On May 23, Ditan Park, the disease control staff was checking the mosquito trapping equipment. The device traps mosquitoes by releasing carbon dioxide. Beijing News reporter Wang Jianing photo
As the temperature climbed and mosquitoes awakened, the monitoring of mosquito density in Beijing also kicked off. This week, more than 400 “small lights†were trapped in various public places in Beijing to trap mosquitoes. It is estimated that the current mosquito density in Beijing is 0.26/light·hour, which has not yet reached the peak of mosquito density. Among them, the mosquito density in hospitals and scenic spots is low, and the mosquito density in residential areas is the highest, reaching 0.34.
Test tool: carbon dioxide mosquito lamp
Test procedure: Hanging lights in parks, residential areas, private houses, hospitals, scenic spots and farms, hanging for 2 hours to attract mosquitoes, and counting the number of females to calculate the mosquito density.
Testing process
Point "carbon dioxide mosquito lamp" to catch mosquitoes
In mid-May, the reporter followed the staff of the Dongcheng District CDC to go to one of the mosquito density monitoring sites, Ditan Park.
Mosquito density monitoring began around 6 pm. Just after a light rain, the air was so cold, the staff used a small car to hold four groups of mosquito traps and stopped by a green area near the south gate of Ditan Park. The monitoring method used that night was a common "light trap" and the tool was a "carbon dioxide trap".
The "head" of the mosquito lamp is a small metal plate with a reverse buckle for hanging at night; the abdomen is a small iron ring. After the power is applied, the middle blade rotates to form an air flow, which can suck the mosquito into the net pocket below it. And fall into the tail storage box.
Attracting mosquitoes is a carbon dioxide tank placed on the ground. After the switch is turned on, carbon dioxide is released through the duct. The outlet of the duct is fixed near the small lamp. The mosquito likes to be close to the place where the carbon dioxide concentration is high. Once the duct is approached, the airflow will be Inhaled into the storage box.
After the mosquito lamp was assembled, it was hung on four large tree branches. At the scene, many people who were bent at night stopped curiously and asked about the usefulness of these small lamps.
When to measure mosquitoes, there are also some considerations. According to the uniform requirements, the staff will hang lights one hour before sunset and one hour after sunset. “We will check the flag-raising time of Tiananmen before the test. It is consistent with the sunset time.†Wei Xuqiang, a staff member of the Dongcheng District CDC, is an expert in the study of mosquitoes. He introduced that after the lights are turned off, they will sort out the female mosquitoes and sort them out. Sometimes, certain types of mosquitoes are handed over to the higher-level CDC for testing.
Wei Xuqiang told reporters that residential areas, medical institutions, tourist attractions and other places will also carry out mosquito density measurement. Due to the better environment in the urban park, there are regular personnel to deworm, and the number of mosquitoes will not be much, plus just after the rain Many mosquitoes will hide under the eaves and leaves, and the activities are not active.
After more than an hour of hanging lights at night, the reporter found that three mosquitoes were “dropped†in the storage box. Finally, a total of 4 mosquitoes were captured at the point.
Test Results
The lowest mosquito density in hospitals and tourist attractions
In order to grasp the distribution of mosquitoes in Beijing, every 10 days, the CDCs in each district will choose different environments in the area to carry out “distribution†and monitor the number and density of mosquitoes through various methods. This week, Beijing completed the mosquito density measurement by light trapping method in mid-May. This time, the measurement was 428 共, which attracted 222 mosquitoes and the mosquito density was 0.26/light·hour.
The monitoring environment is divided into six categories, including residential areas, park green spaces, hospitals, houses, farms and tourist attractions. From the data point of view, the mosquito density in the residential area is the highest, 0.34, followed by the farm, 0.31 . Hospitals and tourist attractions performed best, with mosquito densities of 0.1 and 0.13, respectively.
Of the mosquitoes detected, 214 were Culex pipiens pallens, and the Aedes albopictus (commonly known as "flower mosquito"), which has received much attention, has fewer, only seven.
Wei Xuqiang said that Beijing has not yet entered the heat, and now the wintering mosquitoes have just begun to wake up, so the number is not much. Mosquito density monitoring will continue into the summer, and in July and August, the density of mosquitoes in Beijing will reach a peak.
Popular science
What are the measures to attract mosquitoes?
Measuring mosquito density, carbon dioxide mosquito lamp is not the only way.
Wei Xuqiang introduced that in addition to the carbon dioxide trapping lamp method, the method of human seduction, larval spoon, and oductor is also a more common method in Beijing. Each of these methods has advantages and pertinence.
The method of seducing people to stop: the carbon dioxide mosquito lamp method is sometimes carried out together with the human inducement method. The human trapping method is suitable for the monitoring of human-adult-resistant mosquitoes, and the required device has a counter, a flashlight, an electric mosquito trap, and the like.
During the monitoring, the shade is selected as the monitoring point. At the peak of the local mosquito hedgehog, the monitor exposes one side of the calf to be stationary. In half an hour, once the mosquito stops on the calf, it is photographed dead or electrically sucked. The capture is recorded in the statistics. Once there is a major mosquito-borne disease in the area, the law is discontinued to ensure safety.
Larvae scoop method: Suitable for mosquito larvae (sputum) in large and medium-sized water bodies. The monitor follows a large and medium-sized water body, selects a sampling point every ten meters, quickly picks up a spoonful of water from the water with a water scoop, sucks out the larvae and puts them into the numbered sampling tubes for sorting. In residential areas, the straw method is chosen for measurement.
Zeng Xiaotong, deputy director of the Municipal Center for Disease Control and Prevention, said that mosquitoes breed in the water, but many citizens lack the knowledge to identify mosquitoes, but they cannot distinguish them. During his visit, he found that in the pots and pots filled with water in many people's homes, a spoonful of young mosquitoes can be found. Compared with the elimination of adult mosquitoes, cleaning water bodies and eliminating young mosquitoes is a more effective way to control mosquitoes.
Ovum method: mainly for Aedes albopictus and Aedes aegypti mosquito eggs. The utensils used included an ovipositor, white filter paper and ice packs. At the monitoring site, the ovipositor was placed continuously for 4 days, and the adult and mosquito eggs were inspected and collected on the last day, and the number of positive bottles and the number of adult mosquitoes were recorded.
The shape of the oductor is specially designed for the breeding of Aedes mosquitoes. The cap is round black plastic, the bottle is a cylindrical transparent plastic bottle, and there are three inverted conical tubes protruding inward on the cap. The mouth is small, and once the female mosquitoes fly in, it is difficult to fly out again.
Tips
High respiratory rate
According to the Municipal Center for Disease Control and Prevention, it has been confirmed that people with developed sweat glands, high body temperature, and high respiratory rate (ie, high carbon dioxide) are more likely to be attracted by mosquitoes than dark clothes.
To reduce mosquito bites, you should always take a bath to keep your skin fresh and wipe off sweat when you sweat. Also use less soap and perfume, and mosquitoes like nectar.
Some natural plants have a repellent effect on mosquitoes. For example, night scent, sage, the most obvious of which is pyrethrum, which has a strong repellent or even killing effect on mosquitoes. Mosquitoes such as lemongrass oil, lemongrass and geraniol do not like it.
When working in places with more mosquitoes, try to wear light-colored long-sleeved clothes and wear socks at the same time. This can reduce mosquito contact. Mosquitoes can reduce the humidity of human skin, reduce the volatiles on the skin, and reduce bites.
In addition, mosquitoes are not all night-time animals. For example, Aedes albopictus, which spreads dengue fever, generally likes to be active during the day, so it is also necessary to prevent mosquitoes during daytime activities. It is best to use a mosquito repellent (repellent) when performing outdoor activities in green belts, forest belts, etc. during the day. The mosquito repellent is usually effective for 4 hours.
Beijing News reporter Dai Xuan
(Editor: Qiu Guanglong HF056)
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