Beewolves are solitary digger wasps that catch and paralyze bees or wasps, and use them as live food for their larvae. Female beewolves cultivate bacterial symbionts of the genus Streptomyces in specialized antennal gland reservoirs (pictured here in yellow/red). The symbiotic bacteria are secreted into the underground brood cells by the female wasp, and later, the larvae incorporate the bacteria into the silk of the cocoon. Here, the bacteria produce a cocktail of at least nine different antibiotics forming a protective blanket that fends off detrimental fungi and bacteria from infecting the larva during the up to nine months of hibernation. When the young adult finally emerges, it wipes its antennae on the surface of the cocoon to ensure that it carries the symbiotic bacteria along to the next generation. The beewolf-Streptomyces symbiosis evolved at least 68 million years ago, and is employed by about 170 species of wasps.
For more on the amazing life history of the Beewolf, watch “I Contain Multitudes”
Beewolf antennae were sectioned, stained with fluorescent markers and viewed in a fluorescence light microscope. The symbiotic bacteria are visible in antennal gland reservoirs in yellow-red, the beewolf cell nuclei in blue and the beewolf exoskeleton in green. The diameter of the antenna is approximately 150 µm.
Martin Kaltenpoth, PhD, Institute of Organismic and Molecular Evolution, Johannes Gutenberg University, Mainz, Germany.