Mexico Ledger community blog
Zombie Bees, Not a Halloween Hoax.
What sounds like a cheesy horror movie title is actually a relatively new threat to our most important commercial pollinator of agricultural crops. Threats to honey bees are certainly not new. There is the recent and still a problem colony collapse disorder and the ever present ill-timed and ill-placed insecticide applications. Also there are parasites, predators and diseases of honey bees.
Now there is a threat possibly more bizarre than the colony collapse disorder (CCD). A hive affected by CCD is found to have no older, adult bees. All that remains are the egg, larvae, pupae and newly emerged adult bees. The older, adult bees responsible for gathering nectar for honey making, tending to the immature bees (larvae) and doing other hive maintenance will have apparently flown away and not returned.
Unlike CCD, the cause of zombie bees is known. There is a honey bee parasite known as the "Zombie Fly" Apocephalus borealis. Parasitized honey bees become zombie bees or "ZomBees" displaying a zombie-like behavior. They leave their hives at night which can be characterized as a flight the living dead. Oops, sounds like a cheesy horror movie rewrite of the CCD plot. The difference is no one has been able to prove the cause of CCD. Theories abound from some likely combinations of causes to some unlikely causes.
Although the Zombie Fly parasitized honey bee will act similar a CCD honey bee, after a while the phorid fly A. borealis adult will emerge from the dead bees. DNA screening has shown these emerging Zombie Flies are the same as those previously seen and thought to only parasitize bumble bees. This is referred to as expanding their (host) range. Another unfortunate happening is the Zombie Fly expanding their (geographic) range. So, zombie bees or ZomBees (ZB) may be coming to a hive near you.
Tracking the spread of ZB is important to judge its impact on honey bees across the U.S. There is a web site with ZB information and a way to become a ZB hunter at: https://www.zombeewatch.org. By enlisting bee keepers and others interested in the wellbeing of honey bees an efficient method of tracking and data collection is available. At this time ZBs have not been found in MO. The closest infection is in eastern South Dakota. Most ZB infections are located in California.
The lifecycle of the zombie fly is the female fly lays eggs in a honey bee, they hatch and begin to eat on the honey bees insides, then emerge and pupate, then come out of the pupae as adults which mate and begin the cycle again by laying eggs. The bees become zombies near the end of the flies grub stage eating within.
Honey bees infected by the Zombie Fly leave their hives at night and are attracted to nearby lights where they may be found before or after they die. The presence of fly larvae in up to 18% of foraging bees from some California hives makes the Zombie Fly a potential contributor to hive declines. This would be especially likely if Zombie Fly infection is widespread and higher in areas that are experiencing hive declines from CCD.
ZomBee Watch provides information on ways to see out how widespread Zombie Fly parasitism is and to learn how often un-parasitized honey bees are attracted to lights at night for other reasons.
Becoming a ZB hunter is relatively easy. No double tap is required. After signing up at ZomBee Watch at: https://www.zombeewatch.org/, just watch under outdoor lights at night for dead, dying or seemingly confused, non-flying honey bees. Collect the honey bees in separate containers for each date and site, mark the containers with date and location information. Use tweezers to pick up the honey bees. Even dead honey bees can still sting if handled carelessly. The grubs of the ZB fly emerge from the dead honey bee and pupate into small, brownish pupae looking like a little seed. The number of bees, pupae and emerged flies are important to record on the ZomBee Watch web site.
Really dedicated ZB hunters can build light traps to collect honey bees at night. Plans and photographs of honey bee light traps can be found at the ZB Watch web site.
Anyone wanting to know lots about this can go PLOS, the peer review open access journal at: http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0029639