Pollinator Sundays: Honeybees (w/ nutty poll)
Sun Feb 11, 2007 at 09:57:38 AM PDT
Everybody knows the honeybee. Its familiar yellow and black body can be found in nearly every corner the globe. Its famous product, honey--the original sweetener--has been cultivated for millennia. Nearly everyone I know has been stung by one (ouch!). And beeswax is the original candle. Lastly, and most importantly, it is an integral part of agriculture. Without the honeybee, there would be no fruits, vegetables, and grain.
The honeybee is the premier pollinator of choice in the Unite States. It will fly year round and is less picky than other bee species about it pollen and nectar sources. Each hive comes packed with tens of thousands of bees (65,000 on average), each of whom is capable of pollinating tens of thousands of flowers.
Best of all, hives are easy to manage and easy to propagate. What's not to like about the world's most famous domesticated insect?
The honeybee has been domesticated since ancient times. Beeswax has been found in Egyptian mummies. The Romans used honey as medicine.
The honeybee apis melliferia (which even in Latin means 'honey bee') came to North America with European settlers in the 1600s. Native bees prefer native plants, so the honeybee was needed to pollinate the imported European fruits, vegetables, and grains.
The honeybee quickly went feral (there are no 'wild' honeybees, just as there are no 'wild' house cats), and spread as far as the Rocky Mountains. They had to come to California by ship, as they couldn't cross the mountains on their own. It's too cold, and there's not enough food to sustain a population 65,000 colonists.
Life Cycle
Honeybees live in hives. There is one mated queen, tens of thousands of workers, and a few drones. The queen lays all of the eggs. This is her raison d'être. The workers do everything else: prepare the brood cells, forage for pollen and nectar, clean the hive, feed the larvae, feed the queen, feed the drones, and even cool the hive with the beating of their wings (Nature's fans).
Once an egg hatches, the larva is cared for by worker bees who are on nursery duty. The larva will eventually spin itself into a cocoon, and when it emerges, it looks like a honeybee. It's exoskeleton hasn't hardened yet, nor has its wings fully dried. Until these happen, it cannot fly. But it can still work! The new bee will probably be a nursemaid for a few days before switching to foraging duties.
If the queen lays an unfertilized egg, it is male, and in bee parlance is called a drone. Drones are quite unless to the colony. They cannot feed themselves, and they cannot sting and thereby defend the hive. They serve only one function: to mate. In times of scarcity, the queen will not lay any drones, and workers will kill them.
All of the workers are genetic females, like the queen. That means that they have two sets of chromosomes, whereas their brothers only have one. Unlike the queen, their growth has been stunted and they cannot mate or lay female eggs. They could lay a male egg, but in all likelihood, her sisters would destroy it before it came to maturation. (Egg-cheating behavior is being studied extensively in hive species, and bees are notoriously good police; wasps are not as good.)
When a foraging bee returns to the hive, she may do the famous bee dance to tell her sisters where the good flowers are. The dance is somewhat complicated, and bee researchers are still trying to figure it all out (and some have even theorized a link to quantum mechanics). The other workers sample the pollen and nectar, then follow her around and interpret her dance. If the flowers are good, the other workers will go to the coordinates indicated by the dance and hopefully find a cache of food. One thing researchers are certain on is that the speed of the abdomen waggle indicates the distance to the flowers. The faster the waggle, the closer to the hive. There is a maximum waggle speed for a bee, which translates to about 2 miles. The consequence of this is that bees can't tell their sisters about anything closer than 2 miles, and thus putting your hive directly in your orchard is great for the next orchard over, but not necessarily for your own.
Bees live until their wings give out (they tatter easily). A bee that is constantly foraging will probably live for two weeks. A bee may also die defending the hive from intruders. The stinger on a bee becomes dislodged when she stings the leathery skin of birds and mammals. The poison sack goes with it, and continues to pump toxin into the attacker. Bees can also swarm around an invader and form a heat balls\ that cook invading wasps and hornets, and it's not uncommon for a few bees in the center of the ball to take one for the team.
The queen, being the only reproductive member of the colony, must constantly lay eggs to replenish those who are being lost to attrition. She exerts her breeding hegemony via pheromones. The nurse bees feed the larvae a special blend of food that makes them develop into workers. But as the hive gets larger, not all the workers fall under her influence. When that happens, some workers may begin feeding the brood royal jelly, a concoction that makes the developing larvae grow into queens.
When a new queen is ready to be born, she begins beating her wings inside her brood cell. This is the queue for the old queen to get out of Dodge. The old queen and half the hive grab as much as they can carry and leave en masse--a swarm--and found a new hive elsewhere. The new queen emerges from her cell, kills all her rivals before they emerge, and then takes off for the afternoon to mate.
She'll mate with 10-20 drones (who die while inseminating her by exploding their phallus), and then returns to the hive to begin laying her own brood.
Click to see a Wikipedia image, and then click on the high-res version. You can actually see the tattered wings on this bee.
Threats to the honeybee
Honeybee hives are on the decline in the United States, for two reasons.
Globalization had a detrimental effect on the honey producers in the US. Most apiarists used to keep bees for their honey and beeswax, and pollination was a bonus secondary source of income. But as prices dropped in the late 90s and early oughts, many apiarists closed shop.
The second major factor is the decimating varroa mite. Once loose in a hive, it can kill it in under two weeks. A beekeeper may not even know she has an infestation until its too late. We humans have exacerbated the problem by using pesticides for too long to control mites. Now varroa is immune to our best mite-killing toxins, and we're resorting to desperate measures, like breeding cleaner bees and dusting hives with mite-eating fungi. (ht to Lashe for the first link)
We Californians ran into a major problem last year because there aren't enough honeybees to go around; the almond pollination nearly didn't happen, and the price of renting a hive hit an all-time high of $150. Some were shipped in from as far away as Texas.
We need alternative pollinators, and fast. Our pollination landscape isn't diverse enough. (Mason bees would be a good start :-) Also, native bees help honeybees with pollination. Pollination is a coordinated effort, it seems, which shouldn't come as a shock to anybody.
Effect of Global Warming
This diary series is about how climate is effecting our pollinators. In addition to the above pressures being put on honeybees, climate change is going to affect them negatively as well.
Drier weather isn't conducive to hive health. Hives need their honey stores to stay healthy over the winter. But with less water, the honey quality declines. Also, Africanized honeybees will move farther north as the globe warms and interbreed with the local population. The effects of Africanized bees can be debated ad nauseum, but it suffices to say that this far north, the aggressive Apis mellifera scutellata--the so-called "Killer Bee"--is not a desirable pollinator. (The situation in different in South and Central America, where the africanized bee is an effective pollinator.)
Since honeybees are a heavily-managed and highly-adaptable species, they will fair better than most other bee species. But without human caretakers, feral hives would decline rapidly due to varroa devastation and loss of habitat (i.e. openspace).
But what will happen to our California almonds if we have warmer winters? When will they bloom? For anybody not in the know, California's biggest agricultural export (in dollars) is almonds. Not only do we have the Sierra snow-pack problem, but now we must worry about when to get beehives into the orchards.
Seriously cool link: Check out Clan Apis, by Jay Hosler, the graphic-novel version of a bee's life cycle. It's an addictive read. You've been warned.
Next week: The humble bumblebee!
Previous Entries in this Series:
Part 1: Global Warming kills bees
Part 2: Mason bees
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