Honey bees — Varroa destructor and a parable (part 2)

Read part 1 here

In other news, it turns out that bees, arguably an invader themselves, though not a very successful one anymore if they ever were, given their reliance on domestication, have themselves been invaded. By the varroa destructor, no less (who said scientific names couldn’t be evocative, eliciting a knowing chuckle or smirk). Varroa destructor is a species of parasitic mite that co-evolved with the Asian honey bee. The story is predictable from there: Asian honey bees can survive with these mites, but other honey bees that have not evolved any resistance, cannot. And because people travel with their bee colonies, providing pollination services, and ship starter packages of bees to people needing new colonies around the world, the mite moved out of the range where the bees could coexist with it, into new ranges where they could not.

First into Europe and Africa, and then in the late 1980’s, into the United States. It is now established everywhere in the world that honey bees are except for Australia, though it keeps trying to make its way there too. Incursions were detected in Australia in 2016, 2019, 2020, and again in 2022, officials working quickly to trace and eradicate it when they happen. The mite cannot live out its reproductive life cycle outside a honey bee colony; it is entirely dependent on bees, but their dependence kills the bees.

Varroa mites attach themselves to the body of a bee and feed off its fat stores, often when the bee is still in the larval stage. The mites are about the size of a pinhead: small, but visible to the human eye. Proportionally, if a bee were the size of a human, the mites would be the size of a fully-extended human hand. Small to us, maybe, but big to a bee. Aside from attaching themselves to the bodies of the bees and eating their fat stores, and the bodies of the bee brood, damaging enough in itself, varroa mites are also carriers of viruses. Among these is Deformed Wing Virus (DWV), which sounds exactly like its name, and which when present is also very visible to the human eye. It causes the wings of the honey bees to be either shriveled and useless or missing entirely, making their already short lives (a worker bee in the summer lives about three weeks) shorter still, putting the survival of the colony as a whole at risk. Without worker bees who live long enough with enough strength to forage for nectar and pollen, there is no colony.