Ladybugs are actually omnivores – they need leafy greens in their diet

Here’s a fun fact you may not know – ladybugs are predators. Just like lions are hunting for meat, ladybugs are seeking aphids for food. However, as the new studų from Cornell University has shown, ladybugs still need a whole load of leafy greens, because their aphid-based diet lacks some essential nutrients.

Ladybugs are technically predators, but for a balanced diet they need to eat plenty of leafy greens. Image credit: Gilles San Martin via Wikimedia (CC BY-SA 2.0)

Ladybugs are farmer’s best friends. They cause no harm to the plants and eat aphids, which can be a real problem in some gardens. And they look very nice too. However, while most predators obtain a balanced diet from their prey, ladybugs are different. They actually need leafy greens for their biological functions.

Scientists showed that ladybug males, like all male animals, need sterols, like cholesterol, to produce  sperm, hormones, and to maintain cell health. Ladybugs get sterol from leafy greens, which is why they eat plants as well as their main prey. Scientists say that this study is actually very important for farmers, who rely on ladybugs for pest control. It is important to know what ladybugs eat, in order to create an environment that suits them perfectly so that they would actually come to feast on aphids that cause significant damage to crops. Ladybug populations are declining in North America and knowledge like this may help reverse this decline.

Scientists collected seven different ladybug species and fed them on aphids that had very low sterol levels due to fava bean plant diet. Ladybugs were fed on different aphids and had different diets altogether. All of them survived, but their reproduction systems were significantly altered. Females that mated with omnivorous males (who ate aphids and leafy greens) laid more eggs. Furthermore, more of those eggs hatched. Their chances of reproduction were significantly better than those of females who mated with males reared on aphids alone. Scientists say that this uncovered the sixth appetite in the animal kingdom.

Animals are known to feed on five major nutrients – carbohydrates, fat, protein, sodium and calcium. Now scientists know that sterols are very important as well. Todd Ugine, author of the research, said: “There are only a few known appetites in the world and they’re very specific to essential nutrients, but here we have uncovered a new appetite in the animal kingdom”.

Ladybugs are farmer’s best friends and yet their populations are declining rapidly. Pesticides, herbicides and other chemicals are to blame, as well as changing habitat conditions. Hopefully researches like this will help restore their populations at least a little bit by creating fields that are more ladybug-friendly.


Source: Cornell University

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