Living With Zombie Insects

What kind of bees live in graveyards?
‘Zom’bees!

In popular movies such as “Night of the Living Dead” Zombies are the “undead”, once living people brought back to life as flesh eating monsters. Zombies display different behaviors than their former living counterparts. The idea of mind alteration by other organisms is not entirely fiction. I have previously posted about Zombie Insects and Spiders that had their minds altered by a Virus, a Fungus, or a Wasp.

A new report in the journal, PLoSOne discusses the case of the Zombie Bees and mind control by parasitic flies.

(A) Adult female A. borealis.
(B) Female A. borealis ovipositing into the abdomen of a worker honey bee.
(C) Two final instar larvae of A. borealis exiting a honey bee worker at the junction of the head and thorax (red arrows).
Photo: John Hafernik, doi:10.1371/journal.pone.0029639.g002

A phorid fly, Apocephalus borealis, known to parasitize paper wasps and bumblebees has been found attacking honey bees. The female flies land on the abdomen of a honey bee and insert the sharp ovipositer into the body of the bee to lay an egg. The fly larva develops inside the honey bee. When it is time for the mature phorid fly larva to emerge, the infected honey bee uncharacteristically flies out of the hive at night. Zombie bees are attracted to light and will fly on cold and rainy nights and weather that discourages flight by most insects. The Zombies are often disoriented, walking around in circles, and staggering, unable to stand on their legs.

The larva of the parasitic fly makes a hole in bee between its head and thorax and crawls off to pupate. The bees do not survive. Not all infected bees leave the hive in a Zombie-like night flight. When bees remain in the hive, fly larvae can emerge and pupate within the hive. In this way, the hive can become infested by the parasitoids that can rapidly increase in numbers and infest large numbers of bees in the hive.

This news comes as a surprise to many bee keepers who watch their hives carefully. The parasitism of honey bees may represent a recent host shift of the phorid fly from attacking primarily bumblebees to now attacking honey bees. This parasitoid may be adding to the increased loss of honey bee hives over the winter (referred to as colony collapse) that many bee keepers have experienced in recent years. One of the features of “colony collapse” is the abandonment of the hive by the bees. The Zombie behavior produced by phorid parasitoids could be responsible for hive abandonment.

Keep in mind that this is a newly reported observation and more studies and updates are anticipated over the next couple of years.