Asian Bees Use Feces to Repell Killer Hornets

PNG readers know that giant Asian hornets unintentionally imported into North America pose a serious threat to domestic bee colonies because our bees have not developed a defense mechanism against the armored invaders with a lust for bee meat. {11.11.20} It may take thousands of years of evolution for such behavior to appear though natural selection. A recent discovery was made about how Asian bees defend their colonies against the predatory hornets. Asian honeybees paste pellets of animal feces around the entrances to the hive. This behavior surprised entomologists since bees are famously fastidious. Their honeycombs are wet and warm, perfect places for the growth of fungus and bacteria harmful to larvae, so they make an effort to keep clean. Researchers from Canada found that Vietnamese bees collect buffalo dung and other kinds of poo to plaster around the hive entrance. Later, they determined that the behavior observed in Vietnam is widespread among bees in Asia. [photo credit: H. Matilla]

plastered with poo

How the mechanism works is not understood yet, but the bees only paint the hive entrance after a raid from a predatory hornet. Investigators found hornets spend half the amount of time at nests protected with dung, and 94% less time trying to chew their way inside. Hornets target hives for destruction with secretions that the bees apparently counteract with feces, a sort of olfactory camouflage, or perhaps hornet repellent. Other insects, such as the hornworm moth caterpillar are known to cover themselves with feces for protection. Even mammals sometimes use dung. A recent study from China shows giant pandas wallow in horse dung as a means of insulating themselves from cold.