Formula ladybugs with strong color are more toxic

Researchers decipher the ladybug formula
Almost everyone likes ladybugs. They are considered cute, should bring good luck and are even made of chocolate. However, as researchers from the British universities of Exeter and Cambridge report in the journal Scientific Reports, certain ladybug species are anything but harmless to ants and birds. The stronger they are colored, the more toxic the secretion, write the scientists.

Ladybug (Image: Alekss / fotolia)

Ladybug but to protect a poisonous secretion
The color of the wings of ladybugs reveals how poisonous they are to other animals. The individual species are characterized not only by an individual coloring, but also by the number of their points. In particular, most people think of the seven point (Coccinella septempunctata) when they talk about ladybugs. In addition, there are also many similar species, such as the Asian ladybug (Harmonia axyridis) and the two-spot (Adalia bipunctata) naturalized in Europe and the USA. Their color ranges from yellow, orange and red to a brown camouflage look.

In case of danger, the animals have a yellowish secretion of special pores, which smells very unpleasant, tastes disgusting and even deadly to attackers like ants or birds. The British researchers wanted to find out which ladybugs are the most poisonous and this is externally recognizable. For this they gave the poisonous secretion into containers with daphnia. The more of the small crabs died, the more toxic the scientists classified the secretion. As it turned out, the beetles with the most intense color, including the two-point, were also the most poisonous animals. In contrast, the inconspicuous yellow-brownish-colored conifer-ladybug (Aphidecta obliterata) proved particularly harmless.

Birds recognize the connection between color and toxicity in ladybugs
In further experiments, the researchers use UV light. They wanted to imitate the perception of certain birds. Then they made ladybug dummies and presented them to wild birds to test if predators recognize the connection between color and toxicity. As it turned out, the beetles were the least attacked with the strong colors.

"Ladybugs are among the most cherished and charismatic insects, both beautifully colored and the friend of every gardener. Our study shows that not only the color of the ladybug reveals how poisonous they are to predators, but also that the birds can interpret the signals of the ladybugs. Birds attack more conspicuous ladybirds less frequently, "explains Lina María Arenas, PhD student at the Universities of Exeter and Cambridge.

"Our results show us that ladybugs send 'honest' signals to predators because their color shows how well they can defend themselves," Dr. Martin Stevens from the University of Exeter. "Relatively inconspicuous species, such as the larch ladybug, have little defensive capability and are more concerned about not being seen, whereas eye-catching and colorful species such as the seven-spot ladybug openly display their good defenses to predators." (ag)