Table of contents
- A polarizing shift in focus
- The most lethal competitor of all
- Humans and their fragments
- Strength in numbers: a honey bee asset
- Blaming honey bees for the things we do
- We all play a role in bee decline
- Note and Reference
The landscape of beekeeping is in flux. Ten years ago, beekeepers were folk heroes, the saviors of our food supply. But since the so-called insect apocalypse began shifting attention to other bees, beekeeping has come under attack. Some keepers now feel like pariahs, finding themselves being cross-questioned like criminals. The problem? Native bees.
Recently, a sideliner in North Carolina with about 40 hives and a farmers’ market honey business described the change. He said he noticed very little pushback against honey bees throughout his 60 years of beekeeping, but all that is changing. He says within the last ten years the honey bee has become a “focal point for a generalized cultural angst about how we’re screwing up the world.”
Sadly, he points to environmental “zealots” who topple hives, poison colonies, and work to prohibit honey bees from natural or conservation areas. His question to me was, “What is the reality of competition between honey bees and native bees?” Good question.
Strange as it may seem, the meteoric rise of interest in native bees arose from Colony Collapse Disorder. After details of CCD hit the newsstand, non-beekeepers, environmentalists, and even school children began questioning apiary management practices and attacking beekeepers. People who knew nothing about insects wondered if honey bees and their keepers were damaging native populations of pollinators.
A polarizing shift in focus
Within a few years, legions of citizen scientists were designing monitoring protocols and taking courses in melittology. Photos of obscure bees stuck with pins were all over the internet and native plants replaced daisies and daffodils in garden plots. Slowly but surely, beekeepers became the bad guys.
Although the shift remains subtle, some beekeepers are feeling defensive. The question is how can beekeepers respond to accusations that they are causing bee decline, destroying the world order, or interfering with natural processes. As with most misunderstandings, a dearth of knowledge in both camps exacerbates the problem.
Some general knowledge about solitary bees can help you answer basic questions. The following issues concerning bee-on-bee competition—I’ve chosen my favorites—illustrate the murkiness of the competition question but also provide discussion points to ponder in advance.
Honey bees are not the only competitors
Rhetoric about bee competition usually translates into “honey bees vs native bees.” This dichotomy is erroneous because it ignores the third group, those bees that are neither honey bees nor native bees. Is that a significant number? Absolutely. And it’s huge. In fact, I suspect it’s the fastest-growing and most under-recognized pollinator group in North America.
It is nearly impossible to track introduced and adventive species, let alone stop them from spreading. Global trade has assured that insects can travel the world, so they do. Bees often arrive in the cocoon stage, holed up in a piece of wood or a bamboo cane. Soil dwellers can arrive with potted plants or agricultural products.
These often enter unnoticed and may reproduce for many years without being recognized. Because most people cannot identify any bees, they certainly won’t notice a new one in the mix. A new species may establish a home, replicate like rabbits, and compete with the locals before someone discovers it. The point to remember is honey bees are not the only “foreign competitors” on American soil.
The amount of competition varies with species
All organisms compete. In fact, it is competition that shapes life forms to fit their environment, sculpting them over time into something that works. Wolves compete for rabbits, dens, and mates. Humans compete for food, water, fuel, and money. Bees compete for nectar, pollen, resins, and nesting sites.
Asking whether Apis mellifera competes with native bees is not meaningful; it is simply the wrong question. The extent of competition changes with each species pair. Instead, you need to ask if honey bees compete with species number one, species number two, and species number three. Then keep asking until you get to 4000 or more. Even then, the amount of competition will vary with location, season, and the number and type of flowers in bloom. It will also change from year to year as temperatures, rainfall, and humidity fluctuate.
Bees compete for more than just food
When we envision honey bees competing with solitary bees, we usually think of food, specifically pollen and nectar. However, honey bees rarely compete for nesting sites. Most solitary bees would scoff at a honey bee pad, thinking it useless.
However, the same is not true for other introduced bees. For example, sculptured resin bees (Megachile sculpturalis) compete directly with native carpenters for nesting holes. The European orchard bee (Osmia cornuta) and the horn-faced bee (Osmia cornifrons) compete with native blue orchard bees (Osmia lignaria) for tunnels and cavities. And the alfalfa leafcutting bee (Megachile rotundata) competes with native leafcutters for hollow stems.
Bees with similar needs are more apt to compete. For instance, a bee that forages on the same flowers as a honey bee will feel the heat of a honey bee colony landing next door. But a bee that uses a plant the honey bees avoid is less likely to be affected.
Likewise, bees that forage in cold temperatures can often get the jump on early flowers long before honey bees sip their morning coffee. Other factors, like the size of the pollen grains, the flower shape, or the sweetness of the nectar, can dissuade honey bees and encourage others. In short, some species will suffer more, some less.*
Modern agriculture could destroy native bees
Because of their size, foraging range, division of labor, and perennial nature, honey bee colonies can out-compete many solitary species, and the denser the colonies, the worse the problem. But we need to temper that fact with the services honey bees provide for our agricultural crops. Many non-beekeepers do not understand how adaptable honey bees are to being moved from field to field, or how we have integrated that trait into our cropping systems.
Most native bee species—around 70 percent—are solitary ground-dwelling creatures you simply can’t move. If turned loose on a modern field, most of those bees would nest in the ground beneath the flowers. At the end of the season, harvesting and tilling equipment would macerate those nests, killing any larvae that survived the fertilizers and pesticides. The offspring of bees released outside the field might survive, but the solitary bees—being short-distance fliers—might be unable to pollinate the center of the field.
Even tube-nesting species have limited uses. For example, people often tout orchard mason bees as being “revolutionary,” but they have severe limitations. Although they can be relocated in the cocoon phase, the adults have short lifespans. Orchard masons pollinate relentlessly during their four-to-six weeks, but then they’re done until next year, useless for any additional crops.
Not all pollinators are bees
If you find yourself cornered by an upset citizen, listen carefully. Many will equate pollinators with native bees, something that causes even more confusion. While North America is home to about 4000 species of bees, the total number of pollinators is probably 4 or 5 times that number, maybe more.
The pollinator count includes many beetles, wasps, butterflies, moths, and flies, in addition to various mammals and birds. Aside from other bees, the competition between honey bees and most other pollinators is negligible.
Even monarch butterflies are less affected by honey bees than you might imagine. Although monarch larvae depend on the leaves of milkweed, the adults will consume nectar from many plants. Since no self-respecting honey bee I’ve ever met cares a whit about milkweed leaves, the level of competition is minimal.
Species loss is nothing new
Some beekeepers claim that honey bees and native bees lived peaceably together since the 1600s when the first Apis mellifera landed in North America. I don’t agree. I think the most vulnerable species—specialist bees that depend on a single plant—were likely weakened or lost during the initial wash of honey bees across the continent.
A multitude of microhabitats blanket North America, and we can assume many of these were once home to specialist bees. Like specialist butterflies, these bees depend on a specific food for their offspring, no substitutes or off-brands will do. Just as monarch larvae need milkweed leaves, specialist bees need pollen from a particular plant.
We can surmise that as the honey bees spread westward, they entered these unique habitats and changed them through their presence. If the honey bees coveted one of the special pollens, they could easily exhaust the supply, leaving the natives to starve.
So in contrast to some imaginary “peaceable kingdom,” it’s more likely that species decline began when the honey bees first arrived and continued throughout the next 400 years. By the time we began to catalog bee species, we were probably already seeing a select group: the survivors. The survivors—our present inventory—are those bees that prevailed despite the honey bee onslaught.
We will never know what was here before the honey bees because we have no records pre-dating Jamestown. But remember, species loss is not new; it is not a scourge wrought by contemporary beekeepers. No way. Species loss is something we’ve been finessing for a long time.
The most lethal competitor of all
However convenient it may be to blame honey bees, they are not the greatest threat to native pollinators. Not by a long shot. That distinction belongs to humans.
It is we humans who introduced exotic plants and animals. We also brought invasive plants, non-indigenous crops, livestock, and diseases. We invented pesticides, herbicides, air pollution, and water pollution. Worst of all, we fragmented our land, making it unsuitable for countless species.
Humans and their fragments
Those of you who know your island biogeography understand that habitat fragments play fast and loose with genetic diversity. A habitat island—say a park bordered by freeways, office buildings, or a baseball diamond—will not have a healthy flow of bees in and out.
The individuals that live within the small patch interbreed because mates are limited, a phenomenon that restricts the number of alleles for each gene. You can think of alleles as variations on a gene. In humans, simple alleles govern traits like eye color, height, and blood type, among many others.
The result of fewer alleles is inbreeding depression, which is a weakening of successive generations due to a paucity of genetic choices. Carving a small population of any species away from the larger population is the quickest road to local extinction.
Inbreeding because of isolation is tragic, but it’s not the only problem with fragments. For example, small fragments may be short on nesting sites or nesting materials. A dearth of nesting space may cause overcrowding in certain spots, which can enhance disease transmission. A small fragment may not have a sufficient water source or one that stays clean all year.
Fragments used for human recreation may be trampled or over-treated with pesticides. And the plants within a fragment have the same problems as the bees: decreased genetic diversity due to small populations. If a favorite host plant disappears, the dependent animals soon follow.
Strength in numbers: a honey bee asset
Honey bees are okay with fragments because they can fly long distances. If one spot isn’t good, the foragers simply choose another. But long flights are generally not an option for natives. So why don’t distressed populations within fragments evolve to become stronger fliers? Wouldn’t that be a natural adjustment?
It sounds reasonable, but I suspect sufficient variation related to long-distance flight is unlikely in a shrinking, detached population. But the real issue is one of time, not strength.
In contrast to most bee species, honey bees have a powerful division of labor. They have nannies, shoppers, egg layers, wax workers, undertakers, and refuse collectors. The foragers can take their time collecting provisions because it’s their only chore.
But in her short four-to-six-week lifespan, a solitary bee does the entire home-building, child-rearing, provisioning thing herself. She simply doesn’t have time to travel long distances to accumulate supplies and feed her young. She must act like a bee possessed, working hard and fast, maximizing efficiency.
If momma bee cannot accumulate enough food within her tiny fragment, she may raise only a small brood nest or none at all. If she shares a predilection for the same flowers as a local honey bee colony, the situation is dire. A band of honey bees with the sole mission of food acquisition can soar in, harvest, and leave the occupants to starve.
Blaming honey bees for the things we do
I’ve spent countless hours obsessing over bee competition, and my conclusions have vacillated, swinging hot and cold. For a while, I believed honey bees were largely responsible for native bee decline, but now I view bee loss as a complex array of problems with many moving parts. The honey bee is but one cog in a large wheel.
I think the blame game is a waste of time. Lots of people wish we could go backward, rid ourselves of honey bees, restore the land to what it was, replace, revive, and resuscitate the environment. Perhaps that sounds good on paper, but if we are sincere, most of us from the world over would also need to pack up and leave. We are the worst of the offenders. We cannot live here without changing nature, and we cannot undo what’s already been done.
No matter what misdeeds honey bees may be guilty of, they didn’t create habitat fragments, nor did they arrive under false pretenses. It is disingenuous to point the finger at honey bees when it was humans who set the trap.
We all play a role in bee decline
Any human who participates in the global economy—and that includes me and you and the vandals who trash hives—plays a role in insect loss. If you visit a shopping center, drive on a road, plant a lawn, or use a cell phone, you are a player in the environmental destruction that is harming native species. Likewise, if you eat fruits, vegetables, or dairy products, you are benefitting from the work of honey bees.
The twerp who destroys hives probably caused the most loss when you consider extra trees must be cut and more oil pumped from the earth to replace the hives and fuel his misguided anger. (And to think his mother probably fed him bee-produced fruit and veggies.)
Furthermore, if you live in a subdivision that was prepped with a bulldozer, where every living thing was replaced with lawn, asphalt, and PVC pipe, that beehive in your backyard isn’t going to hurt anything. You needn’t feel remorse. The things valuable to native bees were long gone, even before your foundation was poured. If you want to go on a guilt trip, have at it, but don’t let anyone else do it to you.
Remember, too, that there is nothing wrong with helping the survivors. Plant flowers, leave habitat strips, minimize mowing, and turn off your porch lights. Doing what we can is a good thing, but we can only move forward from where we are, not from where we should be.
Honey Bee Suite
Note and Reference
*Prendergast KS et al. (2022) Pacific Conservation Biology doi:10.1071/PC21064. This recent literature review by Dr. Kit Prendergast compares many studies of competition between Australian native bees and the introduced European honey bee. As is the case here in North America, Australians imported European honey bees quite a while back, and similar to our own studies, theirs are often inconclusive. Some reveal substantial competition, others show none, and most fall somewhere in the it’s-hard-to-say middle ground.