Comparing Migratory Beehives and Swarms
Ecologically, migration is the regular seasonal movement from one place to another in search of food, nesting places or better conditions. The Western honey bee, Apis mellifera, does not exhibit these traditional seasonal migration patterns, unlike other species in the genus, such as the giant honey bee Apis dorsata.
A. mellifera conducts its foraging trips out of a single, central location within a general radius (~10 kilometers). The colonies expand each season as the honey bees swarm to a new nesting location. This article is a continuation of the concepts covered in the natural beehive and commercial pollination, and will also examine the migratory beekeeping concepts that contribute to the surge of colony collapse disorder.
Migratory Beekeepers
While swarming is a form of a migration that happens once or twice a year, the practice of migratory beekeeping involves moving bees to take advantage of the major agricultural crops’ flowering periods. In large-scale operations, bees are transported to fields or orchards during key times within the season to enhance pollination and crop yields.
An example is the late winter transportation of honey bees to the almond trees in California. Once the almond flowers cease blooming, the hives are then transported to other areas for crops like blueberries, sunflowers, canola (rape), or tomatoes.
Migratory beekeepers manage a large number of hives, often in the thousands, moving them across states and countries to provide pollinators for agricultural demand. They can also extract honey during a strong nectar flow, producing monofloral honeys with flavours from the forage source.
Effects of Commercial Migratory Operations on Honey Bee Lifespan
Honey bees have not adapted to a frequently changing environment. Generally, when a colony swarms, that is the only form of “migration” involved, and I use “migration” loosely because no ecologist will agree that reproduction is “migration”. No matter., this swarm establishes a new colony under a new queen, and remains at that location until they die.
Commercial beekeeping introduces the same honey bee colony to the novel stresses associated with frequent hive movement resulting in health impacts like:
- Increased stress- the frequent movement of bees is stressful on colonies and results in weaker immune systems.
- Increased exposure to pesticides – migrating bees are exposed to higher levels of pesticides as they travel between agricultural areas.
- A reduction in lifespan – some researchers suggest that migratory bee lifespan is reduced when compared to the traditional beekeeping practices.
- Increased disease transmission – a combination of high bee population densities and weakened immune system can lead to the rapid spread of disease.
- Nutritional deficiencies – commercial pollination services are conducted in monocultural crops, limiting bees to a single type of pollen, which does not provide the required nourishment for optimal health.
When these factors are taken into account, one can see a link forming between the migratory beekeeping practices and the onset of colony collapse disorder1. Below, several management techniques for these effects will be examined.
Minimising Transport Stress
Migratory beekeepers can minimise, but not eliminate, the stress caused by moving bees. This process begins with timing travel to occur at night, when all the bees are inside the hive, helping reduce forager loss and heat stress. Once the hives are packed onto trucks, they are secured to reduce the physical stress associated with vehicle travel, and the hive entrance is shut. In hot weather, water and screened hive lids/bases are provided to assist with ventilation and temperature regulation.
Many beekeepers often inspect their hives prior to transporting for diseases and pests; weaker colonies are typically left behind as they may not withstand the stress. Once the checks are complete, the bees are moved to their new location.
After hives are setup at their new location, beekeepers can engage in post-transportation care such as supplemental feeding with syrup and pollen substitutes. Bees are generally given “rest periods” to recover from the travel (especially when moved long distances).
Reducing Pesticide Exposure
Commercial pollination services required for agriculture generally involve monocultures sprayed with pesticides to reduce predation by insects. Some pesticides, like the neonictinoids, are absorbed and distributed throughout the plant’s tissues, including the leaves, flowers, nectar and pollen. This effectively controls pests like aphids and whiteflies, but gives rise to harmful off-target effects that affect many species of important pollinators beyond the honey bees.
Minimising the impacts of pesticides on honey bee health revolves around proper planning and preparation. Beekeepers communicate with farmers and landowners throughout the pollination period to keep track of when and where pesticides are applied. Site selection for hive placement is a crucial factor. Its impacts can be further reduced by keeping hives away from fields recently or likely to be sprayed during the bloom, and timing pesticide applications to occur at night.
In monocultural areas, it is hard to ensure the availability of uncontaminated food sources for forage. Supplemental feeding may be insufficient if bees gather nectar and pollen from contaminated sources, leading to a greater likelihood a weakened next generation of brood, or colony collapse in severe cases. Additionally, the honey stores may contain traces of pesticide, and be unsuitable for human consumption.
Ultimately, managing the risk of pesticide exposure is done through a combination of beekeeper training and education about the chemicals and how they affect bee biology. On a larger scale, advocacy and legislation between farmers and commercial beekeeping boards can call for more stringent regulation on pesticide use and promote bee-friendly farming practices.
Preventing Disease Transmission
In commercial as in traditional beekeeping, disease management is a top priority. Regular hive inspection for pests like the Varroa mites and fatal diseases such as American foulbrood enables timely intervention. Should diseases be spotted, the hive is quarantined and treated according to local rules and regulations.
A combination of regular monitoring and beekeeping practices (eg integrated pest management, replacing old comb, supplemental feeding in times of dearth) reduces the stress on bees and brood nest. Beekeepers can also ensure that hygienic methods like cleaning and disinfecting clothing & equipment between inspections, and (where possible), using a separate set of equipment for each hive/apiary to prevent disease cross-contamination.
Turning to a bees-centric, perspective, beekeepers can choose to rear disease-resistant queen bees, as well as breeds genetically predisposed to more hygienic behaviours, like the A. mellifera subspecies carnica. Proper genetic selection can help build disease-resilient colonies and reduce the need for chemical interventions. Of course, these bees require adequate nutrition to prosper!
Addressing Nutritional Deficiencies
The short answer is supplemental feeding of sugar syrup and pollen substitutes, depending on the season. In spring and summer when the queen lays large quantities of eggs, the syrup and pollen patties described in Honey Bee Nutrition and Supplemental Feeding are sufficient for brood rearing. In places where bees form a solid winter cluster in the winter months, fondant should be placed on the top bars close to the cluster to assist with overwintering.
It should be noted that these are supplemental, not primary sources of food. Where possible, bees should be allowed to replenish their food stores from diverse floral sources. Providing food in the spring and summer helps worker bees build comb and raise brood; this can be beneficial between blooming periods where there is a breif scarcity of forage or nectar dearths. During the dry season, the water content in syrup provides the workers with carbohydrates and water for necessary basic hive upkeep.
A combination of the practices listed above can mitigate the stress experienced by bees in a migratory beekeeping lifestyle, all in order to avoid the onset of a shortened lifespan of the older bees.
Evidence for Shortened Bee Lifespans in Migratory Honey Bee Operations
Not addressing basic bee health leads to a reduction in their lifespan. Physical manifestations include weaker flight muscles, reduced body weight in adult bees and disrupted queen egg-laying. On a larger scale, this foundational weakening of the workers within the hive is a strong driver of colony collapse disorder.
A study from Simone-Finstrom et al., (2016) showed that migrating bees in North Carolina almond plantations lived for an average 18 days compared to the 20.5 days of traditional beekeeping hives. These bees also experienced greater levels of oxidative stress, which was directly related with the migrating intensity (time between hive movements). This paper produced further questions, such as whether small-scale transportation would have similar impacts, the degree of interaction between food shortage or foraging quality, and how a shortened lifespan influences the social structure in colonies.
Determining the exact length of a honey bee’s life is more intricate than the textbook definition of 4-6 weeks. While this is true in the spring and summer, during the winter months, bees can live up to many more months in their cluster, as a result of significant decreases in daily activity. Genetic factors, stress exposure, and nutritional qualities (in other words, the topics discussed above) play a role in the health of the queen and nest.
Harvesting Honey from Migratory Hives
Most migratory beekeepers harvest honey for the extra income, provided it meets the regional food quality standards. While a single-source honey is relatively poorer nutrition for bees, it makes for a great, consistent taste, with buzzing markets developing for monofloral honeys such as citrus and lavender.
Harvesting honey from the hundreds or thousand of beehives that belong to a commercial beekeeper is no small task, and many hands are involved in this industrial-scale process. As in traditional beekeeping, harvests typically occur in the late spring and throughout summer, with a few frames being left behind for the bees to consume as food in times of need.
Oftentimes, commercial beekeepers have contracts with health food stores for their monofloral honey, or supermarkets for the blended product. It should be noted that the food labels such as “organic”, “raw”, “pure” honey become vital here, and the consumer-facing aspect of honey has been addressed in Organic Honey Bees.
For bees in their natural habitat, honey is the stored food for times of nectar dearths or extreme weather events that limit foraging. In the winter cluster, this is used to ensure the hive survives into the spring. As colonies build up their numbers and prepare to swarm later in the season, the departing queen and worker bees gorge themselves on honey in preparation for nest at building at their new location.
Are Swarms a Form of Seasonal Migration?
For a superorganism like bees, reproduction is done through swarming. A. mellifera swarm once or twice per year, whilst other species like the Asian honey bee A. cerana, swarm up to six times per year. Further comparisons of the two species is available on the Scientific name of Bees.
While swarming can be considered a form of seasonal migration, it differs from migration in the traditional sense. As the old queen and [around half of the] worker bees leave their original hive, this can be deemed somewhat akin to migration; the bees travel to a new location with abundant resources.
This is considered to be a form of “local” migration, as new swarms settle within a few kilometers of their original hive, contrasting the long-distance migration of birds and butterfly species (such as the Monarch butterflies). Furthermore, swarming is a one-time trip; bees do not return their original nesting site with the change of a season, and individual honey bees only live for a few weeks.
For the Urban Beekeeper, swarms are a nuisance due to their residential environment. As such, they must be prepared to provide honey bee removal services to their neighbours during the swarming season.
How Apis dorsata Honey Bees Escape the Rainy Season
Native to South East Asia, the giant honey bees migrate in response to the seasonal changes and availability of flowering plants. The environmental triggers for this behaviour are multi-factorial, such as the onset of the monsoon season, or a significant decrease in forage at the end of major flowering periods.
In Northern Thailand, the trend appears to be that bees travel back and forth between highland and lowland nesting sites; with colonies producing reproductive swarms in the highlands and then to build nests at the lowlands (Robinson, 2021).
Depending on the season, an entire colony swarms to a new location without leaving daughter queens at that original location. A. dorsata‘s swarm decision-making process is not fully understood. Like A. mellifera, the worker bees turn into scouts who search for suitable nesting locations including tree branches, cliff faces and buildings. Once scouts find a suitable home, they conduct waggle dances to convince the swarm on the most suitable nesting site.
The research of Robinson, 2012 and Robinson, 2021 showed that A. dorsata have communal bivouacking sites where the giant swarms will “rest” for a short number of days before continuing. Resting sites tend to be resource rich, and multiple A. dorsata swarms will rest alongside each other before continuing on their journey, as shown in the image below.
Does Apis mellifera Perform Seasonal Migration?
Swarming and the nesting habits of A. dorsata were briefly examined. We can safely state that no, a honey bee swarm is not a form of seasonal migration. This article provided an overview on migratory beekeeping and the effects it has on honey bee health. Bees as pollinators are a major component of the agricultural industry, and it is the migratory beekeepers who provide this service at the expense of colony health. Research continues to show the detrimental effects of migratory beekeeping compared to traditional beekeeping methods.
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Footnotes
- The Science™ will tell you that intensive migratory beekeeping can influence health metrics, but will then state that colony losses are part of a multifactorial picture, not a single dominant cause. I say that stressors and novelties that come with migratory practices are large drivers of drastic health events like CCD ↩︎