A female beewolf wasp with a honey bee she's killed.

Credit: Martin Kaltenpoth

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SYDNEY: The beewolf wasp cultivates bacteria in its antennae, and use them – like a form of medication – to protect its young from fungal attack, say researchers.

Though other insects are known to have symbiotic relationships with bacteria, the European beewolf (Philantus triangulum), a species of wasp that capture bees and other wasps and feed them to their larvae, is unique in harbouring them in its antennae.

The discovery may also be of use to scientists looking for new ways to fight human diseases, according to researchers.

Last year scientists found that the leaf-cutter ants of Central- and South America grow antibiotic-producing bacteria on their cuticle, the waxy outer layer of their exoskeletons. The bacteria inhibits the growth of a parasitic fungus, which could otherwise infect their food supplies.

Now, insect researcher Martin Kaltenpoth at the University of Regensburg in Germany, has found that female beewolves cultivate Streptomyces bacteria in the glands of their antennae and apply it to their nests before they lay their eggs. The larvae then take up the bacteria and apply it themselves to the silk threads of their cocoons, says Kaltenpoth.

To test the link, he observed wasps and their larvae in the laboratory and experimentally blocked the larvae's access to bacteria-containing secretions. He found that larvae with access to the bacteria had significantly greater chances of survival than those without the bacteria, most of which died from fungal infections.

Kaltenpoth presented his findings at a meeting of the Society for Experimental Biology in Glasgow, Scotland.

In the vast majority of these case of symbiosis, insects produce bacteria primarily for nutritional purposes, rather than to ward off disease and prevent infection, said Kaltenpoth.

"Other insects are known to cultivate various micro-organisms, but usually inside their guts, or nests," commented David Yates with government research body CSIRO Entomology in Canberra, Australia. "Cultivating bacteria in their antennae sounds entirely novel," he said.

"The most interesting aspect of the findings is the possibility that these antibiotic properties of the bacteria could be harnessed for human health benefit," said Yeates, who suggested that the bacteria might have some medical application. "Today's useless bug is tomorrow's wonder-drug" he said.

A different type of Streptomyces bacteria is already used in human medicine to produce an antifungal drug called nystatin.

"I don’t know whether the study of the beewolf-bacteria symbiosis will lead to the discovery of useful novel drugs, but it is certainly worthwhile to try and find out," said Kaltenpoth.

More information:

CSIRO Entomology