Chapter 16 15 Nature is Rebelling

We have tried, at great risk, to shape nature to our liking, and have failed!It's a harrowing irony indeed.Yet it appears that this is our reality.The truth, though seldom mentioned, can be seen by all, is that nature is not so easily molded, and that insects have found tricks to deftly avoid our chemical attacks on them. Dutch biologist CJ Politier said: "The insect world is the most amazing phenomenon in nature. For the insect world, nothing is impossible; often it seems that the most impossible things will happen in insects." A man who has delved deep into the mysteries of the insect world will be amazed by the wonders that are constantly happening. He knows that here anything can happen, and the utterly impossible will often appear."

This "impossible" is happening now in two broad areas.Insects are being strained to resist chemicals through genetic selection, as discussed in the next chapter.But now we're about to touch on a broader problem that our onslaught of chemicals is weakening the natural defenses built into the environment itself that keep insects from developing.Every time we breached these defenses, a swarm of insects emerged. Reports are coming in from all over the world, and they make it clear that we are in a very serious predicament.After a dozen years of sweeping insect control with chemicals, entomologists are finding that problems they thought were solved years ago are coming back to haunt them.And a new problem arises, as soon as a single insect appears in even inconspicuous numbers, they are bound to multiply rapidly to serious infestation.Because of the ingenuity of insects, chemical control has shot itself in the foot, and chemical control methods have been thrown blindly into battle against biological systems because they were not designed and used with complex biological systems in mind.One can predict the effect of a chemical on a few individual species of insects, but not on an entire biome.

It is fashionable in some places today to disregard the balance of nature; which was the prevailing state in an earlier, simpler world, has now been utterly disturbed. , perhaps we no longer think of the existence of such a state.Some people feel that the problem of natural balance is nothing more than random speculation, but it is very dangerous to use this idea as a guide to action.The natural balance today is different from that of the Ice Age, but it still exists: it is a complex, sophisticated, highly unified system that connects all kinds of life, and it can no longer be ignored. The situation is as dangerous as that of a man who is sitting on the edge of a cliff and blindly defying the laws of gravity.Natural balance is not a static and fixed state; it is an active, ever-changing state of constant adjustment.People are also part of this balance.Sometimes this balance is in man's favor;

In modern times, people have overlooked two important facts when formulating programs to control insects.The first is that the truly effective control of insects is done by nature, not by humans.Insects' limited reproductive numbers are due to what ecologists call environmental defenses, which have been around since the first life appeared.The amount of food available, climate and weather conditions, and the presence of competing or predatory organisms are all extremely important.Entomologist Robert Metcalfe said: "The single most important factor in preventing insects from destroying the peace of our world is the internecine warfare that insects wage within themselves." However, most chemicals are now used to kill All insects, whether our friends or our enemies, are killed.

A second neglected fact is the truly explosive reproductive capacity of some insects that revives once the defenses of the environment have been weakened.The reproductive capacity of many species of organisms is almost beyond our imagination, although we have had moments of enlightenment, now and in the past.From my school days I remember a miracle: To a pot containing a simple mixture of hay and water, just add a few drops of a substance taken from a mature culture containing protozoa, and the miracle is wrought.Within a few days, the jar would contain a swirling, forward-moving swarm of tiny life—billions and millions of tiny, shoe-shaped animals called paramecium.Each as small as a speck of dust, they all multiplied unchecked in this makeshift paradise of temperate temperature, abundance of food, and absence of enemies.The sight reminded me at one moment of the looming barnacles whitening the rocks of the seashore, at another moment the sight of a shoal of jellyfish swimming by, moving mile by mile, their seemingly infinite The trembling ghostly figure is as ethereal as sea water.

As cod migrate across the winter seas to their spawning grounds, we see how nature's control works wonders.On the spawning grounds, each female cod lays millions of eggs.If all the cod eggs had survived to become small fish, the ocean would surely have become a solid mass of cod.Typically, each pair of cod produces millions of juveniles, and only when so many larvae fully survive to develop into adults to replace their parents do they disturb the natural world. Biologists often have a hypothesis: what would happen if an unimaginable catastrophe occurred, the inhibition of nature was lost, and a single species of organisms survived and reproduced.A century ago, Thomas Schuchsler calculated that a single female aphid (which has the uncanny ability to reproduce without a mate) could reproduce in a year's time the equivalent of 100% of the total weight of the U.S. population. a quarter.The dire results of unhinged nature itself have been witnessed by researchers of passive populations.The cattlemen's rush to eradicate the coyotes has resulted in an infestation of voles, formerly the coyotes' controllers.In this respect the oft-repeated story of Kay Baibuck in Arizona is another example.There was a time when the deer was in a state of balance with its environment.A certain number of carnivores -- wolves, jaguars, and coyots -- limit the number of deer to no more than their food supply.Later, in order to "save" the deer, a campaign was launched to kill the deer's enemies - carnivores.As a result, carnivores disappeared, deer multiplied alarmingly, and the area soon ran out of fodder for them.As they feed on the leaves, and the leafless places on the trees grow higher and higher, more deer die of starvation than have previously been killed by predators.Plus, the entire environment has been devastated by the deer's desperate efforts to find food.

Predatory insects in the fields and forests played the same role as the wolves and coyotes of the Kaiberb region.Kill them, and a population of prey insects can flourish. No one knows how many species of insects there are on earth, because there are still many insects that have not been recognized by people.However, more than 700,000 species of insects have been recorded.This means that, depending on the number of species, between 70 and 80 percent of the animals on Earth are insects.The vast majority of these insects are being controlled by natural forces without any interference from man.If this is the case, it is highly doubtful how any enormous amount of chemicals (or any other means) could suppress insect populations.

Unfortunately, little is known about the protection afforded by insects' natural enemies until it is lost.Many of us live in the world, blind to its beauty, its wonders, and the strange and sometimes shocking powers of the creatures that live around us.This is why almost nothing is known about the mobilities of predatory insects and parasites.Perhaps we have seen a strange, menacing-looking insect on a garden shrub, and dimly realized to pray to the praying mantis to exorcise other insects.However, we will understand what we see only when we go for a nighttime walk in the garden and catch a glimpse here and there with a flashlight of a praying mantis slinking towards its prey; and its victims; then we shall begin to feel the meaning of that cruel, oppressive power by which nature controls itself.

Predators—insects that kill and weaken other insects—are diverse.Some of them are agile, as swift as swallows catching their prey in the air.Others scrambled along the branches, picking up and gobbling up immobile insects like aphids.Yellow ants capture the aphid and use its juice to feed their young.The mason wasp builds a columnar mud nest under the eaves and fills the nest with insects that the wasp larvae will feed on in the future.The guardian hornets of these houses fly over the feeding cattle, killing the blood-sucking flies that afflict the cattle.Loudly buzzing hoverflies, often mistaken for bees, lay their eggs on the leaves of aphid-infested plants; the larvae that hatch can then wipe out aphid populations.The ladybug, also known as the "flower lady," is also one of the most effective exterminators of aphids, scale insects, and other plant-eating insects.Literally, a single ladybug can consume hundreds of aphids to fuel its own little fire of energy that the ladybug needs to produce a colony of eggs.

Even more peculiar are the parasitic insects.Parasitic insects do not kill their hosts outright, but use their victims in every appropriate way as nourishment for their own young.They lay their eggs in the larvae or eggs of their captives, so that their own future hatching larvae can obtain food by consuming the host.Some parasitic insects glue their eggs to the caterpillars with mucus; during hatching, the born parasitic larvae burrow into the host's skin.Other parasitic insects rely on an instinct to camouflage by laying their eggs on leaves so that young leaf-eating caterpillars will unfortunately eat them.In the field, in the hedge, in the garden, in the forest, predatory and parasitic insects are at work.Over a pond, dragonflies flitted, their wings blazing with sunlight.Their ancestors once lived in swamps where giant reptiles lived.Today, as in ancient times, they still use their sharp eyes to catch mosquitoes in the air, and use their legs that form a basket to catch mosquitoes.Underwater, the young pupae (also called "ghosts") of dragonflies catch mosquito larvae and other insects in the aquatic stages.There, in front of a leaf, was an imperceptible lacewing, with green gauzy wings and golden eyes, evasively shy.It is descended from an ancient species that lived in the Permian.The adult lacewing mainly feeds on plant nectar and aphid nectar, and always lays its eggs on the stalk of a long stem, attaching the eggs to a leaf.From these eggs emerges its offspring—a strange, upright larva known as the aphid lion, which feeds on preying on aphids, scale insects, or small animals, which it captures and feeds on. Drain their bodily fluids.Each lacewing kills several hundred aphids before its endless cycle of life creates a white silk cocoon to pass its pupal stage.

Many bees and flies have the same ability, and they live entirely by parasitism by destroying the eggs and larvae of other insects.Some of the wasps whose parasitic eggs are extremely small, by virtue of their great numbers and their great mobility, prevent the multiplication of many insects which are harmful to crops. All these little beings are at work--in the sun, in the rain, in the day, in the night, even when the cold of winter has extinguished the fire of life so that only ashes remain. working continuously.But in winter, this vital force is only smoking, waiting for spring to awaken the insect world, and then it will shine again with great vitality.During this time, under the white blankets of snowflakes, under the soil hardened by the severe cold, in the crevices of bark, in hidden burrows, parasitic and predatory insects have found places to hide and escape. Get through this cold season. The eggs of the praying mantis are safely stored in a little box like thin parchment glued to the branch of a bush by its mother, who lived through the dead summer. A female wasp which makes her nest in some forgotten corner of a mansion carries within her body a mass of eggs which will form the whole future colony.The solitary drone sets out in the spring to make a small paper nest, lays eggs in each hole, and carefully raises a small army of workers.With the help of worker bees, she is able to enlarge her nest and develop her colony.During the hot days of summer, the worker bees are constantly looking for food, it is like this, because of the characteristics of insect life and the natural characteristics that we need, all of this has been our way of maintaining the natural balance to make it Confederate forces dumped in the struggle on our side.But now we have turned our guns on our friends.There is a dire danger that we have carelessly underestimated their value in protecting us from dark tides of enemies which, without their help, will flourish and harm us.Insecticides are increasing in number, variety and destructive power every year; consequently, the overall and continuous reduction of environmental defense ability is becoming increasingly obvious and relentless reality.As time goes on, we can expect insect infestation to become progressively more severe, with species spreading disease and destroying crops with more species than we know. "However, is this purely theoretical?" you ask, "Surely this is not going to happen—not in my lifetime, anyway." But it is happening, Right here, right now.Scientific journals have documented about 50 cases of serious disturbances in the balance of nature in 1958.Every year more examples are found.A recent review of this issue referred to 215 reports and discussions of catastrophic upsets in the balance of insect populations caused by pesticides. Sometimes the spraying of chemicals results in a surprising increase in the insects that are supposed to be controlled by the spraying.For example, the number of black flies in Ontario increased by 16 times after spraying compared with before spraying.Also, in England, there was a serious outbreak of cabbage aphids following the spraying of an organophosphorus chemical—an outbreak of the kind not seen before. On other occasions the sprays, while reasonably effective against the very insects they were intended to control, opened up a whole Pandora's box of pests which had never before been abundant. Enough to cause this much trouble.For example, as DDT and other insecticides have killed off the spider mite's enemies, the spider mite has effectively become a worldwide pest.The spider mite is not a species of insect, but a group of barely perceptible eight-legged creatures in the same group as spiders, scorpions and ticks.It has mouthparts adapted for piercing and sucking and an appetite for the chlorophyll that greens the world.It penetrates the outer cells of leaves and evergreen needles with its tiny, sharp mouthparts, and sucks in chlorophyll.The slow spread of the pest leaves trees and shrubs stained with black and white spots like salt and pepper; foliage turns yellow and falls with heavy colonies of spider mites. This happened a few years ago in some national forests in the western United States, when (1956) the U.S. Forest Service sprayed about 885,000 acres of forest land with DDT.The original intention was to exterminate the needle fir bud worm, but that summer it turned out to have created a problem worse than the bud worm.The forest has been observed from the air and great areas of the forest can be seen withered, where the majestic Douglas firs are turning brown and dropping their needles.In the Helena National Forest and on the western slopes of the Great Belt Mountains, as well as in Montana and other areas along Idaho, the forests looked as if they had been scorched.Apparently, this summer of 1957 brought about the worst and most spectacular spider mite infestation in history.Almost all the land that was sprayed was affected by the infestation.Nowhere is the devastation more evident than here.When rangers look back in history, they recall other times when spider mites have wrought natural disasters, but none as impressive as this one. Similar troubles occurred along the Madison River in Yellowstone before 1929, in Florida in 1949, and in New Mexico in 1956.Every pest outbreak follows the spraying of forests with insecticides. (The 1929 spray was before the days of DDT and used lead arsenate.) Why do spider mites thrive more with pesticide use?Apart from the obvious fact that spider mites are relatively insensitive to insecticides, there appear to be two other reasons.In nature, spider mite reproduction is restricted by many species of predatory insects, such as ladybugs, a species of gall wasp, carnivorous mites and some predatory bedbugs, all of which are extremely sensitive to insecticides.The third reason must be found in the population pressure within the spider mite colony.A mite colony that does not constitute a disaster is a dense, settled group that huddles together in a protective belt from enemies.After spraying, the colony disbands, when the mites, though not killed by the chemical, are stinged, and they scatter to find places where they can rest.When this happens, the mite finds much more space and food than was available in the previous colony.With the mite's enemy dead, the mites no longer have to expend their energy maintaining that mysterious protective belt.They concentrate their energy on mass reproduction.It is unusual for them to triple their egg production—all thanks to the effects of insecticides. When DDT began to replace lead arsenate in a valley south of the hills of Victoria, a well-known apple-growing region, a swarm of small insects called red-banded leaf pigeons developed and became a species of growers. disaster.Never before has its harm been so great; the road-money demanded by the petty robber soon increased to demand fifty per cent of the grain; DDT usage increased and it quickly became the most destructive pest of the apple tree. There is irony in this situation.The worst infestation of cod moth (causing "bug apples") occurred in the Nova Scotia apple orchard in the late 1940s in this repeatedly sprayed orchard.In unsprayed orchards, the moths were never abundant enough to cause real trouble. Aggressive spraying has had a similarly unsatisfactory retribution in eastern Sudan, where cotton growers have had a bitter experience with DDT.Some 60,000 acres of cotton in the Gaisce Delta have been irrigated.Spraying was ramped up when early trials of DDT yielded apparently good results.But this is where the troubles begin.Bollworms are one of cotton's most destructive enemies.However, the more sprayed the cotton fields, the more boll worms appeared.Bolls and mature cotton flowers in unsprayed fields suffered less damage than in sprayed fields, and cottonseed yields were significantly reduced in twice-sprayed fields.Although some leaf-eating insects were eliminated, any possible benefit from this was completely outweighed by the boll worm.Finally, it dawned on the cotton growers, unpleasantly, that if they hadn't troubled themselves and spent money on spraying, their cotton fields could have produced higher yields.In the Belgian Congo and Uganda, the consequences of heavy use of DDT against coffee bush pests have been almost a "catastrophe".The pest itself is almost completely unaffected by DDT, while its predators are all exceptionally sensitive to DDT.In the U.S., farmers are increasingly infested with pests in their fields as spraying disrupts the population dynamics of the insect world.Two recent large-scale spraying programs have achieved exactly this effect.One is a program to kill red ants in the southern United States, and the other is to eradicate Japanese beetles in the Midwest. (See Chapters 10 and 7) When heptachlor was used on a large scale in Louisiana farmland in 1957, the result was the liberation of one of sugarcane's worst enemies, the cane borer.Shortly after the heptachlor treatment, the borer damage increased dramatically.Heptachlor, designed to kill red ants, killed the borer's natural enemies.Sugarcane was so badly damaged that farmers were suing the state of Louisiana for failing to warn of the possible consequences. Farmers in Illinois were taught a similarly painful lesson.After a destructive spray of dieldrin had been applied to fields in eastern Illinois for the control of the Japanese beetle, farmers noticed a significant increase in the grain borer in the treated area.In fact, more than twice as many of the insect's destructive larvae were present in the fields where the grain was grown in the treated area as in other areas.Those farmers may not yet know the biology of what's going on, but they don't need a scientist telling them they've bought a premium product.In their attempts to get rid of one insect they have brought upon themselves another, far more destructive pest.According to Department of Agriculture estimates, total damage from Japanese beetles in the United States totals about $10 million per year, while losses from grain borers can reach $85 million. It is worth noting that people have historically relied heavily on natural forces to control grain borers.Within two years of the insect's accidental introduction from Europe in 1917, the U.S. government embarked on a vigorous program to collect and import the pest's parasite.Since then, 24 species of parasites that host grain borers have been introduced to the United States from Europe and the East at considerable cost.Among them, 5 species were considered to be of value for independent control of borers.Needless to say, the gains made by all this work have now been jeopardized because the natural enemies of these imported grain borers have been killed by spraying. If anyone doubts this, consider the case of California's citrus groves.In California, one of the world's most famous and successful examples of biological control arose in the 1880s. In 1872 a scale insect that feeds on orange tree sap appeared in California and within the next fifteen years developed an infestation of such magnitude that many orchards lost their fruit crops.The young citrus industry is threatened by this disaster.At that time many farmers discarded and uprooted their fruit trees.Later, a parasitic insect with a scale insect as a host was imported from Australia, a small ladybug called Vidalia.Only two years after the first ladybug shipments arrived, the scale insects were completely under control in all of California's orange tree regions.Since then, a man has searched for days among the orange groves without finding a single scale insect. By the 1940s, however, these citrus growers were experimenting with new magic chemicals against other insects.Due to the use of DDT and other more toxic chemicals that followed, small ladybug colonies were wiped out in many parts of California, even though the government had spent nearly $5,000 to import them in the past.The activity of these ladybugs saves fruit farmers millions of dollars each year, but one ill-considered action wipes out that benefit.The scale insect infestation is rapidly returning, with more damage than anything seen in fifty years. "This could mark the end of an era," said Dr Paul Diback, who works at the Riverside Citrus Experimental Station. Scale control has now become extremely complicated.Small ladybugs survive only by minimizing their exposure to insecticides through repeated stocking and an extremely careful planning of spraying schedules.And no matter what the citrus growers do, they have to show some mercy to the owners of the nearby land, because the release of insecticide can cause serious damage to the neighbors. All these examples are about insects that attack crops, but what about those that cause disease?There have been many warnings in this regard.One example is Nissan Island in the South Pacific, where spraying had been intensified during World War II, but stopped towards the end of the war.Soon, crowd-infecting malaria mosquitoes re-invaded the island. At that time, all mosquito-eating insects had been killed, and new colonies had not had time to develop, so a large outbreak of mosquitoes was very easy to imagine.Marshall Laird described this scenario when he likened chemical control to a treadmill; once we are on, we cannot stop for fear of the consequences.Part of the world's diseases may be related to spraying in a very unique way.It stands to reason that molluscs such as snails appear to be little affected by pesticides.This phenomenon has been observed many times.Water snails are the only ones that have survived the usual mass mortality caused by the spraying of salt marshes in eastern Florida.The sight was, as it has been described, a horrific picture--it resembled something created with the brush of a surrealist painter.Among the dead fish and the dying bodies of crabs, water snails crawled and devoured the victims of the deadly poisonous rain. But what's the point of all this?This phenomenon is important because many snails can host many parasitic worms that spend part of their life cycle in molluscs and part in humans.An example is schistosomiasis, which can enter the body through the skin and cause serious illness in people when they drink or bathe in infected water.Schistosoma enters water bodies by means of snail hosts.The disease is especially widespread in Asia and Africa.Where schistosomes are present, insect control methods that promote snail blooms always seem to have serious consequences. Of course, humans are not the only victims of diseases caused by snails.Liver disease in cattle, sheep, goats, deer, elk, rabbits, and various other warm-blooded animals can be caused by liver flukes that spend part of their life cycle in freshwater snails.The livers of animals infested with these worms are unfit for human food and are routinely confiscated.This loss costs American cattle ranchers approximately $3.5 million annually.Any activity that causes an increase in snail populations will significantly exacerbate the problem. These questions have cast a long shadow over the past decade, yet our understanding of them has been slow.Most of those who can afford to delve into methods of biological control and help put them into practice have been too busy toiling in the more exciting little world of chemical control. It was reported in 1960 that only 2% of economic entomologists in the United States worked on the field of biological control, and the remaining 98% of the key personnel were employed to study chemical insecticides. Why is this the case?Some major chemical companies are pouring money into universities to support research efforts in pesticides.This situation produces scholarships and attractive positions that attract graduate students.On the other hand, biocontrol research has never been donated to—for the simple reason that biocontrol cannot promise anyone the kind of luck that occurs in the chemical industry.Biocontrol research is reserved for state and federal clerks, where wages are much lower. This state of affairs also explains the not-so-mysterious fact that some eminent entomologists are leading the defense of chemical control.Background checks on some of these individuals revealed that their entire research programs were funded by the chemical industry.Their professional prestige, and sometimes even their work itself, rests on the perpetuation of chemical control methods.Literally, can we expect them to bite the hand that feeds them? Amid the general cheer for chemicals as a fundamental method of controlling insects, occasional reports of a handful of studies were made by a handful of entomologists who did not lose sight of the fact that they were neither chemists nor engineers, they is a biologist. Britain's F. H. Jikber stated: "The activities of many who you call economic entomologists may lead people to think that they are doing it because they believe that saving the world depends on sprayer nozzles... They believe that when After they create a problem of pest resurgence, insect resistance, or mammal poisoning, chemists will invent another drug to treat it. It is not recognized that ultimately only biologists can provide the answer to the problem of eradicating pests ".Nova Scotia's AD Pikett writes: "Economic entomologists must realize that they are dealing with living things... and their work must be more than simple experiments on insecticides or on stronger insecticides. Measuring destructive chemicals is more complicated." Dr Pickett himself was a pioneer in the field of research to develop rational methods of insect control that take advantage of a variety of predatory and parasitic insects. Dr. Pickett began his research some 35 years ago in the apple orchards of Nova Scotia's Annapolis Valley, which at one time had the highest concentration of fruit trees in Canada.At that time, it was believed that insecticides (then only inorganic chemicals) could solve the problem of insect control, and it was believed that the only thing to do was to teach fruit growers how to use them according to the recommended methods.However, this beautiful vision has not been realized.For some reason, the insects are still active.So new chemicals were thrown in, better spraying equipment was invented, and enthusiasm for spraying grew, but the insect problem didn't get any better.Later, it was said that DDT could "dispel" the "nightmare" of cod moth outbreaks; in fact, the use of DDT caused an unprecedented infestation of mites."We've just gone from one crisis to another, trading one problem for another," Dr Pickett said. In this respect, however, Dr. Pickett and his colleagues forged a new path, abandoning the old path followed by other entomologists; Keep running at the heels of the will-o'-the-wisps of increasingly toxic chemicals.Recognizing that they had a powerful ally in nature, Dr Pickett and colleagues devised a program that maximized natural control and minimized pesticide use.When it is necessary to use insecticides, the dosage is reduced to the minimum amount, so that it is sufficient to control pests without causing inevitable damage to beneficial species.Planning also includes choosing the right timing for spraying.For example, if nicotine sulphate was sprayed just before the flowers of an apple tree turned pink, rather than after, an important predatory insect would be preserved, possibly because of the It is still unhatched in the egg before turning pink. Dr. Pickett deliberately selects chemicals that are least harmful to parasitic and predatory insects.他说：“如果我们在把DDT、对硫磷、氯丹和其他新杀虫剂作为日常控制措施使用时，能够按照我们过去使用无机化学药物时所采用的方式去干，那么对生物控制感兴趣的昆虫学家们也就不会有那么大意见了。”他主要依靠“尔叶尼亚”(由一种热带植物的地下茎演化而来的一个名字)、尼古丁硫酸盐和砷酸铅，而不用那些强毒性的广谱杀虫剂，在某些情况下使用非常低浓度的DDT和马拉硫磷(每100加仑中1或2盎斯——而过去常用100加仑中1或2磅的浓度)。虽然这两种杀虫剂是当代杀虫剂中毒性最低的，但毕凯特博士仍希望进一步的研究能用更安全、选择性更好的物质来取代它们。 他们的那个规划进行得怎么样呢？在诺瓦·斯克梯雅，遵照毕凯特博士修订的喷药计划的果园种植者们和使用强毒性化学药物的种植者一样，正在生产出大量的头等水果，另外，他们获得上述成绩其实际花费却是较少的。在诺瓦·斯克梯雅苹果园中，用于杀虫剂的经费只相当于其他大多数苹果冲植区经费总数的10一20%。 比得到这些辉煌成果更为重要的一个事实是，即由诺瓦·斯克梯雅昆虫学家们所执行的这个修改过的喷药计划是不会破坏大自然的平衡的。整个情况正在向着由加拿大昆虫学家G·C·尤里特十年前所提出的那个哲学观点的方向顺利前进，他曾说：“我们必须改变我们的哲学观点，放弃我们认为人类优越的态度，我们应当承认我们能够在大自然实际情况的启发下发现一些限制生物种群的设想和方法，这些设想和方法要比我们自己搞出来的更为经济合理”。