Reviewed by Terril L. Shorb, Ph.D
Six Legs Walking: Notes from an Entomological Life
by Elizabeth Bernays
Raised Voices Press
$16.95, September 24, 2019, ISBN: 9781949259032
The centerpiece of the big oak dining table on our Montana ranch was unvarying: ceramic salt and pepper shakers shaped like ears of corn, ribbed-glass sugar dispenser, and a tall canister of Black Flag insect spray. So loathed were flies, ‘skeeters’ and other UFB’s (unidentified flying biters), we kids cheered when mist from the spray drifted like gentle rain onto our table and food. Little has changed from those days in terms of the gusto with which people try to eliminate bugs. Overall, pest control in America today is a $14 billion dollar industry.
Some fear and loathing is not without reason, of course. Insects can and do cause significant damage to food and health. But history records a vast and indiscriminate war against insects caused harm in itself, particularly with the new and deadly arsenal of chemicals generated by World War Two. By the early 1960s, Rachel Carson sounded her famous warning against DDT and other toxins as principle destroyers of bird life, including near extinction of the nation’s living symbol, the Bald Eagle. DDT was banned and the eagle recovered. However, efforts to kill insects and other pests continues with risky fervor. Homeowner attempts at DIY pest control racked up about 81,500 pesticide exposures in 2016, according to poison control centers across the United States.
Bugs, of course, are not all bad. Louisiana State University entomologist Timothy Schowalter says insects also are important to our nation’s pharmacopeia, providing compounds such as “cantharidin (from blister beetles) for wart removal, alloferon (from blow fly larvae), a powerful antimicrobial compound, and, promising anti-cancer compounds from wasp venom.” The news for bug themselves, though, is not so good. Habitat loss, pollutants, invasive species, and climate change are combining in ways that could eradicate 40 percent of insect species within a few decades. That’s frightening news for insect eaters such as birds. Or for farmers who depend upon insects to pollinate their crops. Regardless of our personal views of them, insects are hugely important to all life on earth.
All that signals good timing for a new book, Six Legs Walking, by entomologist Elizabeth ‘Liz’ Bernays. Few scientists have had more direct field experience with insects than Liz Bernays, who spins an engrossing tale of small critters few of us ponder beyond the sheen of repellent we apply to our skins. Hers is a personal story that reveals glimpses into the lives of six-leggers through field biology borne of close observation and innovative experiments with members of the class Insecta, some of whom, it turns out, are good learners.
Liz’ fascination began when she was a nine-year old girl in Queensland, Australia. “They grab my attention with big green wings, delicate shining membranes, black horns, clubbed feelers, jeweled torpedo bodies, feathery textures, lights blinking in the night.” By age eleven she is feeding captive silkworm caterpillars mulberry leaves until they cocoon. She then plunks the pale bundles into boiling water, and, with aid from a modified cotton reel, spins silk. That inventiveness becomes a hallmark of the young entomologist’s career.
Her mother supports her bug-centered life and buys her a butterfly net. Miss Gray, a teacher, encourages her to collect and categorize specimens which Liz sends to the National Museum of Australia in Canberra. Many are new to science, accomplishments that earn18-year-old Elizabeth a scholarship to University, first in her family to do so. Her Mother derives vicarious pleasure from her daughter’s success, Liz writes: “She married my father only to please her parents who would not accept the man she really loved…when I was nine, the attraction of flowers and insects was comfort against my sadness, which was somehow related to Mama’s sadness.”
Liz completes a Master of Science at Birkbeck College and one of her teachers is Dr. Reg Chapman, of the University of London. Before long, she and Reg experience a “summer of love among the grasshoppers.”
Early in her career she worked as a British aid scientist and she and Reg were available to Indian insect and plant biologists at ICRISAT (International Crops Research Institute for the Semi-Arid Tropics) at Hyderabad, India. Immediately she was absorbed into a challenge of reducing herbivory on sorghum, a hugely important food crop for a people among the poorest on earth. She observed the mother moth lay her eggs near the bottom of the plant, subjecting the new caterpillars to an arduous climb to the plant’s crown where they could forage on leaves tender enough for their tiny jaws. The reason, Liz learned, was eggs deposited higher on the plants were parasitized. Further close scrutiny found some of the adolescent caterpillars were disoriented at their summit destination, wandering atop leaves until they were blown off by the wind. Here might be a clue to the plant’s defenses.
Liz made exact replicas of the sorghum plants from jeweler’s resin and took the casts outsider at dawn which was climbing time for the caterpillars. She coated her fake plants with wax from sorghum leaves on resistant plants and found the substance confused the little ‘pillars who froze atop upper leaves until they fell off or were carried away. She reasoned the leaf wax contained chemicals that confounded the tiny taste buds of the larvae. With her Indian counterparts Liz made extracts from resistant sorghum leaves, “dipped leaves in different solvents, separated fractions, purified precipitates….submitted samples for identification in gas or liquid chromatographs.” Eventually it was determined the proportion of the wax profile constituents was key and that “different levels of gene expression eventually turned out to be the answer.” Other researchers would follow the lead and study the “control of the chemistry of wax production,” a research pathway that would prove useful in helping plants reduce water loss and in interfering with behaviors of parasitic insects, also shrinking entry of fungal diseases.
Liz returned to Britain with the successes in the Hyderabad laboratory much in mind to continue pursuit of genetic codes of sorghum diseases and insect predation. And she retained a love for the exotic amalgam of cultures that was India and her “memory of tiny caterpillars in the early mornings when dew was on the leaves and mist hovered over the old mosque at Pateancheru.”
Later, settled in Tucson, Arizona, Liz attunes her antenna of interest to a species of horse lubber grasshopper that’s mouse-size and glossy black. She asks why such plant-feeding insects “march about eating so many different things? And, by what process do they make a decision to switch to a new food?” Ten-hour days under the broiling Sonoran sun, coupled with lab work, nourishes insight that shimmer provocatively as heat waves. She realizes lubbers are drawn to poisonous plants, passing up milder grasses and wild lettuce. The salad bar of poison, it turns out, precludes the likelihood of one species’ chemical toxins reaching a dangerous dose. Liz notes that “if attacked, the (Lubbers) lift their black and green front wings, flash their read back wings, buzz, and exude an ill-smelling, frothy, poisonous mixture.” Predators who ignore the dramatic show and try to gobble lubber snacks end up spitting them out, scrupulously eliminating horse lubbers from future dining plans.
Liz presses on in her sweaty observations, determined to answer the second question about the mechanism the hoppers use to make menu choices. Her lab work demonstrated lubbers will munch on a plant doctored to taste like, say vanilla. But only for a while. If offered another round of the same flavor, it’s rejected. If the same plant-base is doctored to taste like peppermint, the lubber eagerly chomps a few bites and moves on. She confirmed that for the lubber, variety is a life-saving strategy, assuring a ready supply of fresh and ever-changing toxins to discourage larger creatures making a meal of it.
A fan of novelty, Liz delighted to find lubbers exhibiting preferences for new dietary options, something that also can be witnessed in the “novelty-induced locomotion in rats…a gene for risk taking in humans…rover versus sitter behaviors in fruit flies…or shy versus bold behavior in sunfish.” She acknowledges that her feeling of “closeness to lubber grasshoppers is not, perhaps, crazy…the fact that I share behavioral characteristics with individuals of other species, and such different ones at that, gives me the profoundest sense of belonging in the world.”
Not shy about bucking convention, she was drawn to study of Manduca sexta, the Hawk Moth. “Biologists had been arguing about the relative importance of the food plant versus predators and parasites in determining the affiliation of a plant-eating insect with a particular plant host(s). Plant-eating insects and their hosts make up 50 percent of all species of life (excluding bacteria and viruses) and most of these insect species specialize on just one or a few types of plants. Why? I turned over the ideas…for years. Having the time for reflection during observation is another element in the joy of observational research, stewing together curiosity, known facts, conventions and hypotheses, possibilities and doubts until new connections arise and eureka moments emerge.”
One widely held notion in entomology was insects and host plants engaged in a form of chemical co-evolution, plants evolving new toxins to defer insects even as insects evolved ways to circumvent the defenses. Liz wondered about this, noticing that plant defenses may not poison the insect but merely make plant tissues unpalatable. Were there other reasons an insect avoided a plant? Perhaps it was simply more vulnerable to predators when it foraged there. She began to observe the triad of players–plants, herbivores, and the insects natural enemies–through their tritrophic interactions. Given her previous observation of the 100 percent mortality rate of hawk moth offspring, what else might be involved? Liz observed a moth mama lay her eggs on a neighboring devil’s claw plant and yet another deposit eggs on both devil’s claw and datura. Further scrutiny revealed moth eggs laid on devil’s claw had a higher survival rate. Further, sticky leaves of devil’s claw proved hazardous to ants, lacewings, and other parasites who would have preyed on moth eggs. Why, Liz mused, wouldn’t Manduca moth mamas switch for good to devil’s claw? It turned out there are two generations of Manduca each year and the host plant, datura, is available in spring and summer months while devil’s claw matures only after summer rains in August. “Female moths need to stay with datura, but in the wet summer months, they must include devil’s claw in their repertoire of hosts to enhance the numbers of surviving offspring.” Liz writes that such persistent observation “can become complex with study, similar to Darwin’s tangled bank. But above all for me was the thrill of finding out how something works–an excitement with me still.”
Another insect conundrum beckoned. Among insects, as among many other species, there are specialists and generalists. Do strategies of specialists who forage on a single species of host plant convey greater probability for survival because they risk less exposure? Liz dreamed up another ingenious experiment that involved teaching groups of grasshoppers, Schistocera americana, either to feed on a single food type or on a mix of a half dozen types of host food-plants. On ‘test’ day, those educated as specialists moved faster and more directly to their host plant. They were “more efficient than the generalists and foraged for a shorter time to eat the same amount–a good thing for reducing mortality.” Results were confirmed with other species of insect specialists such as white flies, moths, and beetles who discovered the best food quicker, hesitated less in foraging, and proved more quickly for the favored plant sap. They also were more vigilant in monitoring other factors around them as they fed. Liz writes, “(E)arly emphasis on insect-plant co-evolution has to give way to a more comprehensive story involving at least three factors: the plant, the herbivore, and a variety of enemies of the herbivore…The risk of death is so high for the herbivores, it is a major selective force in their host affiliation. The importance of selective attention and vigilance, so well-studied in humans and other vertebrates, is no less important in insects. It is reason enough to expect specialists to predominate, allowing later evolution of refinements such as exceptional camouflage.”
These days, Liz looks out over her Tucson garden and sees plastic cups now used to keep birds from dining on tender garden veggies. The cups are relics of former experiments involving feeding habits of locusts which showed patterns evident within all locust feeding activity and in individualistic behavior. One locust under observation, number nine, “always rested on its back with legs in the air.” The researchers thought at first number nine was ill, but it remained healthy, ate well, and was not sick but only different. “I tell students about number nine to impress on them that, like all other animals, insects are individualistic.”
Those cups also are emblems of sweet memories with Reg, her late research partner and life mate. The cups, she recalls, were a small part of “my entomological life, yet they engender intense nostalgia. I reflect on the meaning of that mixture of longing, love, and melancholy and all the days of working with a soulmate. I reflect with contentment on the small part I played in the bumpy progress of knowledge and concede the possibility that, just as most of the players are, I will be forgotten as the years pass. We are tiny points of light, like a mass of glowworms in a cave, each living briefly and passing on, but wonderful at the time.”
Six Legs Walking is a tribute to a time-honored but sadly vanishing tradition of vigorous biology conducted principally in the habitats where creatures live. Many of this reviewer’s environmental studies students figure their future depends upon mastering the science of genetics and what an elder field biologist friend dismissively refers to as “blender science.” This book is a helpful antidote to that kind of lop-sided preparation. It also is quiet testimony to the genius of Elizabeth Bernays’ peculiar species of inquiry which often furrowed the brows of convention-bound scientists. I will recommend this book to my science students and all others who wish to figure out what nature is up to out there. Such patient observation inspires otherwise hidden insights we will require to track vast and intricate changes in our biophysical world. And successfully adapt to them. Elizabeth Bernays thus shares with us more than six reasons to pay attention to the creepy crawlies that inhabit our households and dreams. Six Legs Walking is a wonderfully told tale that recalls the golden era of field biology whose time, I fervently hope, has come again.
About the reviewer: Terril L. Shorb is a teacher of environmental studies and sustainability at Prescott College and co-founder with his wife, Yvette A. Schnoeker-Shorb, of Native West Press, whose books celebrate natural history of wildlife in the American West. His writing on the natural world have appeared recently in publications such as The MacGuffin, Kudzu House, QU Literary Journal, Cargo Literary Magazine, bioStories, and Green Teacher Magazine.