Doomsday of Insects

  I have been obsessed with insects since I was a child. I still remember that when I was five or six years old, I found some yellow and black herbivorous caterpillars on the school playground. I put them in an empty lunch box and took them home. Later, they became beautiful red and black moths. To this day, this is like magic to me, and I am completely fascinated.
  In order to study insects, I traveled all over the world, from the Patagonian desert to the New Zealand fjords to the forests of Bhutan. In Borneo, I have seen swarms of birdwing butterflies pecking on minerals on the banks of the river. I have also seen thousands of fireflies flashing simultaneously at night in the swamps of Thailand. In my garden in Sussex, grasshoppers compete for courtship, earwigs tend to larvae, ants suck the sap of aphids, and leaf-cutting wasps build nests.
  But the number of insects is decreasing, which scares me. It has been 50 years since I first collected caterpillars in the school playground. During this period, there were fewer and fewer butterflies, fewer and fewer bumblebees, and almost all the small lives involved in the movement of this world became fewer and fewer. These amazingly beautiful creatures disappeared one by one. Statistics on insects are not the same and may not be accurate, but compared to when I was five years old, the number of insects is likely to drop by more than 75%. More and more scientific evidence supports this view. Studies have shown that the number of monarch butterflies (monarch butterflies) in North America has fallen off a cliff, insects in German forests and grasslands have disappeared, and the range of activities of British bumblebees and hoverflies has shrunk sharply.
  In 1962, Rachel Carson warned readers in his book “Silent Spring” that human beings are causing serious damage to the planet we live on. If she sees the horrible situation, she must be even more sad. Dry grasslands, swamps, heather shrubs, and tropical rain forests where insects once inhabited were flattened, burned or used as farmland on a large scale. In particular, Carson wrote that the problem of pesticides and fertilizers is getting worse, and about 3 million tons of pesticides enter the global environment every year. Some of the new pesticides are thousands of times more toxic than Carson’s era. Pesticides are degraded in the soil, rivers are polluted by chemical substances, and they are full of sediment. The phenomenon of climate change, unknown in Carson’s time, is now further devastating our planet. These changes have all occurred in our time and are accelerating.

Left: Professor of Biology Dave Gulson mainly studies insect ecology and conservation. Right: A yellow-sleeved wasp is flying.

  Not many people seem to realize the seriousness of the problem. Insects are not only related to human life, but also to the survival of animals that feed on insects such as birds, fish, and frogs. Insects pollinate crops, decompose manure, leaves and animal carcasses, keep the soil healthy, and control the number of pests. The earth cannot lack insects.
  More and more people live in cities and have only seen flies, mosquitoes and cockroaches since they were young. Therefore, most people don’t like insects, and many people are even afraid of them. Insects are often referred to as “horrible reptiles” or “bugs”. They are filthy crawling creatures that are offensive and spread diseases. Therefore, few people know how important insects are to human survival, and even fewer people think they are beautiful, intelligent, charming, mysterious and wonderful.
| An indispensable member |

  Insects have a long history. 500 million years ago, their ancestors began to evolve in the ancient ooze on the seabed. In the species we know, insects occupy a high proportion, and the number of ants alone is 1 million times the number of humans. If many insects die out, the biodiversity of the earth will decline drastically. In addition, due to the large number and variety of insects, they are closely involved in all food chains on land and in freshwater. For example, caterpillars, aphids, rock moth larvae, and grasshoppers are herbivores that convert plants into insect proteins that are more digestible and absorbed by larger animals. Insects such as wasps, carabies, and praying mantises are located higher in the food chain-they prey on herbivores. All the aforementioned insects are prey of reptiles, amphibians, small mammals, birds and fish. If there were no insects, these animals would have no food rations, and the herons, sparrowhawks, and ospreys that prey on frogs, shrews, starlings, and salmon at the top of the food chain would also go hungry.
  If insects disappear from the food chain, it will not only affect wild animals, but also human food. Most Europeans and North Americans feel uncomfortable when they think of eating insects, but it is strange that we enjoy shrimp meat (shrimp and insects are basically arthropods with exoskeletons). Our ancestors must have eaten insects, and from a global perspective, eating insects is normal. About 80% of the world’s population has the habit of eating insects, especially the indigenous peoples of South America, Africa, Asia and Oceania. Although Western society does not eat insects, we are often only one step away from them in the food chain. Trout and salmon eat a lot of insects, as do mountain partridges, pheasants and turkeys.

  From a global perspective, eating insects is normal.

  Therefore, we can think that humans should raise insects in addition to pigs, cows, and chickens. Farming insects is more energy-efficient and consumes less space and water resources. Insects are rich in healthy proteins and essential amino acids, and their saturated fat content is lower than beef. In order to allow the global population to have sufficient food by 2050, we should seriously consider breeding insects, which are a healthier source of protein and more sustainable than ordinary livestock.
  In addition to serving as food, insects also play an important role in the ecosystem. For example, 87% of plants need animals (mainly insects) to pollinate, they have evolved bright petals, fragrant smell and sweet nectar to attract insects. If there is no pollination, wild flowers cannot produce seeds and will eventually become extinct. Cornflowers, poppies, foxglove and forget-me-not will no longer exist. If these plants become extinct, then all places on the earth will lose their vitality, because plants are the foundation of the food chain. The ecological consequences of the sudden decline of insects are far more than the disappearance of wild flowers. Three-quarters of the crops we currently plant also require insect pollination.
  In addition, soil-boring insects can also help aerate the soil. Ants often drop a part of the plant seeds as they drag them back to the cave. These seeds are then sown in various places and take root and germinate. Silkworms spin silk, and bees make honey. In the United States, the ecological role played by insects is worth at least 57 billion U.S. dollars each year, but this valuation is of little significance, because as Edward Wilson once said, if there were no insects, “the environment would be in chaos” and billions of people would suffer from hunger. hunger.
|”Loose Rivets”|

  American biologist Paul Ralph Ehrlich likened the demise of insects to “the constantly loosening rivets on the wings of an airplane.” If one or two rivets are dropped, the airplane may not have a major problem; but if 10, 20, or even 50 are dropped, then a major disaster will occur at a moment that we cannot predict-the airplane will fall from the sky . Insects are the rivets that keep the ecosystem running.

  Although scientists have issued serious warnings, our understanding of insects is far worse than that of vertebrates. We know almost nothing about the biological attributes, distribution areas and numbers of most of the 1 million species of insects currently known. For us, they are often just specimens in the museum indicating the time and place of capture. There are about 4 million species of insects that we have not yet discovered. We are far from aware of the amazing diversity of insects on the earth, but they are rapidly extinct. This is an ironic and cruel fact.
  The speed of insect disappearance is staggering. Since the late 1980s, entomologists from the Kerryfeld Entomological Society in Germany have captured flying insects in nature reserves across Germany. For more than 20 years, they went to 63 locations and caught a total of 53 kilograms of insects. In terms of weight, from 1989 to 2016, the amount of insects they caught decreased by 75%. Midsummer is often the most active period of the year for European insects, and the amount of insects caught during this period has been drastically reduced by 82%. At the beginning, I felt that there must be some kind of error in the data, because the decline was incredible. We do know that the number of wild animals is declining, but three-quarters of the insects have become extinct in such a short period of time. The speed and scale were unimaginable before.

Left: A group of colorful monarch butterflies return to Canada from Mexico. During this year’s migration season, their numbers have decreased by 26%. Right: Stag beetle is protected by law in the UK.

  In October 2019, another group of German scientists published a study on the changes in insect populations in Germany from 2008 to 2017. The results of the study are worrying: the number of arthropods (spiders, psyllids, etc.) in forests and grasslands has been reduced by 2/3 and 2/5, respectively.
  Is it the same in other places? Or is the situation in Germany more special? I think the latter is unlikely. Perhaps the most thoroughly studied insect population in the world is the British butterfly. The volunteers of the “Butterfly Monitoring” program (the largest and longest-running program of this kind in the world) regularly recorded their types and numbers. The results showed a worrying trend: from 1976 to 2017, they were active in farmland, The number of common butterfly species in gardens and other places, such as the meadow brown butterfly and the peacock butterfly, has dropped by 46%. At the same time, even though humans have taken protective measures, the number of rare species such as leopard butterflies and hairline butterflies has dropped by 77%.
  On a global scale, although most insect species-such as flies, beetles, grasshoppers, wasps, mayflies, foam cicadas, etc.-have not been systematically monitored, the number of birds that feed on insects is basically Are decreasing. From 1966 to 2013, the number of birds that prey on flying insects in North America fell by about 40%, higher than that of any other bird. Over the past 20 years, the populations of Cliff Sand Swallows, American Nighthawks, Chimney Thorn-Tailed Swifts, and Barn Swallows have all fallen by more than 70%.
  So far, the earth has calmly responded to a series of changes brought about by mankind, but this may not be the case in the future. In the insect kingdom, the proportion of extinct species is relatively low, but the existing population of almost all wild insects is far less than their former size. They live in a deteriorating and increasingly cramped environment, and they are also facing endless problems created by mankind. Based on existing knowledge, we simply cannot predict how long the dying ecosystem will last, and how far we are from the end of the world. Using Ehrlich’s “rivet on an airplane” as an analogy, the moment when the wing falls may be about to come.