What Are Bugs Worth?
Insects perform countless functions that improve our environment and our lives in ways that researchers are only beginning to understand
PICTURE THIS: You're sitting around, having a tailgate party before the big game, when yellow jackets swarm around the apple cider. Or: You're up on a ladder, washing the storm windows, and you find a big wasps' nest under the eaves. How do you feel? Bugged?
Most of us react to insects with annoyance or fear--and the instinct to swat--but according to a couple of enterprising entomologists, deep appreciation would be a more appropriate response. Cornell University's John Losey and Mace Vaughan of the Xerces Society for Invertebrate Conservation recently sat down at their computers, drew up a really big spreadsheet and toted up the cash value of some ecological services that native insects provide right here in the United States.
By ecological services, these scientists mean real work, done for free, by the six-legged creatures we ordinarily feel compelled to swat--work such as pollinating crops (native bees do $3 billion worth of pollination that would otherwise be assigned to hired honeybees) and pest control (when native insects chow down on alien invaders, farmers avoid $4.5 billion in crop losses). Then there's the lowly dung beetle--unappetizing in name, but without it, cow patties would just pile up on the range, attracting flies and parasites and preventing new plants from sprouting. Instead, thanks to the dozens of dung beetle species found in North America, bovine waste is swiftly recycled back into the ground, converted to fertilizer that plants can use and farmers don't have to pay for. Chalk up another $380 million annual service for American ranchers.
All in all, Losey and Vaughan added up a cool $57 billion in useful services that insects native to the United States perform each year, gratis, no need to send a thank-you note. And the scientists didn't even measure every single beneficial thing that native insects do for us--just a few of the services that were easy to measure because the data were already lying around in the literature. Their study was published earlier this year in the journal Bioscience.
If you're reading this magazine, then you may have a particular interest in the main service insects provide for us: They help keep America's population of native wildlife alive and well. Many kinds of animals, from native trout to game birds such as grouse and quail to colorful wood warblers and raptors such as American kestrels and Swainson's hawks, rely on insects as food. "If the insects that these wildlife species need to survive were to suddenly disappear, there's no way you could just go out and feed those animals some other food," says Losey. And here's where the big money comes in: Taken together, the wildlife species that rely on insects represent a $50 billion slice of America's outdoor recreation industry (including bird-watching and other kinds of wildlife watching, along with fishing and hunting).
The idea that intact, functioning ecosystems provide us with services--fresh air to breathe, clean water to drink--and that we can assign a cash value to these services has been circulating among biologists for a while. Losey and Vaughan's study, however, may be the first to assign an economic value specifically to wild insects. Losey says he got the idea for the project while investigating the effects of genetically modified corn on monarch butterflies. The corn did suppress pests, but its pollen also blew over onto stands of milkweed near the cornfields, killing the caterpillars of monarch butterflies.
affects nontarget insects, who cares? They're just a bunch of bugs,'" Losey remembers. "I said, 'Wait a minute, we do need to care!' I wanted to show people that we should care. So I asked myself, 'Can you put a number on how important insects really are?'" As it turns out, he could.
So insects are important to us, just by the nature of the ordinary things they do as they go about their daily lives. But scientists are also studying insects' special talents with the idea of applying these skills in new ways to make our lives better--or safer. Right now, for example, police teams use dogs to sniff for hidden explosives. But some day soon, your local SWAT team might bring out trained wasps to find the TNT.
A team of researchers with the University of Georgia and the U.S. Department of Agriculture has developed a cup-sized device called the "Wasp Hound." It's big enough to hold a few live Microplitis croceipes, a kind of tiny parasitic wasp. This species doesn't sting, and it can be trained--much like a dog, using a food reward--in just a few minutes to detect any one of a number of chemical odors, including a chemical used in explosives. When the wasps encounter the target odor, they trip a signal inside the cup so a light flashes. They're cheaper than trained dogs (although they don't live as long) and they're more sensitive than so-called "electronic noses." Preliminary studies show the wasps could also have agricultural and medical applications--they can be trained to detect the smell of toxic fungi that infect certain crops, and also the chemical odors associated with certain human cancers. So some day, when the doctor tells you to open wide, that may not be a tongue depressor he is inserting in your mouth.
Other researchers are looking into ways we can learn from insects' behavior. "We humans focus on centralized control, with a boss and a hierarchy of decision-making," says University of Illinois at Urbana-Champaign entomologist Gene Robinson. He is part of a team that, with support from the National Science Foundation, is studying social insects such as ants and honeybees as inspiration for new approaches to disaster response.
"When a honeybee colony faces a disturbance--say, a honey badger in Africa attacks the hive--there is no centralized control," Robinson notes. The queen doesn't lead the response. She doesn't send out scouts, have them report back with information about the situation, and then weigh her options. "Yet chaos doesn't result. Decisions are made. The colony defends itself effectively, in proportion to the magnitude of the disturbance."
If that all seems rather abstract, here's something easier to picture: Scientists around the world have been trying for decades to figure out how insects fly. The challenge is that insects seem to defy the laws of physics. Based on what we know about how flight works, it seems almost impossible that insects get airborne. But if we could figure it out, scientists believe we might develop tiny unmanned aircraft, or micro air vehicles (MAVs). Possible applications range from wartime surveillance to checking for victims in burning buildings to search-and-rescue after disasters such as hurricanes.
University of California–Berkeley biologist Stacey Combes didn't care about MAVs--she was just curious about how fast different insects could fly. Trouble is, stick bugs in a wind tunnel and most species opt out. Instead of flying their fastest, they give up and cling to the sides. Then Combes, a postdoctoral research fellow, found the brightly colored orchid bees of the New World tropics. Just open a jar of cinnamon oil and they come flying. Combes set up a portable wind tunnel in the forest, kind of like a giant bee treadmill, and gave some wild bees a workout. She noticed that orchid bees, which have unusually large hind legs, use them in a funky way. She expected they would tuck their big legs up at high speeds, to reduce drag, but instead the bees let their legs dangle. That did produce drag, but it also tilted the bees' bodies nose-down, putting their wings at the angle they needed to fly really fast.
"This is basic research," Combes says. "I'm not building any miniature aircraft. But it's always surprising what can come out of basic research. In studying insect flight, people usually look at how the wings work--that's what they've been doing for years and years. They never really looked at the legs." Who knows? Someday a successful MAV may have insectlike wings and legs. One more field where scientists are turning to insects for inspiration is therapeutic drugs. You've probably heard of biological prospecting: looking for useful chemical compounds in rain forest plants or coral reef organisms. Well, there are four million species of insects out there, and they use all kinds of biologically active substances. Mosquitoes make proteins that keep blood from clotting. Fireflies make proteins that glow in the dark. Termite soldiers squirt a compound with antimicrobial properties.
So before you swat that mosquito, remember that someday, after a tiny wasp makes your diagnosis, some other insect may cure your ailment. And it won't even expect you to say thank you.
While Pennsylvania writer Cynthia Berger was studying for her Master's degree in insect behavioral ecology, her mother's friends would send her bulging envelopes stuffed with bugs "just because they thought I'd like to have them," she says.
The Latest Buzz on Bugs
Scientists continue to uncover surprising new facts about insects' amazing abilities and behavior. Here are three of the latest discoveries:
British scientists caused a stir this year when they announced in a paper that they had discovered the first example of non-human teaching, and the teachers and pupils were … ants. The scientists witnessed Temnothorax albipennis ants leading others to a food supply. Because the leaders slowed down to offer direction, the study's authors claimed that their behavior fits the animal behaviorist definition of teaching: modifying their actions, at cost to themselves, in order to help other individuals to learn more quickly.
What looks to us like a plague of locusts is really just a matter of safety in numbers. Researchers working in Utah and Colorado recently confirmed that by attaching tiny transmitters to the backs of Mormon crickets, which travel in groups of millions, and separating a number of them from the pack. More than half of the tagged stragglers were eaten by predators, compared to none of the crickets that remained with the pack--proof that when you're a cricket, it pays to hang with the crowd.
Got a lazy housemate? Maybe you could try doing as wasps do. A Washington researcher found that when worker Polybia occidentalis wasps notice their nest mates hanging around the nest instead of foraging for food, they bite the slackers. Sometimes one nibble isn't enough; some insects were bitten several times over many hours before they got the message and left the nest.
Nature Watch: A Bee's-Eye View
Ever wonder how hungry bees choose a flower for feeding? It turns out that they are following invisible (to us) clues. Bees have faceted, compound eyes that are sensitive to ultraviolet (UV) rays--rays that are normally filtered out by the lens in the human eye. And many flowers have UV patterns that work like billboards to attract passing bees. One of the most dramatic examples of UV coloration in flowers is this silverweed, Potentilla anserine. The plant's blooms look uniformly yellow to the human eye but appear to bees as distinct bull's-eyes. The center of the target pattern is where pollinators find nectar and pick up the pollen that helps the flowers to reproduce. Norwegian nature photographer Bjorn Rorslett uses UV-sensitive equipment to photograph flowers as bees perceive them.
Missing: Bees and Flowers
Which came first: bees or the flowers they pollinate? Or, more to the point, which will disappear first? A new study by scientists from the Netherlands and Great Britain finds that the diversity of wild bees and the flowers they feed upon and pollinate has dropped significantly in both countries over the last 25 years.
In Britain, for example, a drop in bee diversity in the last few decades has been accompanied by declines in 70 percent of the wildflowers that are pollinated by insects. Plants that are either wind-pollinated or self-pollinated, on the other hand, have held steady. The researchers say that while the populations of some other pollinators--hoverflies, for one--have actually been increasing, this doesn't mean that those other insects can make up for the missing bees. The bees tend to be specialists: They stick to a limited range of flowers that generalists such as hoverflies might ignore.
The worldwide economic value of the pollination provided by wild bees is estimated to be more than $20 billion annually, according to researchers, so a decline in bee diversity could have devastating economic and environmental consequences. --Hannah Schardt