They eat the eggs and larvae of competing species. Males are so active that they sometimes try to mate even with dead females. They are comfortable living in the city and pushing the native species out into the countryside. The eastern ladybird is an invasive species in the Czech Republic and is spreading rapidly. With winter approaching, they try to get into human dwellings. But the expert advises to throw them out of the apartment or house, because the starving insects can even bite people.
The eastern ladybug first appeared in the Czech Republic in 2006. It only took a few years for it to spread throughout the country, quickly outgrowing the domestic species. “They are suited to an environment changed by man, i.e. cities and towns. Our species of ladybirds, including the seven-pointed ladybird, used to live in cities, but today they remain in less disturbed nature,” explains entomologist Oldřich Nedvěd from the Faculty of Natural Sciences of the University of South Bohemia.
In its original habitat in Asia, the ladybug hides in rock crevices for the winter, but in the Czech Republic it now often flies into apartments and houses, where it tries to survive. The expert advises to throw the insects outside. People should get rid of it, especially in rooms where it gets hot. The heat does not slow down the metabolism of the ladybirds, as if they were wintering outside.
“Already before Christmas, they use up their fat reserves and get hungry and thirsty. And they go to see what they can bite into and suck out some water. And then they maybe pinch people because they want to suck something out of their skin, maybe they want to drink sweat, ” the expert explains how insects behave during the winter.
It is therefore better to throw it away in the fall so that it can find a suitable hiding place before the winter. “So if you don’t want to kill them in the freezer, which I admit. But in the cottage, where they usually don’t get hot, they will survive until spring,” says Nedvěd.
They mate for two hours every day
The journey of the eastern sunbeam from Asia to the Czech Republic was complicated. Because it kills aphids, people planted it in many places in the past, but often the species did not take hold. “When it was successful, the ladybug helped the farmers as they wanted. It stayed in place and did not spread,” explains the entomologist.
But over time, the beetle mutated on the east and west coasts of the US, increasing its voraciousness and ability to spread. At the time, there were also two small populations of Asian ladybirds living in Europe, which had escaped from greenhouses in southern France and the Netherlands. “Then a mutant from America got here and crossed with them. The hybrid then began to spread through Europe, now it is somewhere in Russia,” Nedvěd describes.
However, it does not mix much with the native species. “Ladybugs as a family have an extremely high sexual activity. They mate again every day. It takes about two hours. Every day with a different partner,” describes the expert. “When a ladybug is alone in nature and cannot find a partner, in five to ten days it is already so horny that it will want to mate with a suboptimal partner,” he continues.
A deprived ladybug can also smell the pheromones of other species, such as the seven-spotted ladybug, which it would not notice under normal conditions.
“The piquant thing is that the smell remains on the surface of the ladybird’s body even after death. So the horny males try to mate with the corpses of the females as well. It smells a bit to them, so they try,” explains Nedvěd. Even if different species interbreed, their egg usually does not develop. Only species that have diverged from each other recently can interbreed. “But since the parent species are similar, the hybrid is also similar to them and no strange monster will arise,” adds the entomologist.
The larvae eat each other
There are about 90 species of beetles in the Czech Republic, which people most often call ladybugs. The eastern ladybug belongs to the more aggressive ones, which are more voracious. “They can also eat a competing species. Adult ladybirds are armored and hard and do not attack each other, but they eat each other’s eggs and soft larvae. The eastern ladybird then eats more larvae and eggs of the hepteroptera than it does,” explains the expert, explaining why the invasive species is more successful.
“To a large extent, the two-spotted ladybird bounced back. Today, the seven-spotted ladybird is doing well in fields and forests. But before the eastern one came, the two-spotted ladybird lived with us mainly in cities, less so in the wild,” Nedvěd describes.
When the invasive species occupied the cities, it took the living space of the ladybug. “However, we cannot clearly say that the eastern one came and killed the two-pointed one, because it had been declining for fifteen years before the eastern one came. It just reached it,” he adds.
Eastern ladybirds are not the only non-native species that humans have targeted. “In Europe, we have several types of ladybugs that have been doing great for a hundred years and eating what we want them to eat. The cases where it has broken off the chain, such as the rabbit in Australia, are a small percentage, but they are easy to see,” he says expert. He mentions that there are rules that must be known in advance about the planted species and the environment.
For example, lynxes and lynxes are planted against various insect pests. Compared to ladybugs, their advantage is that they feed, or more precisely parasitize, on only one type of host. And so that they lay eggs in the caterpillars of butterflies or moths. The larvae that hatch from them then eat the caterpillar from the inside.
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