The varroa mite is a highly dangerous parasite to honey bees that has spread throughout the world and is one of the leading causes that causes hives to collapse (Ellis and Zettel). Over the years there has been a significant amount of research and a few solutions have been proposed. Several chemicals have been approved by the USDA for use in the United States. Many other tools have been designed that offer non-chemical treatments for varroa mites. One of the most interesting solutions is the use of bees that show large amounts of a trait called varroa sensitive hygiene. Varroa sensitive hygiene is defined as when, “Some bees can detect varroa infested pupae and will remove those pupae.” (Hunt 5). This greatly interferes with the varroa mite’s ability to reproduce. To counter the effects of the varroa mite, we should continue developing bees that have the genes for varroa sensitive hygiene because they protect the hive for several years and they do not have negative side effects that chemical treatments have.
Honey bees develop in the hexagonal cells they are known for making. The queen lays an egg in the cell. Three days later the egg hatches into a larva. After the larva is a certain age the cell is capped. While the cell is capped the bee goes through its prepupa and pupa stages. The bee then chews through the cap on its cell and emerges as a developed worker (Ellis and Zettel). When the hive has varroa mites present, a female varroa mite enters the cell shortly before it is capped. This mite is called the foundress mite (Ellis and Zettel). After the cell is capped, the varroa mite feeds on the developing bee and lays one male egg and several female eggs. The eggs hatch and mate in the cell and leave when the bee emerges from the cell (Ellis and Zettel).
The varroa mite and European honey bees were never supposed to mingle. The varroa mite is native to East Asia were it parasitically fed on the eastern honey bee. The eastern honey bee was well adapted to the varroa mite so the mites did relatively little damage to the colony. When the European honey bee began to be used in East Asia for agricultural purposes, the varroa mite jumped from the eastern honey bee to the European honey bee. The varroa mite then spread throughout the rest of the world. Today Australia is the only major country that has been spared from the spread of the varroa mite (Delaplane 122). The varroa mite feeds on the blood of both the developing bees and the adult bees. This shortens the bee’s lifespan and often deforms their wings and legs (Bessin). In many cases infestations from varroa mites kills the entire hive (Bessin).
Unlike chemical treatments and many other non- chemical treatments, bees that have varroa sensitive hygiene trait are not left vulnerable during much of the year. Currently speaking, the chemical options for treating varroa are the most effective at removing large percentages of varroa mites in a timely manner. The problem chemicals face is that they do not protect the hive against future infestations. Other non-chemical treatments face the same problem. Both the chemical and non-chemical treatments only produce short term effects. On the other hand, bees with the traits for varroa sensitive hygiene treat already existing infestations and prevents varroa mites from infesting the hive in future seasons. Even after the original queen with the varroa sensitive hygiene trait dies, and the next queen mates with drones that do not have the varroa sensitive hygiene trait the hive will still show a significant amount of resistance to the varroa mite because of the genes the new queen inherited from her mother (Harris).
It was my second year of beekeeping when my hive became infested with the varroa mite. I was still relatively new to beekeeping, but I knew that the varroa mite was not a diagnosis that was to be taken lightly. I saw disturbingly high numbers of bees crawling around in the grass in front of their hives with shriveled wings. Even more disturbing was when I would brush the grass to the side and see possibly hundreds of dead bees littered on the soil. I just felt scared. I knew that the varroa mite was known to kill hives regularly. I eventually decided to use a chemical treatment. Within a few weeks I had successfully reduced the number of varroa mites in my hive to a manageable number and I was able to remove the chemicals from the hive. Little did I know then that I had only won a battle and that the war was still raging. For years after I would constantly be having to treat for mites.
Bees with varroa sensitive hygiene are effective at eliminating mites for the long term and do not have any major side effects. In my own story with varroa I used a chemical treatment called Apistan and I was fairly happy with the results. Recently, I was shocked to hear that now certain breeds of mite are showing resistance to Apistan (Hunt 3). This made me rethink how beneficial chemical treatments were. In his article Tools for Varroa Management Caron included a chart that describes the benefits and disadvantages of many of the treatments for the varroa mite. The section on chemical treatments were plagued by the disadvantages like, “Potential for bee brood mortality and queen losses.” (Caron 16), “Increase in bee adult irritability; honey taste tainting.” (Caron 16), “contamination of hive components” (Caron 14) and finally, “Mite resistance” (Caron 14). Most of the non-chemical treatments were noted for being, “Minimally to not effective” (Caron 17) and, “Time consuming management” (Caron 18).
The honey bee is far too valuable to our society to lose. A study done by Cornell University found that honey bee pollination generates $14 billion of value each year (Hackett 2). We need to think of the long term consequences of how we choose to treat the varroa mite. With non-chemical treatments being ineffective and chemical treatments slowly strengthening the mites and damaging the hives they were meant to protect, introducing queens that have the traits for varroa sensitive hygiene is the only option that will serve us long term. By introducing bees that have the traits for varroa sensitive hygiene we can reduce the threat that the varroa mite poses to honey bees.
Bessin, Ric. “Varroa Mites Infesting Honey Bee Colonies.” Varroa Mites Infesting Honey Bee Colonies | Entomology, Entomology at the University of Kentucky, Apr. 2016, entomology.ca.uky.edu/ef608.
Caron, Dewey M. Tools for Varroa Management. Honey Bee Health Coalition, 17 Sept. 2015, honeybeehealthcoalition.org/wp-content/uploads/2015/08/HBHC-Guide_Varroa-Interactive-PDF.pdf.
Delaplane, Keith S. First Lessons in Beekeeping. Dadant & Sons, 2007.
Ellis, James D, and Zettel Nalen. “Varroa Mite – Varroa Destructor Anderson and Trueman.” Africanized Honey Bee – Apis Mellifera Scutellata Lepeletier, University of Florida, May 2016, entnemdept.ufl.edu/creatures/misc/bees/varroa_mite.htm.
Hackett, Kevin J. Bee Benefits to Agriculture. Forum, Mar. 2004. agresearchmag.ars.usda.gov/ar/archive/2004/mar/form0304.pdf.
Harris, Jeffery, et al. “Varroa Sensitive Hygiene and Mite Reproduction.” EXtension, articles.extension.org/pages/30361/varroa-sensitive-hygiene-and-mite-reproduction#.U_36IsVdU7k.
Hunt, Greg. “Parasitic Mites of Honey Bees.” Beekeeping, Purdue University, May 2010, extension.entm.purdue.edu/publications/E-201.pdf.