Parasitic Mites

Before parasitic mites entered the United States, a person could purchase a colony of honey bees and expect it to live for a number of years providing pollination service and producing honey. However, the arrival of parasitic mites in the mid-1980s dramatically changed beekeeping in the US. The first mite to be detected, the microscopic tracheal mite, quickly decimated honey bee populations. It was shortly followed by the Varroa mite, a somewhat larger parasite visible to humans. Click on today’s photo of a Varroa mite on a honey bee pupa.

Today, the Varroa is the most deadly parasite of honey bees. As it sucks the bees’ blood, called hemolymph, it vectors at least 15 honey bee viruses to the weakened bees. With the arrival of parasitic mites, the public noticed the absence of bees from locations normally covered with bees; clover fields were often completely devoid of honey bees. Left untreated, most honey bee colonies dwindled and died. Many beekeepers simply quit, abandoning empty hives. Others treated their hives with the miticides, Fluvalinate and Coumaphos. These harsh chemicals killed mites for a period of time, and then they became less effective. New strains of mites, resistant to the chemical miticides, replaced the original pests. Larger doses of miticides brought less control over the mites. Honey bees also experience unfavorable side-effects of miticides. The chemicals accumulate in beeswax honeycomb, contaminating the brood nest. Exposure to the miticides causes sterility of queens and drones which leads to early supersedure of queens and sometimes loss of colonies. These miticides also become highly toxic to bees when exposed to certain common agricultural chemicals. New attempts at controlling Varroa stress an Integrated Pest Management approach based largely on breeding bees that can live in the presence of parasitic mites. To manage bees without using harsh chemical miticides, the beekeeper needs to monitor hives for mites. Symptoms of mite problems include bees with deformed wings or multiple numbers of mites in a drone pupa cell.

--Richard

Honey Bee Tracheal Mites

A great die-off of honey bee colonies occurred in the U.S. in 1984. Beekeepers found their hives largely depleted of adult bees. A parasitic mite of microscopic size was found living in the breathing tubes of bees in the affected colonies. Honey bees breathe through breathing tubes, called trachea, located on the sides of their thorax. The thorax is the middle of the three segments of the bee’s body. These tracheal mites live almost all of their entire life within the breathing tubes of the adult bees. They weaken their host bee by puncturing the bee’s breathing tube and then sucking the bee’s blood. The puncture also leaves the bee exposed to a number of secondary infections. The life of the tracheal mite begins with a female mite entering a breathing tube of a very young honey bee, usually within the first 24 hours after the bee emerges as an adult. The tracheal mite lays eggs; they progress through a larval stage and develop into adults. Still within the breathing tubes, the tracheal mites mate with their siblings. The mated female mite leaves the breathing tube and moves to a newly emerged honey bee to begin the reproductive cycle again.

Beekeepers can interfere with the tracheal mite’s ability to reproduce by placing vegetable oil patties in the hive. These patties, made of solid vegetable oil and sugar, are taken up by the bees because of the sugar. The oil is distributed among the bees in the hive, thinly coating all of the bees. Tracheal mites are less successful in finding day-old bees when all of the bees are coated with oil. At Peace Bee Farm, we keep vegetable oil patties on the hives at all times. We add spearmint and lemon grass essential oils to the mix to make the patties more attractive to the bees. Vegetable oil patties are part of our integrated pest management plan. Resistant strains of honey bees have made the tracheal mite less of a killer today.
--Richard