Ladybug becomes powerful foe after ‘stealing’ toxins from invasive insect

In a thicket of prickly pear cacti near Valencia, Spain, a troop of predatory ants moves in for the kill. But their target—the white, shaggy-coated larva of a ladybug known as the mealybug ladybird ( Cryptolaemus montrouzieri )—is far from defenseless. As the ants mount their attack, the juvenile beetle tenses its muscles and expels a drop of bright red fluid. Called hemolymph, the substance is chock-full of carminic acid, a toxic chemical that grants the liquid a bloodlike hue and prompts the ants to abandon their assault. Now, new research has shown that C. montrouzieri larvae “steal” their carminic acid from an invasive bug that came to Spain from the Americas —even though the two creatures have no history of coevolution. Because many plants and animals ward off predators through chemical means, some predators have evolved ways to resist these toxins or even “sequester” them to use in their own defense. Poison dart frogs, for example, build up reserves of harmful alkaloids by feeding on toxic insects. Usually, such adaptations are a sign that two species have evolved alongside each other for an extended period. But as humans spread far and wide—introducing other species as they go—many animals were exposed to biochemical defenses they had never encountered before. The new study, published today in the Proceedings of the Royal Society B , shows that even in new environments, animals can adapt to the...
Source: ScienceNOW - Category: Science Source Type: news