Honey bees are the most economically valuable pollinators of agricultural crops worldwide. One third of the total human diet is dependent on plants pollinated by insects, primarily honey bees. In North America, honey bees pollinate more than 90 crops. The monetary value of honey bees as commercial pollinators in the United States has been estimated to be about $14.6 billion annually. The economic value of honey bees in North Carolina over the last five years, has averaged $88 million in annual fruit and vegetable production (67.9%) and approximately $154 million in total annual crop productivity (24.5%). For these reasons the quantification and preservation of genetic diversity in U.S. honey bee populations is critical.
The U.S. honey bee population can be divided into two sub-populations. The managed breeding population is composed of two geographically separated populations managed and maintained by beekeepers and bee breeders in moveable frame hives. The second population is the unmanaged feral population that consists of bees living in a variety of nest sites, both artificial and natural. Studies that analyzed these two honey bee populations in the U.S. reported significant genetic diversity among U.S. feral honey bees and found that feral populations contained genetic remnants from early honey bee importation events. Subsequent studies showed that the western and southeastern managed breeding populations contained little within population variation.
The history of honey bee importations into the United States began in the early 17th century. Historical records show that the honey bee of Western Europe (subspecies Apis mellifera mellifera) was present in eastern North America by 1622, where it established a feral population. This population expanded in advance of European human settlers, such that Native Americans considered the local presence of honey bees to foretell the impending arrival of European settlers and called the honey bee “white man’s flies”(Jefferson, 1788). No additional introductions of honey bees are known to have been made until 1859. However, between 1859 and 1922, seven additional subspecies from Europe, Africa and western Asia were introduced into the United States, with varying measures of commercial success. Of the eight subspecies brought into the country, only three found favor with the beekeeping community and remain available today as selected “strains” from bee breeders. These subspecies (and the commercial designations under which their presumptive descendents are commonly sold) included: Apis mellifera ligustica, (Italian honey bees), Apis mellifera carnica (Carniolan honey bees) and Apis mellifera caucasica (Caucasian honey bees).
Feral honey bee (Apis mellifera) populations once flourished in North America. Upon the arrival and establishment of a parasitic brood mite, Varroa destructor, feral honey bee populations were largely decimated. Research has shown that the genetic composition of feral honey bee populations in North America were different than managed commercial honey bee populations, containing genetic remnants from subspecies imported during the early colonization of North America. While it has been implied that these once thriving feral populations served as a genetic reservoir of diversity for managed honey bee populations in the United States, no empirical evidence is available to support this claim, to date.
Due to the growing problems facing honey bees-such as Colony Collapse Disorder (CCD), miticide resistance, and other pathogens-it is important to preserve genetic variation within U.S. honey bee populations. Managed colonies nationwide have dropped from 3.27 million to 2.59 million since 1986 (21%). In North Carolina alone, we have gone from 180,000 to 100,000 in two decades (44%). Feral colonies have experienced a 90 to 95 % loss over the past two decades, however, research and anecdotal evidence suggest that the feral population may be recovering. This leads to the question of the status of feral populations. What is the genetic composition of this newly re-emerging non-managed population? Does the unique genetic identity that characterized feral populations from over a decade ago still remain, or is this new population simply composed of swarms from managed honey bee populations?