Can foodies eat up all the invasive species? Don't overestimate the ability of foodies

Recently, the topic of invasive species has frequently been on the hot search, from the alligator gar that is caught even if the entire lake is drained, to the Canada goldenrod that the government once encouraged citizens to report if they see it. Going back further, other invasive species that have attracted widespread attention include bullfrogs, tilapia, crayfish, and golden apple snails. Every time the topic of invasive species comes up, there will always be a voice like this: our foodies will eat them to extinction in a matter of minutes. Even when talking about invasive species from foreign countries, some netizens said: just send Chinese foodies over there.

But can foodies really send invasive creatures to their graves and save the world?

The answer is: No.

In the early years, there were rumors such as "818 alien species invaded the Great Eating Empire". The rumors were very beautiful, but unfortunately they were not scientific.

Putting aside whether Chinese foodies can eliminate invasive species from other countries, just looking at China's invasive species alone, according to data from the China Alien Invasive Species Database and the Alien Invasive Species Prevention and Control Research Center of the Ministry of Agriculture, as of November 2020, there were 754 recorded invasive species in China , with estimated economic losses exceeding 120 billion yuan each year.

Foodies, you think you can solve the problem of invasive species?

What are invasive species?

Invasive species are a subset of introduced species. If a species is artificially introduced into an area where it did not exist naturally before, and if there is no further human intervention, this species may develop to a certain number in the local area, threatening the local biological diversity and becoming a local nuisance, this species can be called an "invasive species".

A species is not always an invasive species. For tens of millions of years, the tragedy and comedy of species replacement has been played out in the global ecosystem, but this process is slow and can only occur under natural conditions - however, humans have changed all of this.

The crayfish (official Chinese name: Procambarus clarkii), which everyone loves to eat, is also an invasive species. They harm native species by preying on local animals and plants, carrying and spreading pathogens, etc.｜Ansheng

Humans have an unprecedented advantage in species mobility: transportation . This allows some species to hitch a ride with humans and easily reach unfamiliar corners they have never been to. In fact, not all species that arrive in foreign places will become invasive species. A large number of introduced species face an environment that they cannot adapt to in the short term; for those species that humans actively introduce into foreign lands for some economic purpose, people often have to actively create suitable habitats for them to survive.

However, a small number of species have come to their new continent with the help of humans, and the new environment is unexpectedly suitable for their survival . In this case, they can live well without the help of humans. Once they escape human control, the factors that curb their population growth in their native habitats will completely disappear, and these species will become wild horses and form wild populations. There are many ways for these species to dominate in foreign lands - some use their potential survival advantages to invade the living space and resources of native species; some have a wide range of food habits and accept all kinds of food, and directly feed on native species; others can secrete toxins or have other means to suppress the survival of native species.

"Asian Carp" in Australia's Maribyrnong River｜Vaderluck / wiki commons

In addition, invasive species are not necessarily born with sharp teeth and fully armed to destroy all other organisms. A species whose population is effectively suppressed in one place may become an invasive species in a place with different environmental factors.

After getting familiar with these basic concepts, let's analyze a few cases.

The invasion started because of foodies

Let’s first look at the American bullfrog, golden apple snail and tilapia. The invasion of these species was caused by blindly introducing foreign species as food without considering the market capacity. Simply put, the reason why these species became invasive foreign species in China is precisely because the original introducers overestimated the fighting power of Chinese foodies, coupled with the lack of effective breeding control and environmental isolation .

The American bullfrog (Rana catesbeiana) is native to North America. In the United States, it is called bullfrog, named after the rough and low sound it makes during mating, which is like the mooing of a bull. The bullfrog is not only the largest frog in North America, but also has a tough personality and a good appetite . Its diet far exceeds the insects, snakes, mice, fish, turtles, and crayfish that ordinary frogs eat. Any living creature it can catch, including many birds, is its food. Even its tadpoles pose a threat to small fish in the water where they are located.

Bullfrog tadpoles | Gary Nafis / californiaherps.com

Due to the extensive breeding conditions and the fact that early people had no awareness of controlling the introduction of animals, bullfrogs escaped into the wild in Asia very early, becoming wild species and then invasive species .

The first recorded invasion of bullfrogs into China was in 1959, when they entered China from Hong Kong. However, the invasion on a larger scale occurred after the economic opening up in the 1980s and 1990s. With the "special breeding" in various parts of southern China, a large number of unfamiliar animals and plants were seen as the golden key to wealth and were introduced into China. Bullfrogs were one of them. However, compared with native wild frogs in China, such as spiny-chested frogs, tiger-striped frogs, and black-spotted frogs, bullfrogs have a rough texture and are not favored by gluttons, which led to poor sales. As a result, a large number of breeding sites were abandoned, and the escaped American bullfrogs replaced many native frogs .

Similar to this is the golden apple snail (Pomacea canaliculata) . The golden apple snail is native to the Amazon River Basin in South America. It was introduced to Taiwan for breeding in the 1970s as food. Later, due to the poor quality of the meat, a large number of them were discarded, and they became rampant. After the 1980s, the mainland did not learn from the lesson, and the consequence of the introduction was to repeat the same mistakes. Because of its strong reproductive ability, the golden apple snail is now found in almost all water bodies in southern China.

Pomacea apple snail egg mass｜floridatimeforgot.com

If the bad taste can be considered an excuse that can barely forgive foodies, then the fact that tilapia has become an invasive species is more a result of cultural traditions and low acceptance.

Tilapia is not just one kind of fish, but a general term for a variety of fish species from the genus Oreochromis and the genus Tilapia of the family Cichlidae that have been introduced into China for aquaculture. They have tender meat and a wide range of diets. They are a protein source recommended by the United Nations World Food Program and are farmed and bred by institutions in the United States, Israel, and India.

Tilapia｜fishbase.se

But in China, the problem lies in its acceptance. Because its appearance is completely different from the four major fish species that are traditionally farmed for consumption, and because tilapia grows quickly, some people who do not accept it regard it as "raised in manure water." This view (or perhaps prejudice) not only causes the failure of farming and species escape in some places, but also makes it impossible for people to catch tilapia that flow into the wild environment, causing a wider invasion.

Some rumored cases of intrusion

The invasion of nutria (Myocastor coypus) has little to do with foodies. They were first introduced to China from the Soviet Union as fur animals. After the 1980s, they also formed a special breeding boom, and then escaped into the wild and became an invasive species. Currently, the nutria meat and processed products we can see in the market or restaurants are all from breeding, because the cost of breeding nutria is lower than the cost of catching them in the wild. The wild population of nutria in China is not large enough to be easily captured by humans. Their invasion mainly damages dams and crops .

Nutria｜Alpsdake / wiki commons

Anthemis tinctoria, Chrysanthemum coronarium, and Gynura crepidioides also appear on the list of invasive alien species, but none of them are on the list of serious threats. In fact, some flowers that we are familiar with, such as marigold, autumn lily, and cornflower, are on this list, which means that there is evidence that they have established populations in the wild, but have not yet caused serious economic and ecological damage .

A few years ago, there was the "piranha incident" that caused panic . This incident also made some friends realize the power of invasive species at the time - however, this incident was later proved to be a farce. "Piranha" generally refers to a variety of fish under the subfamily of the serraticidae of the family Characidae of the order Characidae. They have sharp teeth and live in groups and have carnivorous habits. There is no definite information indicating that any kind of "piranha" has established a population in the wild in China, and no kind of "piranha" has been included in the list of invasive alien species in China. "Piranha" is very sensitive to temperature. Even if some "piranhas" escape into China's freshwater bodies, they cannot establish a population and cannot survive the winter.

For example, this Weibo post.

Some fish species of characins have been introduced for breeding. They are all members of the genus Piractus, and are generally called freshwater white pomfret in the market. One of them, Piractus mesopotamicus, has been included in the Chinese invasive species database and is often the target of false reports of "piranha" in various places. In any case, they are omnivorous fish, delicious and non-aggressive. The impact on the environment is another matter, but foodies really can give it a try.

Rumors are not limited to the country

There are also some rumors about invasive species in foreign countries, such as "Mussels invaded Western Europe and North America". The invasion described is roughly accurate, but the invasive species is not mussels, but zebra mussels (Dreissena polymorpha).

Zebra mussels are native to the Caspian Sea and the Black Sea. In the first half of the 19th century, they were brought to ports in Western Europe such as the United Kingdom, Ireland, and Spain along with human ships. Because of their strong adhesion and reproduction ability, they caused damage to local port facilities and have been invading the Netherlands, the Czech Republic, and Sweden. In 1973, they arrived in Italy. In 1988, they were first discovered in Windsor, Canada and Detroit, USA. In the past few decades, zebra mussels have spread wildly throughout the Great Lakes region. Their main harm to the ecology is that they reproduce rapidly and uncontrollably, which is enough to change the energy flow of the ecosystem. And because of their potential to accumulate toxins and pollutants, experts do not recommend eating zebra mussels (although they can be eaten). The United States spends $500 million a year to control the spread of zebra mussels.

Zebra mussels in the Netherlands | Bj.schoenmakers / Wikimedia Commons

The shellfish we call mussels are several species of the family Mytilidae that live on the coast of East Asia. Although they can sometimes cause damage to port facilities, they are native species and their numbers are effectively controlled by other organisms, so they do not cause serious problems.

Unfortunately, foodies can't save the world

So far, the analysis of the errors in the classic case of "foodies saving invasive species" has ended. However, in a broader sense, invasive species are far from being a problem that can be solved by humans "eating" them .

Take China as an example. Among the 754 recorded invasive species, 134 are various microorganisms and plant diseases. The vast majority of animals are insects, and most of the plants are inedible. As human "foodies", we are so useless. We can use this to expand our thinking and use the "foodies" of other species to help us solve problems, which is the so-called "biological control".

Striving to maintain the status quo of the environment while developing the economy is currently the best strategy for mankind to continue civilization. Therefore, doing our best to control the number and types of invasive species , together with environmental protection, should be a means of continuing civilization.

Author: Uncle Zhong

This article comes from the Species Calendar, welcome to forward

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