Expert of this article: Zhang Qikai, Chinese Academy of Agricultural Sciences, Ph.D. in insect ecology
Reviewer of this paper: Wu Shengyong, associate researcher of Chinese Academy of Agricultural Sciences
"Buzzing ~ buzzing", is it a long time without night Hear the annoying noise of mosquitoes? Mosquito populations dwindle in the cold autumn and winter months, and when the weather warms the following year, they make a comeback.
There is a saying that "killing one overwintering mosquito is equivalent to eliminating the second generation of thousands of mosquitoes". Is it true?
Where do these mosquitoes go in winter? Did you freeze to death or find a place to hide? Let's talk about it today.
How productive are mosquitoes?
mosquitoes belong to insect class Diptera mosquito family, about 3000 species, widely distributed all over the world.
Usually, only female mosquitoes are blood-sucking, and they use the body's heat, sweat and exhaled carbon dioxide as cues to locate, and use their piercing mouthparts to suck blood. The mouthparts of mosquitoes are composed of two serrated needles, two lancets, a salivary tube and an esophageal tube. When they are sucking blood, they will first cut the skin with the serrated needles and secrete anesthetic substances to relax the muscles. Next, a lancet is inserted into the skin to look for blood vessels to draw blood.
The mating time of mosquitoes is very short, usually within 15s, and the mating site is usually in the air. Some male mosquitoes will stay by the side of the female mosquitoes before they emerge, and once the female mosquitoes break out of their shells, the male mosquitoes will grab them and mate with them. There are also male mosquitoes that search for females next to humans, using carbon dioxide as a clue.
There are also some male mosquitoes that will gather together to attract females to join them, and when the females fly into the group of males, the males will find the females to mate with based on the frequency of their wing vibrations.
female mosquitoes must suck blood after mating to obtain proteins in the blood to promote ovarian maturation. After sucking blood, it will lay eggs in water, and it can lay eggs 6-8 times in its lifetime, 200-300 eggs each time.After two days, they will hatch into mosquito larvae - larvae (jié jué), the larvae feed on microorganisms in the water and algae, after 4 times of molting, will pupate, 2-4 days later The pupa shell bursts, and the buzzing mosquito we usually see is born, and it only takes 10-12 days to complete a generation.
Where do the mosquitoes go in winter?
The living conditions of mosquitoes have a lot to do with temperature. The most active temperature of mosquitoes is 28 degrees to 30 degrees. At about 16 degrees, they start to react slowly, and they freeze to death in a few days below zero. Of course, some mosquitoes with strong anti-adversity ability will not freeze to death, and they will choose to hibernate to preserve their strength. So, every autumn, mosquitoes eat frantically, how can they hibernate without having enough food?
So in winter, mosquitoes hide around us, such as basements, bomb shelters, warehouses, flower houses, pipes, wall cracks, wardrobes, corridors, gutters, under beds, sewers, etc. They are in diapause in these places. Generally speaking, it is because the outside world is too cold to slow down the metabolism, and secrete a substance that produces a large amount of glycerol , so that the water in the body will not destroy the cells due to low temperature freezing. It will reappear with us in the spring of next year.
In addition to overwintering as adults, mosquitoes can also overwinter as eggs. They lay their eggs in water when winter comes, and these eggs are also diapause.
Eliminating one overwintering mosquito is equivalent to eradicating thousands of mosquitoes for the second generation?
Overwintering mosquitoes will lay thousands of eggs in the spring of the following year. Studies have shown that the number of overwintering mosquitoes will directly affect the number of mosquitoes in the coming summer. In addition, the activity of overwintering mosquitoes is weak and the distribution is concentrated, which is a period that is easy to eliminate. Therefore, eliminating overwintering mosquitoes is the key to mosquito control.
What is the difference between male and female mosquitoes?
antennae are different: the antennae of female mosquitoes are similar to hornwort , and are sparser. The antennae of male mosquitoes resemble feathers,There is a lot of dense fluff on it.
Mouthparts are different: The mouthparts of the female mosquito consist of six needles, two of which are on the upper jaw, two on the lower jaw, and one on each of the tongue and lips, and the mouthparts are longer. The mouthparts of male mosquitoes are thin and short, making it difficult to pierce human skin
Abdomen is different: the abdomen of female mosquitoes is rounder, flesh-colored, and has obvious patterns. Male mosquitoes have green abdomens without patterns.
Different feeding habits: The main food source of female mosquitoes is blood. Male mosquitoes feed mainly on plant nectar and sap.
However, some self-respecting male mosquitoes will also go to suck blood, after all, do not want to lose the mosquito's face. , a entomologist at UC Davis , found that male mosquitoes also feed on blood, but at a terrible cost. The researchers did an experiment for this, feeding water, sucrose solution, and pure blood to male mosquitoes. The results showed that the male mosquitoes that drank sucrose survived for a month, while the pure-blooded male mosquitoes survived for up to 5 days, as long as drinking water.
Why do male mosquitoes die easily when they suck blood? In fact, the blood of vertebrates is poison to insects, and there are very few insects that can suck blood. When insects digest hemoglobin after sucking blood, they produce a toxin called heme. However, only insects with blood-sucking ability will produce a layer of peritrophic membrane on the inner wall of their field after blood-sucking. It has the functions of preventing tissue damage, controlling the secretion of digestive enzyme, preventing pathogen interference, etc. At the same time, it can block and degrade heme. . The male mosquito does not have this protective film, so the male mosquito will die suddenly after sucking blood, which may be poisoned by heme.
How to repel mosquitoes?
- Mosquito coils
Mosquito coils are the most effective compared to other less common methods of repelling mosquitoes. The active ingredient in mosquito coils is pyrethroid , which is a highly effective nerve agent. When mosquitoes are exposed to this drug, it will change the ion channels of their nervous system,Let him be excited first, then gradually paralyzed, and finally die. It is worth mentioning that the toxicity of mosquito coils to the human body is very low, but also pay attention to ventilation.
There are also many kinds of pyrethroids. The active ingredients of mosquito coils currently on the market are generally perfluthrin, perfluthrin, and some are also useful propargyl , trimethrin. The difference between them lies in the level of toxicity and efficiency. It is recommended that pregnant women or children use less toxic tetraflumethrin.
- mosquito repellent liquid
mosquito repellent liquid's active ingredients are DEET , icaridin, DEET and so on. They play a role in preventing mosquitoes by interfering with the olfactory system of mosquitoes and blocking proteins that affect the sense of smell. To put it bluntly, when you spray mosquito repellent, mosquitoes can't find you. So spray on yourself or mosquitoes, not your clothes.
Safety ranking: DEET>Icaridin>DEET
Effect ranking: DEET>Icaridin>DEET
How to kill in winter mosquito?
In winter, you can clean up the excess bottles and cans at home, and change the water frequently for aquatic plants and bonsai at home, which can greatly reduce the hiding places of overwintering mosquitoes.
Source: Popular Science China
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