Honey bees are highly valued in part because they are essential players in the maintenance of industrialized agriculture (almonds, canola, and cherries, for instance). They are also important for our sustenance in a variety of other, less obvious ways. In the 1990s, when I was involved in a research project on Brazil nuts, I discovered that before these nuts became fodder for cookies and muffins, they were part of a complex tale, one that involved bees, trees, birds, and rodents working together to bring them to fruition.
The Brazil nut tree (Bertholletia excelsa) grows in mature forests of the Amazon, only reaching reproductive age after thirty years, and can live as long as 1,600 years. During those years, the castaña, as it is called in Spanish, can grow to fifty meters tall, spreading its branches to thirty meters in diameter. Brazil nut forests only occur in the southwestern arc of the Amazon region, in an area that encompasses parts of Brazil, Peru, and Bolivia. The peak flowering of the castaña is in October, November, and December. During this time, in a daily cycle, the trees produce large flowers that fall to the forest floor.
The crown of the castaña provides a space for wild Stanhopea and Catasetum orchids, which, like all orchids, are epiphytes (plants that grow harmlessly on other plants). They need a place to hang out, gathering water and nutrients from the air and the surface of the tree. These orchids attract the orchid bees, especially the romantic vagabond males looking for the right cologne and the right female. Male orchid bees, with their large bodies and big tongues, are one of the few insects capable of penetrating the large and heavy outer petals of the Brazil nut flower to pollinate it. So, while they are hanging around the pretty orchids, pollinating them and picking up a female-attractant, they also visit the castaña flowers.
As the Brazil nut pod matures on the tree, macaws feed on the fruit, thereby lightening the load of the branches and protecting them from breaking due to excessive weight. The tough-skinned two-kilogram pod, when ripe, crashes to the ground, where it is collected by the brown agouti (Dasyprocta variegate), a large rodent that is the Brazil nut tree’s main seed disperser. The agouti cuts through the pod’s hard shell to get to the nuts, and those it does not eat, it buries for later consumption. Of course, the agouti doesn’t always remember where he left his nuts. Those are the ones that, over decades, can replenish the forest. The next time you crunch into a cookie with Brazil nuts, think about bees, orchids, and the rain forest.
Among the lessons entomophagists will need to heed again and again as insect-eating expands geographically are that the insects we care about (whether as plagues or as food, or, in the case of butterflies, for their beauty) may be vulnerable in unexpected ways. Thinking laterally — as from Brazil nuts to orchids to bees — is essential if we are to even begin to understand the ways in which humans and the millions of mostly unknown insects influence each other.
The Brazil nut case is but one illustration of how little we understand the “languages” used by insects, which we will need to learn if we are to more deftly manage our entomophagical relationships with them. For other livestock, understanding the meaning of their behaviors, the sounds they make, and the chemical signals they give off have had important implications for breeding, selecting for desirable traits, and diagnosing illnesses. How, then, do insects communicate?
Many insect predators, including people, are familiar with the stinging chemical warning shouts and bites of hornets, bees, and ants. Entomologist Justin Schmidt, sometimes called the “Connoisseur of Pain,” has documented and rated many of these using a pain-measurement scale. To focus on these toxic stinging and biting forms of cross-species communication, however, would be like lumping the spears and gunshots fired by people — which of course bear their own meanings — together with the complex subtleties of spoken and body languages. One of our late learnings with regard to managing cattle is the relationship between hormonal cycles, milk production, reproduction, vocalization, and behavior around other cattle. For insects, the counterpart to hormones is pheromones.
Jean-Henri Fabre was a nineteenth-century French naturalist and the author of ten volumes of Souvenirs entomologiques. Derided by “serious” scientists because he wrote so that non-scientists could understand, today he is best known, and widely celebrated, in Japan. An anti-evolutionist, he was nevertheless praised by Darwin for his careful and keen observations, particularly on insects. In 1874, Fabre noted that a newly emerged female peacock moth, stretching her wings under a wire-gauze bell jar, was attracting males from very far away. This observation led to the identification of so-called “calling glands” in insects. Over the next century, the chemicals released from these glands came to be called pheromones. One of these perfumes, released by the female Indian luna moth, could be detected by males over ten kilometers away. Insects release pheromones that are like specialized dating sites, enabling them to find members of their own species. Some are designed for long-distance seduction. Others, released by males, act over shorter distances and are termed aphrodisiacs, which May Berenbaum describes as “excitants — something to put the female in the mood.”48 There are even “hey boy, back off!” pheromones, such as the “mace” squirted at persistent males by an already-mated female Pterostichus lucublandus. There are alarm pheromones, pheromones that synchronize group activities, those that protect areas where eggs have been laid, and those that serve as trails to food supplies.
We have already encountered the link between the scents of orchids hanging out on Brazil nut trees and the bees that pollinate the trees. Orchids might be seductively pretty, but they are also devious. The orchid Dendrobium sinense, endemic to the Chinese island Hainan, is pollinated by the hornet Vespa bicolor. The flowers’ challenging problem is that the hornets prefer to catch honey bees and feed them to their babies; they’re not much interested in pretty flowers. So the orchids produce a chemical component of the alarm pheromones of both Asian (Apis cerana) and European (Apis mellifera) honey bees. The scent of the flower, mixed with the alarm pheromone, attracts the hornets, who pollinate the flowers while hunting the bees.
This brings to (my) mind the beekeeper anecdotes about bananas and bees. The scent of bananas also mimics the alarm pheromones of honey bees. Since banana flowers in the wild are pollinated by bats and birds, is this scent a way of bringing in bees so that the pollinators are attracted by the scent of a bee lunch?
I am reminded of the time I accompanied my son Matthew, who owns and operates Unspun Honey in Mt. Gambier, Australia,49 when he was called to remove a swarm that had reportedly settled into a black commercial compost barrel in someone’s backyard. A swarm, which is a homeless colony of bees with a queen scouting for a new place to live, is generally not aggressive. They don’t have a home to protect and are busy negotiating with scouts about new possibilities. We carefully approached the buzzing composter across the small backyard, stepping over children’s toys. Matt lifted the lid and looked in. This was not a swarm. These bees had already decided that the composter was a cozy suburban home — protected from the weather, near flowers — and had started to build comb on the underside of the lid. When Matt began to scoop the bees into his pail, they became irate and began to attack him. He went back to the truck and returned with a hive box, into which he had put a “lure” — lemongrass, which mimics a bee pheromone that says “this is a good home.” He dumped in as many bees as he could, including the queen, and then left the box there, propped on the edge of the composter bin, for the day. When he returned that evening, much to his and the homeowner’s relief, the bees had all settled into their new, lemongrass-scented home, and the compost bin was empty. While orchids and banana plants may be able to mimic the bee alarm pheromone, lemongrass makes them feel at home.
Pheromones provide potent ways for insects to communicate and are therefore important to consider as we develop insect management and farming practices. But pheromones are not the only insect languages. Like people, insects also learn about their surroundings through visual an
d aural cues and send messages through the sounds they make. The nature of these messages among insects, however — how they are sent and received — often differs qualitatively from what we have come to consider normal through observing other species, including our own.
“Listen,” said Matt to me as we paused amid the sunny buzz of bees whizzing over our shoulders, to and from the hives. “You can hear that the hive is happy.” I listened, and thought of Mark Winston’s assertion in his 2014 book Bee Time, that “a tacit understanding exists between beekeeper and colony; if you’re calm around honey bees, they will be calm as well, creating a dynamic that feels to the beekeeper like a relationship.”50 When I first started thinking about insects and sounds, my thoughts went to the soothing or angry sounds of Matthew’s bees, and then to chirps and trills of male breeding-age bush crickets (katydids) and to the cheerful chirping of eager crickets that I’d heard in small household breeding pens in rural Lao PDR and the warehouse-sized Entomo barn in Canada. The male crickets chirp that they are ready now; where are the females? We haven’t much time! For the forager or farmer of insects, these chants, trills, and songs are important signals, messages from the insects to those who aspire to manage them.
Non-insect-eating urbanites, especially those of us who grew up listening to rock ’n’ roll and working in factories without safety protection earmuffs, are most attuned to very loud sounds. The loudest sound produced by any animal on the planet, on a body-weight basis, comes from the tiny lesser water boatman (Micronecta scholtzi), who can generate ninety decibels by rubbing his penis against his abdomen. Eggs from another member of this family, the axayacatl water bug, were sold by the Aztecs; the Spaniards called it Mexican caviar.
While I have not heard the water bugs or tasted their caviar, I have had my ears punished by the heavy-metal shrieking of the East Coast brood of the genus Magicicada. These animals, celebrated, eaten at opportunistically celebratory banquets, and despised as a bug plague, emerge dramatically and with predictable periodicity from the soil. The broods, which are staggered so they don’t all come out dancing across the United States at the same time, are labeled by Roman numerals. For these periodical cicadas, found only in North America, the number of years between one emergence and the next is always one of two prime numbers — thirteen or seventeen — a phenomenon that no one has yet explained in any convincing manner. Just before the big bio-dance, the nymphs burrow up to just below the surface, ready to enter the stage all at once. When the temperature and moisture are just right, they emerge by the millions and millions, crawl up the nearby trees, shed their skins, and have a coming out party. For any animal that eats bugs — fish, small mammals, turtles, birds, and people — the cicada emergence is a once-in-a-lifetime belly-stuffing bonanza. The soft, white adults harden and darken within hours and then fly clumsily about, the males singing boisterously. This time in the lives of the Magicicada is described by musician-philosopher-naturalist David Rothenberg (in his book Bug Music) as a “few weeks [of] nothing but revelry, music, and sex.”51 About ten days later, they mate, and then, as seems to happen after all such parties, the fun is over. The females deposit about 500 eggs each in slits they make in the tree bark. Six or seven weeks later, by which time the adults are dead, the little nymphs hatch, drop to the ground, and dig in for some prime years of resting, nibbling roots, and sucking phloem. When the adults die, their bodies become a huge dose of fertilizer for the elm, maple, oak, and ash trees they prefer. Quite apart from the noise they make, the periodical cicadas are important long-term recyclers of nutrients in the deciduous forests.
Much of the ecological soundscape of insects is, however, much quieter, not intended for human ears — especially not for those of us with eardrums damaged by rock ’n’ roll and industrial work.
In 1977, Canadian composer, teacher, and musician R. Murray Schafer published The Tuning of the World, in which he invented what has come to be called — in research journals and books — acoustic ecology. Schafer has argued that we pay too much attention to the loud noises, the birds and crickets; as a result, we miss the complex, subtle communication systems among a variety of insects and plants. In 1992, musician and composer David Dunn released Chaos and the Emergent Mind of the Pond, a recording (and rearranging) of the rhythmic clicks and pops and buzzes of aquatic insects in North American and African ponds. Almost fifteen years later, he released The Sound of Light in Trees: The Acoustic Ecology of Pinyon Pines. Using tiny microphones and transducers placed in the phloem and cambium of pinion trees of the southwestern United States (Pinus edulis), he recorded the “voices” of, and conversations among, pinion engraver beetles (Ips confusus) and, possibly, bark beetles (Dendroctonus), as well as larvae of various wood-boring and longhorn beetles. He and his colleagues compared infested trees with healthy trees and proposed that what they called “bioacoustic interactions between insects and trees” were “key drivers of infestation population dynamics and the resulting wide-scale deforestation.”52
In 2015, a team of Spanish researchers reported on a study they had done on two tiny mirid bugs, Macrolophus pygmaeus and Macrolophus costalis, which feed on aphids, whiteflies, and other pests of vegetable crops. Using “laser vibrometry” (which is not, apparently, a sex toy), they measured what they called “substrate borne” vibrational signals. What they discovered was that these minute bugs used communications built around two distinct sound types, each with its own harmonic structure. The first, a “yelp” sound, is the basis for an important pre-mating song. The other seemed to be associated with an increase in the time the bugs spent walking.
With the exception of blind people, most of us rely on sight to orient ourselves in space, and we often assume that our visual world is similar to those of insects. We know, however, that bees are “red-blind.” Like humans, bees have three photosensitive pigments, but they encompass the ultraviolet blue-green range; that is, they are sensitive to ultraviolet wavelengths, below 380 nanometers, which we cannot see. We have blue-green-red receptors, but the bees see only black where we see red. Dragonflies and butterflies, on the other hand, may be pentachromatic. It is difficult to imagine what the world looks like if one has five built-in color channels.
Of course, vision is not just about distinguishing colors. Flowers that are viewed through an ultraviolet filter such as those of the bees probably look quite different than they do in what we consider “normal” light; some, like black-eyed Susans, apparently have a bull’s-eye pattern to attract pollinators; others have what looks like a runway to guide insects into landing. Further distancing their visual worlds from ours is the fact that many insects that go about their lives in daylight have compound eyes with multiple, independent light-gathering units, called ommatidia. Inputs from the ommatidia are brought together in the brain, where a single upright image is created. This is called an apposition eye.
Fireflies, moths, and many insects that fly at dusk or in the dark have what are called superposition eyes, which are 100 times more light-sensitive than the appositional eyes of diurnal insects. In superposition eyes, the ommatidia cooperate and only project one image back onto the retina. When our family lived in Java, I would sometimes go out into the darkened countryside to look up at the stars in the clear heavens, unpolluted by the haze of city lights; looking across the dark, flooded rice paddy, I was awed by the shimmering sheets of fireflies (actually beetles of the Lampyridae family), their lights flashing on and off in synchronous waves. What I did not understand at the time was that I was seeing mate-seeking male fireflies flashing species-specific light messages; females of the same species would respond with their own unique light, sending a message: “Here I am, ready, willing, and just waiting for you!”
Being able to send, interpret, and receive appropriate light signals among a cacophony of signals from similar species is, for these beetles, a matter of survival. Unfortunately for Photinus males, the related but different Photuris females have figured out the code of seve
ral other species, including Photinus. When the Photinus males respond eagerly to the come-hither signals, the Photuris females eat them. I guess it’s one way to eliminate the competition and have a good meal at the same time.
Neither the apposition bees’ eyes nor the superposition fireflies’ eyes have the ability to focus, nor can they move in their sockets. They are, however, much quicker and more efficient at detecting motion than our eyes are, which is why insects are so difficult to catch, and which has implications for those who wish to create foraging techniques that don’t involve excessive collateral damage.
Ball-rolling dung beetles, which are eaten in many parts of the world, use patterns of light polarization and visual cues from sunlight, stars, and, more specifically, constellations such as the Milky Way. Diurnal beetles, which are active during the day, have compass neurons that respond to sunlight. The neurons in the brains of nocturnal beetles can also respond to polarized light from the moon, and light cues that are a million times dimmer than those that guide the day-shift workers. The beetles need to move in a straight line away from the dung pile in order to avoid competitors and thieves; before they start moving, they climb up on the dung ball and, dancing with the stars, orient themselves. Once they figure out where they are, and where they need to go, they begin to roll the ball, occasionally climbing up to dance again if they lose their way.
Eat the Beetles!: An Exploration into Our Conflicted Relationship with Insects Page 10
