Bees! From honey bees to bumble bees, solitary or colony-forming, these insects have shaped modern agriculture. So why, exactly, are bees important?
Unloading honey bee hives for use in almond orchards begins under a winter sun. Finally freed, millions of bees fly around in all directions for a cleansing and orientation flight.
Photo courtesy Science Photo Library/Eric Tourneret/Visuals Unlimited
In The Bee (Princeton University Press and Ivy Press, Limited, 2014), Noah Wilson-Rich, Kelly Allin, Norman Carreck and Andrea Quigley provide a window into the vitally important role that bees play in the life of our planet. This richly illustrated natural history of the bee takes an incomparable look at the astounding diversity of bees, blending an engaging narrative with practical, hands-on discussions of such topics as beekeeping and bee health. The following excerpt is from chapter 2, “Anatomy and Biology.”
Bees are unique in many ways. In their anatomy they are similar to their carnivorous wasp ancestors, but in their biology they have evolved into something entirely different. Most bees do not have hardened mandibles (mouthparts) for chewing flesh; they sip nectar from flowers using a specialized proboscis. Bees are not parasitic within other animals like some wasp larvae, but some are social parasites, rather like cuckoos. Bees focus their diet on pollen and nectar, and play a vital role in the pollination of many species of flowering plants. Furthermore, from a human perspective, what really makes bees unique is their significant agricultural, economic, and scientific importance.
Bees are amazingly effective pollinators, in part because of their sheer numbers. Honey bee colonies have tens of thousands of individuals—perhaps up to eighty thousand—per colony. It only takes one bee to visit, for example, one almond flower, and then a second almond flower, to make an almond. And there are well over a million honey bee hives in the handful of Californian counties that produce almonds for the entire United States and regions beyond. Further multiply these numbers by the more than 130 crops that bees pollinate worldwide, and then factor in all the countries around the world growing fruits and vegetables, and you will begin to get a sense of the vital importance of bees to agriculture. These figures also demonstrate how massively effective bees are in driving our current agricultural practices. However, it is not just honey bees that are vital to our agriculture; many other types of bee are terrific pollinators too, including bumble bees, mason bees, and squash bees among others.
In the USA, honey bees are estimated to contribute over $15 billion annually to the economy. However, the honey bee population has been declining drastically since the 1980s, due to the onset of new diseases and pests, pesticides, and habitat loss, and this decline has coincided with an increase in agricultural demand. The result has been a rise in the price of food, especially in the case of almonds, which up to now have relied entirely on honey bees for pollination. The blue orchard bee (Osmia lignaria) has recently been introduced as a pollinator in commercial almond orchards, and other bee species are being studied as possible pollinators for this crop. Bumble bees, too, are used for crop pollination and make a vital contribution to the global economy. In China, a shortage of bees means that human laborers now pollinate some crops by hand. And even in the United States some farmers are turning to human hands equipped with pollination wands and swabs—a technique already used on at least one urban farm in Boston—as a means to guarantee crop yields.
The research value of bees is enormous, and not only for their contributions in the field of agriculture. Bees can be trained, and the blue orchard bee is a focus of research to train the bees to a target— fruit blossom scent—for increased pollination efficiency. Given that the life span of a worker bee is typically a few weeks to a few months, bees are also used in research relating to age-related disorders such as Alzheimer’s disease, studying relationships between aging, memory, and behavior. Bees also act as research subjects in the study of epidemiology, conservation, communication, sociology, genetics, chemical ecology, and more.
While bees share our world, they experience it quite differently. Cues from their surroundings—flowers, the sun, bodies of water—are all received by sensory mechanisms within specialized organs that are very different from ours. So, for example, a flower that appears white to humans may appear blue to a bee.
The eyes of the honey bee have been well studied. They see primarily blues and greens, with some other colors formed through combinations of visual cues. Remarkably, bees see what humans cannot—ultraviolet. Luckily, we can gain insight into what the world looks like to bees by using special ultraviolet filters. Through our eyes, the world looks more yellow and red, while the bee sees it as far more blue and purple. Bees cannot see the red end of the spectrum.
Most bees live inside nests that have little to no light, and where visual communication would be ineffective. Instead, bees rely heavily on vibratory communication. Bees often walk upon one another, exchanging signals by body shaking and, at least in honey bees, by so-called “dancing.” These signals are received through hair receptors throughout the surface of the bee body, including the antennae. Responses to touching and feeling vibrations are followed up quickly, and typically with some degree of specificity with regard to what the message is conveying.
The antennae receive chemical cues from odors. These odors can be airborne, dissolved in liquid (e.g., nectar), or transmitted directly from another bee through a behavior called antennation. As in humans, taste and smell are closely related, yet a mere 10 types of receptors in honey bees determine taste, while smell is determined by 163 different receptors. In other words, smell is far more important to bees than taste.
With their sense of smell, bees detect nearby floral patches and pick up the approach of competitors and predators. Many bees also signal to others of their species using chemicals called pheromones. Many of these signals are released from glands throughout the body, including Nasonov’s gland at the posterior end of the abdomen. Other chemicals picked up by the antennae from the environment include floral lures for pollination, or even eavesdropped cues that were not intended for the bee.
Bees do make sounds, but whether these are functional or merely byproducts is unclear. For example, drones occasionally make a short, loud popping sound when they ejaculate. This likely serves no purpose, but instead is a byproduct of his penis fully inflating and then air rushing out of his body as he explodes and dies.
Other sounds are made by air rushing through the spiracles along the abdomen—such as the quacking, tooting, and piping described in honey bees. A queen occasionally makes piping sounds during her earliest days as an adult. More piping is heard when there are multiple queens present, competing to be the last one standing.
Strangely, reports of bees making sounds in the key of A are increasingly common, ranging from piping in A-flat to buzzing in A during waggle dances. Beyond this, the auditory component of the waggle dance actually has been well studied and described.
Reprinted with permission from The Bee: A Natural History by Noah Wilson-Rich, with contributions from Kelly Allin, Norman Carreck and Andrea Quigley, and published by Princeton University Press and Ivy Press, Limited, 2014.
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