
The study was published in the journal Scientific Reports.