Entomology – Bees also run vaccination programs | Scientific technology

AN OLD SAW is there that there is nothing new under the sun. But it may come as a surprise that humans weren’t the only people who invented vaccination. Work which has just been published in the Journal of Experimental Biology by Gyan Harwood of the University of Illinois, Urbana-Champaign, confirms that the bees got there first. It also suggests that they are running what looks like the equivalent of high dose booster vaccination programs for children.

Being gregarious, bees are constantly exposed to the risk of diseases that invade their hives. Most animals that live in crowded conditions have particularly robust immune systems, which has long amazed entomologists that bees don’t. Indeed, they actually have fewer immune genes than most solitary bees.

Part of the answer, discovered in 2015, is that queens vaccinate their eggs by transferring protein fragments from pathogens to them before they spawn. These act as antigens that trigger the development of a protective immune response in developing young people. But this observation raises the question of how the queen receives her supply of antigen in the first place, since all that remains is royal jelly, a substance secreted by worker bees which are in the stage of their life (which precedes the period which they pass to fly around in search of nectar and pollen) when they act as nurses for the larvae. Dr Harwood therefore wondered if the nurses incorporated into the royal jelly they produced fragments of pathogens that they had consumed while eating the food brought to the hive by the foragers.

To test this idea, he teamed up with a group from the University of Helsinki, Finland, led by Heli Salmela. Together, they collected around 150 nurse bees and distributed them among six queenless mini-hives equipped with larval clutches to care for. Instead of nectar, they fed the nurses sugar water, and for three of the hives, they mixed this syrup with Paenibacillus larvae, a bacteria that causes a destructive beehive disease called American foulbrood.

In this case, to stop such an infection, Dr Harwood and Dr Salmela heat treated, and thus killed, the pathogens in advance. They also tagged dead bacteria with a fluorescent dye, to make it easier to track their subsequent fate. And, of course, fluorescent microscopy confirmed that fragments of P. larvae entered the royal jelly secreted by those bees which had been fed on the laced sugar water. Additionally, examination of this royal jelly revealed high levels, compared to royal jelly from bees which had not been dosed with P. larvae, an antimicrobial peptide called defensin-1. This substance is believed to help the bee’s immune system to ward off bacterial infections.

All in all, these results suggest that nurse bees are indeed, via their royal jelly, transmitting antigens to the queen for inoculation into her eggs. They also mean, because the larvae are also given royal jelly for the first few days after hatching, that the nurses inoculate their larval loads as well. Each baby bee is therefore vaccinated twice.

It remains to be seen whether this is simply a belt-and-brace approach or if it is in fact the equivalent of a first-order human vaccination in which the second dose multiplies the effect of the first. But anyway, it seems protective. Not so much of herd, as of swarm, of immunity.■

This article appeared in the Science and Technology section of the print edition under the title “Swarm immunity”