In [...]]]> A small parasitic fly, Apocephalus borealis, may turn out to be one player in the failing health of honey bee colonies in North America. The parasite, a type of phorid fly, has long been known to parasitize bumble bees and paper wasps, but recent research shows that it may also attack honey bees.

In an article published yesterday in the journal PLoSOne, researchers explain that the tiny adult female fly lands on a honey bee abdomen and lays eggs by placing her ovipositor into the bee. The entire process takes two to four seconds. Seven days later the adult phorid larvae emerge from the area between the bee’s head and thorax. One to thirteen larvae emerge and leave the dead bee behind. The larvae then pupate elsewhere.

Oddly, honey bees parasitized by the phorid flies are attracted to light. Individuals are found to abandon their hives at night and fly toward sources of light where they remain until they die. In fact, it was large numbers of dead honey bees around lights on the campus at San Francisco State University that lead to the discovery of phorid fly activity in honey bees. Also of interest is the fact that many of the phorid flies were found to test positive for Nosema ceranae and deformed wing virus—pathogens often associated with dead colonies.

The authors of the paper speculate that the native phorid fly has recently evolved to accept the non-native honey bee as a host. If the fly had long been a parasite of honey bees, adult phorid flies, their larvae, or accumulations of dead bees around lights would have been noticed before now. As they point out, the honey bee is one of the most studied creatures on earth so it is doubtful this fly would have escaped detection.

If the fly has indeed shifted hosts, it is bad news for beekeepers. Unlike bumble bees and paper wasps—creatures without huge populations—a honey bee colony can provide a vast breeding ground for the flies. And at one to thirteen larvae per bee, it wouldn’t take long for the flies to overwhelm a colony. Furthermore, this tremendous population of flies could leave the hive and harm bumble bees and perhaps other wild bees as well. Scary stuff, great material for horror flicks.

I urge you to click on the link to the original article and enlarge the photo of a phorid larva leaving a bee. But I warn you, the image is graphic. It is enough to make me sick.

Rusty
HoneyBeeSuite

HopGuard is a naturally occurring food-grade alternative to chemical pesticides. It has been found safe to use even in [...]]]> For those of you interested in HopGuard, I just received notification from Mann Lake Ltd. that Section 18 approvals have been issued in Oregon, Washington and Idaho. Arkansas and Mississippi are supposed to be next.

HopGuard is a naturally occurring food-grade alternative to chemical pesticides. It has been found safe to use even in queen-breeding operations because it has no negative effect on egg laying.

For more information (and opinions) on HopGuard, please see HopGuard: the new Varroa pesticide and HopGuard: update.

For the record, I have no financial interest in either HopGuard or Mann Lake Ltd.

Rusty

A simple leg count is probably the easiest way to tell an arachnid from an insect. Insects—including bees—have six [...]]]> So what is a mite anyway? Generally, a mite is an invertebrate animal in the class Arachnida—a name that comes from the Greek word for spider. Like most other arachnids, mites have eight jointed legs.

A simple leg count is probably the easiest way to tell an arachnid from an insect. Insects—including bees—have six legs. In addition, arachnids have no wings or antennae. However, since both arachnids and insects belong to the phylum Arthropoda, they have many structures in common—one of these being a protective exoskeleton.

As a general rule, mites tend to be smaller than insects; some are even microscopic. Many types of mites—at least fifty or more—can be found inside a beehive, and most of these were carried there by the bees themselves. For the most part these are harmless, non-parasitic mites that were feeding on flowers, pollen, nectar, detritus, or other mites when they were picked up inadvertently and flown to the hive. These will usually die and become part of the frass that routinely collects on the bottom board.

Since mites have no wings, they often attach to insects and hitch a ride to a new location. Mites that move this way are called phoretic. Whether the mites in a colony of bees arrive by design or by accident, an overwhelming majority do no harm and may even be beneficial for consuming detritus.

However, some mites are parasitic, and two of these are famous for wreaking havoc on honey bee colonies. The first of these, Acarapis woodi, is known as the tracheal mite. As the name implies, this microscopic creature lives and reproduces inside the tracheae (or breathing tubes) of the honey bee. They bite into the wall of the trachea and suck the hemolymph or “bee blood.” This not only weakens the bee, but the wound allows the entry of secondary infections.

The most famous parasitic mite, Varroa destructor, is found on the external surface of both pupal and adult bees where it also feeds on the hemolymph. It is closely related to several other species of mite that have long been known to affect Apis cerana, the Asian honey bee. By mite standards, Varroa destructor is very large, and it is huge compared to the size of the host honey bee. Besides weakening the bees by consuming their body fluids, it is thought that Varroa mites carry a number of bee viruses that transfer to the bee through its bite.

Mites are spread easily and quickly from hive to hive. Beekeepers spread them during routine hive management and migratory beekeepers spread them from one apiary to another and one region to another. Bees also spread them when drifting, swarming, or robbing. Mites can even be spread when the bees are foraging. Several other species—including bumble bees, scarab beetles, and flower flies–have been found to carry Varroa mites from place to place. Although Varroa are harmless to these species due to their vastly different life cycles, the mites are glad to hitch a ride whenever the opportunity presents.

Rusty