Single bee is making an immortal clone army thanks to a genetic fluke

When hives of the African lowland honeybee (Apis mellifera scutella) collapse, they do so because of an invisible inner threat: the growing, immortal clone army of a rival bee subspecies.

That army is possible because the female workers of the rival subspecies — the South African Cape honeybee (Apis mellifera capensis) — can create perfect copies of themselves, with one individual found to have done so millions of times in the past three decades. With this perpetual-cloning ability, the Cape honeybees sneak into the hives of their lowland honeybee rivals and churn out copy after copy (no need for a queen). Even worse, these clones are freeloaders, refusing to do any work.
The Cape bee workers that take part in this parasitic behavior are the genetically identical descendants of a single worker that lived in 1990, according to Oldroyd. This single lineage of clones is responsible for the collapse of 10% of African lowland honeybee colonies every year.

Now that the researchers have a handle on how the workers can accomplish their bizarre cloning trick, they want to figure out how queens can switch on the gene that enables recombination and how the workers can switch it off. They also want to investigate the African lowland hives parasitized by Cape bee workers, to figure out what triggers the hive collapse.