Scientists from the Universities of Regensburg and Mainz and the Max Planck Institute for Chemical Ecology discovered that the eggs of the European beewolf produce nitric oxide. The gas prevents the larvae’s food from getting moldy in the warm and humid brood cells. The results were published in the journal eLife.

Food stored in warm and humid conditions gets moldy very quickly and thus becomes inedible or even toxic. To prevent this, we use refrigerators and freezers as well as various other methods of preservation. Animals do not have such technical appliances and therefore need to find other ways to preserve food. The European beewolf Philanthus triangulum, a solitary wasp species whose females hunt honey bees, has evolved a successful method of food preservation. A female takes up to five honey bees into its brood cells where they serve as food for a young beewolf. Female beewolves prefer to build their nests in sunlit and sandy places. The nests are deep and therefore the brood cells are warm and humid. Such conditions are favorable for the development of the beewolf larvae; however, they also foster the growth of mold fungi. As a matter of fact, bees stored under such conditions in the lab were overgrown by mold within one to three days.