Signs of Fall 12: More That Just Honey Bees!

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Honey bee. Photo by C. Denger. Public Domain

(Click on the following link to listen to an audio version of this blog  … More that just honey bees

The western honey bee (Apis mellifera) is a product of specialized selection, breeding and domestication by human beings. The bee’s innate ability to make large, perennial colonies and great quantities of honey and beeswax was recognized and then improved upon by ancient people. They took the honey bee from a wild form whose honey-rich, waxy-nests were sought after by hunters and gathers, to a managed, domesticated form that could be more easily relied upon to yield its vital products.

The genus Apis probably had its origins in South Asia but rapidly dispersed across Asia, Africa and Europe during the Eocene. The first fossilized Apis bees in Europe have been dated to the Eocene-Oligocene boundary (about 34 million years ago). Honey bees, then, have been abundant all across Eurasia and Africa for a very long time. Apis bees, though, did not exist in the New World until they were purposely brought there by Europeans as part of the post-Columbian exchange of species.

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Wild bee Families. Chart from Wikimedia Commons

Worldwide there are 20,000 species of bees. Of these, there are only eight surviving species (and 43 subspecies) of honey bees. In North America alone, there are 4000 species of non-honey bee bees!  Honey bees are the most often discussed and visualized members of the bee community, but although they may make up a very large percentage of the sheer number of individuals in that community, they represent a very small percentage of its total species diversity.

It is not always easy, though, to recognize and describe the non-honey bee subcommunity of bees as a study published in the Annals of the Entomological Society of America (July 11, 2024) discussed. This paper described a Penn State study in which 26 volunteers drawn from the statewide pool of Master Gardeners  were intensively trained to recognize the non-honey bee species that might be found in Pennsylvania. The individuals in this group then collected over 9000 bees across Pennsylvania over a one and a half year period of time and identified 235 species.

A second volunteer group in this study was trained in the use of the photoidentification-app called “iNature.” These volunteers were then asked to survey non-honey bee collected bees from across the state. This second group, which was made up of 2000 individuals, only identified 92 species of non-honey bee bees.

This study emphasizes that the true biodiversity of a system can only be determined by highly trained individuals. To know the real complexity of a biological system, we have to look at it carefully with well-educated eyes!

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Beehives. Photoby Jonathunder Wikimedia Commons

Another Penn State study, which will be published in Science and the Total Environment (November 25, 2024), looked at the impact honey bees may have on the diverse community of wild bees in the United States. Western honey bees (A. mellifera) as we mentioned above are exotic species first introduced to North America in the Sixteenth Century in the early years of European colonization. The incredible number of these domesticated bees, their dense concentrations in their managed apiaries and their extremely efficient harvesting of nectar and pollen from surrounding plants are all expected to have significant effects on the smaller, individual populations of the 4000 or so wild bees species that are native to this continent. These wild species are vital pollinators especially for both crop and wild plants that are native to North America. Their decline could have serious impacts on the pollination rates of these plants.

The presence of honey bee apiaries were correlated with declines in six of the thirty-three genera of wild bees. Some of the negatively affected wild bees experienced direct impacts from the honey bees. For example, some wild bees were out-competed for nectar and pollen by the more abundant and more active honey bees. This was especially apparent in late seasonally active bee species. These bees became active when the honey bee colonies were at their peak seasonal sizes and the number of late blooming plants was much smaller than the mid-summer peak of available flowers.

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Wildflowers in a field. Photo by O. Sulvik. Public Domain

Other wild bees were affected by the habitat changes surrounding the honey bee apiaries. There was a high degree of urbanization and development around the honey bee hives and this increase in ground covering concrete and asphalt and reduction in native flowering plants had significant impacts on many of the wild bee species. In particular, ground nesting wild bees, which are as a group, weak, short distance flyers, had difficulty finding bare ground in which they could dig their nesting burrows near suitable flower sources.

Recommendations from this study included planting more late blooming, flowering plants and leaving more bare soil in urbanize areas so that the ground nesting bee species will have places to dig their burrows.

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Bumble bee. Photo by Alvegaspar. Wikimedia Commons

Also, another Penn State study published in Ecosphere (June 18, 2024) demonstrated that managed honey bee apiaries have higher levels of viruses than are found in the nearby nests and burrows of wild bumble bees. These viruses in the managed bee hives spread to the wild bees each spring probably by inadvertent contact between the honey bees and the bumble bees while they forage for nectar and pollen. Bumble bee nests and burrows had very low levels of these viruses prior to this spring inoculation. The authors of this paper recommended that bee keepers do all they can to maintain clean, healthy honey bee hives in order to minimize the threat of disease spread from the domesticated bees to the wild bee species.

This goal of maintaining clean, healthy, honey bee hives was the focus of a comprehensive study by a team of Penn State scientists and their paper published in the Journal/ of Insect Science (May 28, 2024).

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Honey bees entering hive. Photo by talkingwithbees.com

One third of all managed honey bee hives die each winter, and the chance of a hive failing is, logically, increased by severely low winter temperatures, but it is also directly related to high levels of parasites in the hive and the debility of the parasite weakened bees. Varroa mites are extremely common parasites of bees. Beekeepers who used anti-Varroa mite treatments had significantly higher winter hive survival rates than those who did not treat for these parasites. Further, the beekeepers who use multiple types of anti-Varroa mite treatments had better winter hive survival rates than those who used just a single type of treatment.

The researchers found no difference between the effectiveness of “hard treatments” (i.e. synthetic, anti-mite chemicals) and “soft treatments” (i.e. naturally derive, organic, anti-mite compounds). Any of these types of chemicals incorporated into an integrated pest management protocol were equally able to reduce mite levels and increase the winter survivability of the treated hives.

This study also noted the impact of precipitation on hive viability and vigor. Precipitation in the fall, winter and spring was directly correlated to increased winter survival of the hive. Precipitation in the summer, though, was correlated with decreased winter survival of the hive. Summer rains prevented the hive bees from foraging for nectar and pollen. Too many lost foraging days led to reduced hive food supplies and declining hive vigor.

 

 

 

 

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