Locust is a common insect. In the past, in autumn, it was almost everywhere. When I was a child, I went to shoot hundreds of locusts in the field one afternoon and then took them home for frying, which would become a snack for my father and grandfather.

But in general, locusts live alone and only appear in pairs during the breeding season. However, once a large number of locusts are found to gather, it means that the locust plague is about to begin. At that time, millions, tens or even hundreds of millions of locusts would cover the sun and nothing would grow in their place.

Formation of locust plague

Locust is the general name of all insects in ORTHOPTERA Acridoidea. Together with Tetrigoidea and Acridoidea, they form Acridoidea. The biggest difference from the other two subfamilies is that locusts have strong hind legs, strong jumping ability, long tentacles and very developed wings. (The picture below shows the most common member of Acridoidea-Locusta migratoria manilensis)

Locust is not a natural "devil", because it is not an easy thing to form a locust plague, it needs "the right time, the right place and the right people" (a derogatory term). We ancients often said that "the right time, the right place and the right people are harmonious." Drought will expose a large number of riverbeds. Although the river bed is dry, it has high water content and is suitable for locust hatching. In this way, a large number of locusts gather on the riverbed to lay eggs, and the hatching rate will be greatly improved under the protection of water.

In addition to drought, waterlogging will also form locust plague. For example, the protagonist of the locust plague in East Africa is a desert locust, which originally lived in the desert area of East Africa. Due to excessive drought, the survival rate and hatching rate are very low, but the continuous rainfall in East Africa broke the desert environment with little rain, greatly increased the hatching rate of desert locusts, and finally formed a locust plague.

Poisonous locusts?

In fact, there is an essential step for locusts to form a locust plague, that is, gene mutation. By studying the genes of common locusts and locust-infested locusts, scientists found that the locust-infested locusts had gene mutation, which led to the accumulation of a large amount of phenylacetonitrile (PAN) in their bodies. Phenylacetonitrile itself is a toxic substance with certain irritation. Inhalation can cause dizziness, headache, nausea, vomiting and other symptoms.

This is undetectable in common locusts. Through further research, scientists found that it was phenylacetonitrile catalyzed by CYP305M2, a gene encoding CytP450 oxidase in locusts, which may also be an important reason why locusts changed from living alone to living in groups.

However, only the existence of phenylacetonitrile in the body is far from over. Through further research, scientists found that birds that like to eat locusts have moved away. Obviously, this is not scared by a group of locusts. After all, if it is normal, this is a lump of protein delivered to the door.

So, what makes birds avoid locusts? Is it phenylacetonitrile? The answer is half right, because swarms of locusts release a large amount of phenylacetonitrile, which really makes some birds avoid it. For example, scientists once smeared phenylacetonitrile on the favorite prey of great tits, and as a result, more than 90% of great tits refused to prey on this whitefly.

But there will still be birds rushing into the locust swarm to eat in chunks, and the locusts did not give in easily at this time.

Studies have shown that when locusts are attacked by birds, they will convert phenylacetonitrile into more deadly hydrogen cyanide (HCN) through a series of reactions. Compared with phenylacetonitrile, HCN is more volatile and easier to be captured by birds' sense of smell, which is a very dangerous signal for birds.

Therefore, even if some birds are not discouraged by phenylacetonitrile, they will be discouraged by hydrogen cyanide before preying, which means it is almost impossible to solve the locust plague by birds.

Since birds are afraid of locusts, why can ducks be used to control locusts?

In ancient times, industrious people were never passively beaten in the face of locust plague, but actively sought solutions. Finally, people found a good way-grazing ducks to control locusts.

Even in modern times, raising ducks is still used to control locusts. For example, in 2005, 30,000 ducks were transported from Zhejiang to control the locust plague. As a result, the plague of locusts on 6.5438+0 million mu of land was solved in three months. From this point of view, ducks really seem to be able to resist the toxicity caused by locusts. Is that really the case? Actually, it is not.

As we all know, ducks are domesticated by crossing wild ducks and spotted ducks. In fact, these two kinds of ducks contain locusts in their recipes, which means that ducks themselves are one of the natural enemies of locusts.

Secondly, phenylacetonitrile and hydrogen cyanide are highly toxic to most vertebrates. It's okay for ducks to eat a few locusts, but they still burp when they eat too much. After all, it is hooliganism to talk about toxicity without dose.

The real function of ducks is actually to drive away locusts. Because locusts are very destructive, they can finish eating a crop in a short time without leaving an inch of grass. If ducks are in this crop field, they will have a good deterrent effect on locusts, so that they dare not stay too long. After all, toxicity can prevent them from being eaten as much as possible, but it is instinct to actively avoid natural enemies.

Because of this, 30,000 ducks wiped out the locust plague in Xinjiang in only three months, and their strategy was to keep driving and transferring. Of course, there is some truth in herding ducks to control locusts, but only before locusts form. Before the formation of locusts, there will be a large number of locusts in this area, and at this time these locusts have not produced genetic mutations. At this time, if you drive the ducks over, you can really have a full meal, and by the way, kill the locusts in the cradle.

finally

If a plague of locusts has occurred, a flock of ducks are obviously looking for death when they rush into the locust swarm, because once they eat too many locusts, animals of this size, even people, have to be knocked down. Moreover, ducks also have a sense of smell, and they can feel the malice released by locusts, so it is obviously unrealistic to let them drive away or kill locusts and let them eat them before the locust plague forms.