banner by Sarah Burns
by Margaret Farrell
Apis mellifera - the Western honey bee. They are often mistaken for their Hymenopteran cousins, the genus Bombus (bumble bees) and the genus Vespidae (wasps, hornets, and yellow jackets). All of these species share their coloration with a whole host of yellow-and-black mimics – leaving honey bees generally a little misunderstood. Americans appear to know that we have some kind of bee population problem, but the details are not always clear. Experts from multiple sectors have not exactly reached consensus on whether or not we are even experiencing a decline, and, if it is occurring, how much of a problem it really is. To clear the air, it is crucial to answer some questions from different voices in the controversy: Are bees really in danger, and if so, which bees are affected? How big of a population decline, when did it start, and why is it happening? Finally, what are the consequences?
Really, and Who?
To answer the first question, it is helpful to understand some pollinator ecology and honey bee history. Some insects are pollinators that inadvertently pick up some pollen from plants while eating or reproducing. Honey bees are great pollinators because they feed frequently and because their fuzzy bodies trap lots of pollen. A not very well known fact is that the honey bee is actually relatively new to North America. They were carried on ships to the British colonies in North America and followed the colonists across the continent. Soon, honey bees joined some 4,000 other native bee species.
The Native Pollinators in Agriculture believes that we should be concerned about a decline in managed pollinators, bees that are maintained by keepers for commercial purposes, as well as wild pollinators because they act as a buffer in managed pollinator loss. Concerns like these were echoed this past September, when the United States (U.S.) placed seven native Hawaiian bee species on the endangered species list. Interestingly, 2016 paper published in Nature Communications says just the opposite: the native pollinator population is actually not significant in commercial farming.
It is well worth noting that the disappearance of the honey bee due to human activity is problematic for reasons independent of human need. However, the headlines we see seem to be concerned primarily about our food sources, so here, the critical focus is on honey bees because they are widely used pollinators in commercial agriculture in the U.S. and numerous European countries. In order to consider the consequences of a population decline, we need to first consider magnitude and causes of the problem.
How much, and why?
A 2014 article from Global Research, a center for research on globalization, claims that American beekeepers began to notice a decline around 2006. In 2009, The Journal of Invertebrate Pathology published a study that declared a 61 percent decrease in honey bee colonies between 1947 and 2008. However, the paper cited multiple points of weakness in the data collection. It was not until this past May that the Department of Agriculture published the results of its "first-ever Honey Bee Colony Loss Survey,” a more definitive study intended to provide concrete estimates. The survey estimates honey bees' worth as agricultural pollinators at around $15 billion, and reports an 8 percent loss in honey bee colonies between January 2015 and January 2016.
If we accept that bee populations are in decline and it is managed honey bees that are primarily affected, we can consider some factors leading to the population decline. In 2007, Pennsylvania State University entomologist Diane Cox-Foster and state apiarist Dennis vanEngelsdorp were the first to characterize “Colony Collapse Disorder,” a general descriptor for the phenomenon in which all workers of a hive disappear, leaving only the queen. They were responding to beekeeper David Hackenberg, who reported that 368 of his 400 hives had “collapsed” in the course of a few weeks. Since then, the term has mostly faded from scientific use as ecologists and beekeepers continue to gain understanding of the numerous causes for population decline, rather than one singular “disorder.”
One of the primary threats to the Western honey bee is the Varroa mite, which also is an invasive species. According to Eastern Pennsylvanian hobbyist beekeeper Cindy Ziesing, the Varroa mite is a parasite that thrives on male bees, called drones, during both their development and adult life, making drones prone to infection and death. Invasive species can be very successful in the absence of natural predators, and this has been the case for the Varroa mite – introduced in Florida in 1987, it now spans the entire U.S.
Several other factors are also associated with the apparent colony collapse. The Natural Resources Defense Council (NRDC) lists pesticides, loss of habitat and climate change as important causes. When bees forage on pesticide-treated plants, particularly the treated crops of commercial farms, they consume the pesticides through nectar and carry the pesticides back to their hives in pollen. A 2013 report on European bee populations lists seven harmful pesticides found in bees and their hives, three of which were banned in Europe that year, as they belong to a class of pesticides called Neonicotinoids, believed to be particularly dangerous to pollinators. The U.S. has not instituted a similar ban. Furthermore, the unintended effects of other pesticides can affect pollinator populations: an August 2016 scheduled spraying in South Carolina with the goal to kill Zika-carrying mosquitoes killed millions of honey bees.
As aforementioned, loss of habitat seems to be a major problem affecting wild bee populations. Ziesing emphasizes its impact in suburban areas, a point of interest for smaller managed populations. “People are grooming the lawns in their neighborhoods to exclude all sorts of sources of beneficial nectar (i.e., “weeds”) that used to be allowed to grow in copses, at the sides of roads, etc. Suburban bees just can’t find the nectar and pollen in the quantities they need,” Ziesing says.
It is unsurprising to find that climate change affects pollinator activity since it is an underlying condition for most ecological relationships. However, this factor is less concretely understood. The concern with this factor is primarily phenological relationships – that is, the relationships between the cycles of different organisms. Climate change affects the time that plants flower because the warmer temperatures trigger a response in the plant, and honey bees depend on several factors, including a change in temperature, to determine when to begin their spring activities. Usually the two events are synchronized, but when temperatures change, the plants flower before the bees are ready to pollinate.
While a 2012 paper in Current Biology explains this asynchrony, it only acknowledges the possibility for its effects. On the other hand, other sources feel the phenomenon is more urgent – a 2015 article from Nature claims the asynchrony would more acutely affect wild bee populations, and reporter Marissa Fessenden at the Smithsonian draws on Dartmouth College researchers to claim that this is a concern for all pollinators, wild and managed. Evidently, the role of climate change on the bee population has not been cemented, though it is widely agreed that it is highly possible that it has hurt honey bees.
The effects of honey bee loss in relation to humans are potentially devastating. Crops that depend most heavily on insect pollinators include fruits, nuts, seeds and hay. However, the NRDC reminds us that several staple crops, such as wheat, rice and corn do not depend on insect pollinators. Additionally, humans are unlikely to go extinct if we are to lose honey bees entirely. However, honey bees do constitute an essential part of the food production process for many of our other foods and are vital in the survival of plants and other organisms. Without bees, we will experience a sharp decrease in the diversity of our diet and environment – an effect that can be felt in all parts of the U.S.
Having dissected the complex issue of honey bee population decline, we can make a few definite conclusions. Our activities as humans have tangible effects on all ecosystems around us. These effects, like all ecological phenomena, cycle back to affect us as well. The systems that we create that rely on other organisms are never fully under our control.