The familiar teardrop eggplant, with its deep purple luster, is but one member of a large and diverse botanical family. Some eggplants are long, lean and pendulous, like smooth-skinned cucumbers. From a distance, ripening kumba eggplants are indistinguishable from miniature pumpkins. And oblong white cultivars that look like they were plucked from beneath chickens and ostriches explain the etymology of “eggplant."
Nowhere is the entire spectrum of eggplant shapes and colors more apparent or celebrated than India—the vegetable's birthplace and its second-largest producer worldwide. India grows more than a dozen cultivars of eggplant—or brinjals, as they are known locally—and is home to many wild eggplant relatives as well. Equally multifarious diseases and pests routinely ravage this abundance, but one does more damage than any other. Every year Indian farmers lose around half of their crops to the eggplant fruit and shoot borer—a moth whose larvae eat their way through brinjals in Africa and Asia. In really bad years the larvae may destroy 90 percent of crops.
To combat this vermin, farmers in India slather brinjals in organophosphates and other chemical pesticides that are known to linger in the environment, kill all kinds of beneficial insects and make people sick even at low doses—the kinds of chemicals the U.S. and many other developed countries have banned or restricted. Such applications are often ineffective because the larvae remain concealed and protected within the eggplant itself. Any surviving brinjals are coated with a thick white film of insecticide residue as much as 500 times the maximum permissible level. "The amount of pesticides sprayed on brinjal, cauliflower and cabbage is amazing—frightening," says P. Ananda Kumar, director of the Institute of Biotechnology at Acharya N.G. Ranga Agricultural University in Hyderabad, India. "If you saw it you would you never ever touch a vegetable in India."
Starting in the mid 1990s, Kumar and other scientists working for both universities and biotechnology companies in India—including Mahyco, a seed company partially owned by Monsanto—began devising a way to deter the fruit and shoot borer and dramatically increase eggplant yields without using so many noxious insecticides. They would still rely on a toxin to kill the larvae, but instead of synthetic chemicals they would use poisonous proteins produced by a common soil bacterium called Bacillus thuringiensis (Bt)—toxins organic farmers had safely used as a form of biological pesticide since the 1920s. Rather than formulating a spray or powder, though, the researchers were going to borrow the bacterium’s toxin-making gene and insert it into the eggplant’s DNA so the plant could produce Bt toxin on its own. The resulting Bt eggplants would kill only the fruit and shoot borer and possibly closely related species, leaving other insects and creatures unharmed.
Mahyco succeeded in creating Bt eggplant seeds and, in collaboration with Cornell University and the U.S. Agency for International Development, gave them to several Indian universities, where researchers began to breed them with local brinjal varieties. The plan was to sell the insect-resistant offspring to rural farmers for very little money or dispense them for free. By 2009 different teams of scientists had produced several types of Bt brinjals and extensively tested them to make sure they were not poisonous to people or animals and that wild eggplant relatives would not become less diverse or too unruly if they exchanged pollen with genetically modified (GM) strains. In October 2009, based on the recommendations of expert committees, the Indian government approved Bt brinjal for commercialization.
But Indian Environment and Forests Minister Jairam Ramesh intervened. Thousands of angry and alarming faxes and e-mails from Greenpeace and other anti-GM organizations flooded Ramesh’s office. Several scientists known to oppose genetic modification urged Ramesh to ban Bt brinjal. And farmers riled up by the opposition protested in the streets. Opponents argued that, despite the safety testing—and despite the fact that farmers in India had grown Bt cotton since 2002 with great success—Bt brinjals endangered people's health and the environment. In February 2009 Ramesh imposed a moratorium on the release of Bt brinjals until India arrived at a "political, scientific and societal consensus" about their safety and benefits.
What many consider a disastrous imbroglio continues to stew in India. "Most of the concerns raised are devoid of any logic and not based on any proper scientific analysis," Kumar says. "Science has taken a backseat to politics." Elsewhere, after nearly 20 years of growing Bt corn, cotton and soybeans around the world and almost 100 years of using Bt sprays, researchers have reached a consensus about many of Bt’s advantages and risks. At this point, the evidence overwhelmingly demonstrates that Bt toxins are some of the safest and most selective insecticides ever used. Claims that Bt crops poison people are simply not true. When properly managed, Bt crops increase yields and make croplands far friendlier for insect populations as a whole by reducing the use of broad-spectrum chemical insecticides that kill indiscriminately. Fewer chemical sprays also translate to cleaner grains, legumes and vegetables mixed into processed foods and sold whole in the produce aisle.
Bt crops are not entirely benign, however, nor are they a panacea. Despite the unparalleled specificity of Bt toxins, recent studies indicate that in a few rare cases they may inadvertently kill butterflies, ladybugs and other harmless or helpful insects, although so far there is no solid evidence that they poison bees. Even more concerning, agricultural pests can, will and have become resistant to Bt crops, just as they inevitably develop immunity to any form of pest control. If biotech companies prematurely release new Bt varieties without proper testing or farmers do not take adequate precautions when growing them, Bt crops ultimately fail and, ironically, encourage the use of chemical pesticides they were meant to replace. Most recently, some farmers in the Midwestern U.S. have realized that one kind of Bt corn no longer repels voracious root-chomping beetle larvae.
“Genetic engineering can be a powerful tool and provide opportunities for managing insects we have never had before, potentially with far less harmful environmental impact and certainly less threat to human health,” says entomologist Kenneth Ostlie of the University of Minnesota. “The true challenge is good stewardship.”
Serendipity in the soil
B. thuringiensis is a ubiquitous bacterium that lives primarily in the soil as well as in water, on plants and in grain silos. In times of stress—when nutrition is scarce, for example—B. thuringiensis forms an endospore: a resilient, dehydrated version of its former self. Such spores are seriously durable, especially when protected from the elements; one group of scientists managed to revive 250-million-year-old Bacillus spores embedded in salt. During the sporulation process, the microbe also produces a diamond-shaped crystal packed with poisonous proteins known as cry toxins. The evolutionary advantage of these crystals remains something of a mystery, but they seem to help the bacteria infect various insects and continue their reproductive cycle within the bugs’ bodies. In fact, B. thuringiensis conducts most its conjugal activity inside the larvae of moths, beetles, mosquitoes and other insects, rather than in the soil.
In the wild, caterpillars and other larva munching on a plant teeming with B. thuringiensis will ingest spores and toxic crystals. Juan Luis Jurat-Fuentes of University of Tennessee and other entomologists have spent years studying what happens next in detail. Once inside the alkaline environment of the insect’s intestines, the cry toxins in the crystal separate from one another, bind to proteins embedded in gut cells and create pores that burst the cells. The insect’s hemolymph—its equivalent of blood—flows into its intestine and its gut juices seep into its body cavity, which alters the overall pH and impels the spores to germinate. In turn, the reanimated spores release a concoction of chemicals that further predisposes the insect to infection. Within hours all the internal chemical chaos disrupts communication between neurons and paralyzes the insect. Several hours or days later—consumed by a severe infection of B. thuringiensis and other opportunistic bacteria—the insect dies and the microbes use its decaying tissues as energy for a frenzied orgy.
People have been manipulating B. thuringiensis for their own purposes for nearly 100 years. In 1901 Japanese scientist Shigetane Ishiwata discovered that a particular strain of bacteria was killing large numbers of silkworms. He named the bacterium Bacillus sotto. Ten years later, Ernst Berliner rediscovered this same species of bacteria on a dead moth in a flour mill in the German state Thuringia; he gave the species the name that stuck: Bacillus thuringiensis. An easily duplicated living creature that killed insect pests without endangering other animals or people was an incredibly serendipitous find. But no one it in the early 1900s could have foreseen the extent to which this microscopic organism would eventually transform agriculture around the world.
Farmers began to use Bt spores and crystals as a biological pesticide as early as the 1920s. France produced the first commercial Bt insecticide, Sporine, in 1938. And the U.S. started manufacturing such sprays in 1958. By 1977, scientists had identified 13 Bt subspecies that made different kinds of crystals, all toxic to different types of moth larvae. Soon enough researchers isolated Bt strains that specifically killed flies, mosquitoes and beetles. Scientists have now catalogued more than 80 subspecies of B. thuringiensis and more than 200 distinct cry toxins. In most cases each subspecies and the crystals it produces evolved to kill only one or two insect species, even within the same insect family. B. thuringiensis subspecies tolworthi, for example, easily slays fall armyworm caterpillars (Spodoptera frugiperda), but is not nearly as lethal to larvae of the oriental leafworm moth (Spodoptera litura), which is in the same genus (the taxonomic level just above species).
In the 1980s, as crop pests developed increasing resistance to synthetic pesticides, more and more growers turned to Bt, which became especially popular among organic famers. In addition to their selective lethality, the bacterial toxins degraded in sunlight and washed away in rain, rather than contaminating wild habitat and sources of drinking water. This transience was both appealing and problematic for farmers, however, forcing them to reapply Bt sprays as often as every three days. And Bt formulations contained more than just spores and crystals; they were also full of synthetic chemicals that helped the bacteria spread over and stick to plants. Some of those chemicals were known to poison rodents and other mammals. The rapidly advancing technology of genetic engineering promised a cleaner and more precise way to use Bt. If it worked, farmers would never have to spray Bt in liquid form again; in fact, they could spend far less time and money on typical pesticides in general.
Scientists have several sophisticated tools for modifying plant DNA. Often, they recruit a rather unique and almost uncannily convenient microbe known as agrobacterium tumefaciens, which evolved to inject genetic material into plants to aid infection. In 1987 Plant Genetic Systems in Belgium isolated a gene encoding a cry toxin from one subspecies of B. thuringiensis and used agrobacterium to insert it into the genome of embryonic tobacco plants, creating the very first Bt plant life. That was just the beginning. Biotech companies in several different countries continued to improve this technique. Less than 10 years later, in 1996, the U.S. commercialized Bt corn and cotton. Farmers across the country readily adopted Bt crops because of their obvious benefits. "There's no question that Bt allowed us to grow and harvest more corn," says David Linn of Correctionville, Iowa, who has been farming his whole life. He explains that, before working with Bt corn, he would painstakingly search his fields for the eggs of a pest known as corn borer, trying to figure out when to spray chemical pesticides; the chemicals kill the newly hatched larvae only during a short window of time before they tunnel into the corn and out of reach. He often lost as many as 30 bushels of corn per acre to borers. "Bt corn meant not driving through fields, not spraying toxic chemicals, not using up fuel," he says. "It makes things a whole lot simpler when Bt is in the corn."
As of 2013, 76 percent of the corn grown in the U.S. and 75 percent of the cotton are Bt varieties. In 1996, 1.7 million hectares of genetically engineered crops were grown worldwide (a single hectare is about the size of the grass lawn in the middle of a standard athletic track). By 2012, the number had increased to more than 170 million hectares, at least 58 million of which were plants that produce Bt toxin.
A taste of our own poison
Some opponents of Bt crops and genetic engineering in general contend that government scientists and researchers at universities have not conducted long-term studies, or any studies, on the health risks of GM foods—that such experiments simply do not exist. Even a cursory search of the research literature refutes these claims. The independent nonprofit educational organization Biology Fortified, Inc., hosts a growing online database of 600 GM plant safety studies. Manufacturers have tested every GM food on the U.S. market to make sure they are not toxic and do not cause allergies and began selling such foods only after the U.S. Food and Drug Administration reviewed and approved the results of those tests. It's in the manufacturers' best interest to do so: After all, if something goes wrong after a company markets a GM product, there will be serious legal and financial repercussions.