The Role of the Bee
The next time you see a bee buzzing around, remember that much of the food we eat depends significantly on natural insect mediated pollination – the key ecosystem service that bees and other pollinators provide.
“If wild pollinator declines continue, we run the risk of losing a substantial proportion of the world’s flora”
The global and European situation with bees and other pollinators.
Bees and other pollinating insects play an essential role in ecosystems. A third of all our food depends on their pollination. A world without pollinators would be devastating for food production.
Who would pollinate all the crops? Hand-pollination is extremely labour-intensive, slow and expensive. The economic value of bees’ pollination work has been estimated around € 265 billion annually, worldwide. So, also from a purely economic point of view, it pays to protect the bees.
A review of factors that put pollinators and agriculture at risk
Bees make more than honey – they are key to food production because they pollinate crops. Bumblebees, other wild bees, and insects like butterflies, wasps, and flies all provide valuable pollination services. A third of the food that we eat depends on pollinating insects: vegetables like zucchini, fruits like apricot, nuts like almonds, spices like coriander, edible oils like canola, and many more… In Europe alone, the growth of over 4,000 vegetables depends on the essential work of pollinators. But currently, more and more bees are dying. The bee decline affects mankind too. Our lives depend on theirs.
Insecticides in particular pose the most direct risk to pollinators. As their name indicates, these are chemicals designed to kill insects, and they are widely applied in the environment, mostly around
cropland areas. Although the relative role of insecticides in the global decline of pollinators remains poorly characterised, it is becoming increasingly evident that some insecticides, at concentrations applied routinely in the current chemical-intensive agriculture system, exert clear, negative effects on the health of pollinators – both individually and at the colony level.
2. Over Farming
Bees’ woes have been pinned to a number of factors, including the mass conversion of pollen-rich meadows into heavily farmed land for staples such as corn and soy beans.
The Varroa mite (Varroa destructor)
Is an external parasite that has spread from its original host, the Asian honey bee Apis cerana, to nearly all Western honey bees (Apis mellifera) worldwide. Virtually all European honey bees are highly vulnerable to Varroa mites, although some honey bee strains (VSH, Russians) show partial resistance to the mites. This mite weakens honey bees by sucking hemolymph (“blood”) from its host and by transmitting bee pathogens. A female mite reproduces by invading the cell of a bee larva just before capping. Once inside, the female lays eggs to produce offspring that feed together on the developing bee. The mother mite and her adult daughters emerge from the cell with the young adult bee host. Eventually, at high infestation rates, the mites overwhelm and kill the host colony. Beekeepers control Varroa mite populations by monitoring mite infestation rates and applying chemical treatments when mite populations become too large. Due to increased concerns over the effects of miticides on bees and mite resistance to commercial miticides, researchers are developing alternative approaches (“softer” chemical treatments, the genetics of mite resistance in honey bees, mite pheromones and hormones, and physical treatments) to control this mite.
Nosema ceranae – this microscopic fungus can weaken or even kill colonies when the majority of workers become infected. Spores of the fungus survive on wax combs and stored food inside colonies. When workers eat these spores the fungus invades the lining of the intestine. Highly infected bees cannot digest efficiently and die earlier. Beekeepers use antibiotics and disinfection of hives to control this disease.
Thus far, more than 20 honey bee viruses have been identified. These viruses can impact bees in multiple ways, including killing developing larvae and pupae, decreasing the lifespan of adult bees, causing spasms and tremors, reducing cognitive skills, and impairing wing development so that bees cannot fly. Most honey bee colonies have multiple viruses, and the levels of these viruses can fluctuate throughout the year.
6. Bacterial Diseases
American foulbrood (Paenibacillus larvae) – is an infection that kills young bees (brood) inside the wax cells in which they develop. This dead brood becomes a source of infection spread by workers nursing young brood. Some bees can detect and remove the diseased brood and this stops the disease from spreading. Beekeepers also use antibiotics to prevent the disease.
Pesticides are usually man made chemicals designed to kill pest organisms, that may injure plants or animals including humans. Pests cause economic damage by reducing crop yields directly or by producing crop, or ornamental plant diseases, or by competing with crops, or by reducing animal and human health, or by damaging buildings and structures. Pesticides are categorized according to their intended use as well as by their chemical composition. Pesticides are widely used and are divided into insecticides/acaricides, used to control insects and mites or ticks, fungicides used to control plant diseases; rodenticides, used to control rodents; and herbicides used to prevent weeds from competing with crops, grasses or ornamental plants. Pesticides usually contain an active ingredient, with a known mechanism for killing the target pests. Pesticides vary widely in their safety to humans and the environment and are sold as a formulation with added ingredients that augment the action of the active material when mixed in water for application. More than 1200 chemicals are registered for use in the United States and are used in some 18,000 separate products sold under a variety of trade names.
Honey bee colonies are healthier and stronger with access to pollen from diverse sources of flowering plants. However, floral diversity in landscapes has been reduced by intensive agriculture (single crops, few flowering weeds, limited hedgerows) and urbanization. In recent years, the pollination of early crops (such as almonds in California in February) has further increased the demand for strong colonies at times of year with few floral sources. Furthermore, changes in climate patterns may also affect seasonal availability of flowering plants. This requires beekeepers to use artificial sources (sugar syrup, corn syrup, and pollen substitutes) to try to meet the increased nutritional demands of their colonies.
Honey bee colonies are headed by a single queen who mates with an average of 12 males, and thus honey bee colonies are extremely genetically diverse. Several studies have demonstrated that genetic diversity improves the disease resistance and productivity of colonies, including their overwintering ability. Furthermore, strains of honey bees can have different traits – some forage for more pollen, while others are more adept at hygienic behavior, in which diseased or parasitized brood is removed. Several breeding programs are underway to develop stocks of bees that are more resistance to diseases and parasites, are better at overwintering in specific climates, and are productive and gentle.
10. Queen Quality
The honey bee queen is responsible for producing all the workers in the colony, and she lays up to 1500 eggs a day. Poor quality queens can severely impact colony health. Queens with low egg-laying capacity can limit the numbers of health workers produced, while unhealthy queens can die or be killed by workers, causing a break in brood rearing that again limits colony growth and productivity. Poor quality queens are consistently cited by beekeepers as a major factor underlying colony failure, and a longitudinal study of colonies indicated that loss of a queen or lack of laying by a queen was one of the two factors linked to colony loss. Several factors seems to impact queen quality, including rearing conditions and mating number.
11. Global Warming
Figuring out exactly how something so huge as climate change effects bee populations is tricky, but possible. To get the details on why and how this is happening, researchers go out into the field and mess with individual flower patches.
Rebecca Irwin, an associate professor at Dartmouth College conducts her work at at the Rocky Mountain Biological Laboratory in Colorado. There, she investigates the effects of changes in phenology — or the timing of when something occurs. “When the snow melts earlier, the flowers are going to emerge earlier and they’re going to bloom earlier,” she says in the video. “We don’t really understand if the bees are going to follow suit.”
If the flowers are available, but no bees are around to pollinate them, that phenology mismatch might be a problem. To test this, Irwin and her team goes out into the field early in the year and shovels the snow away from patches of mountain meadows. That creates a patch where spring comes artificially early: the snow is gone and flowers bloom. The experimental results are yet to be published, but the fact that climate change is affecting the relationship between bees and the plants they pollinate is well on its way to being established.
A recent study in Science that shows bee populations are having trouble moving their ranges to cooler or higher regions to follow temperature shifts.
As temperatures rise, the southern limits of many North American and European bumblebee species’ ranges are moving north — by as much as 300 kilometers in some cases, researchers report today (9 July) in Science. But the northern edges of the bees’ ranges are staying in place, leading to an overall contraction of the insects’ habitat.
That would spell trouble for the many crops and other plants bees pollinate — a task accomplished not only by commercial hives.
“If we had to try and do what bees do on a daily basis, if we had to come out here and hand pollinate all of our native plants and our agricultural plants, there is physically no way we could do it,” Irwin says in the HCN video. ” Our best bet is to conserve our native bees.