In June, Shanghai officially entered the flood season, according to the forecast, this year's Shanghai flood season total precipitation is more, is conducive to the growth and reproduction of mosquitoes, it is expected that the mosquito density in Shanghai this year will reach the peak of the whole year in mid-to-late June.
Although there are many ready-made mosquito repellent methods, many people feel that spraying insecticides and lighting mosquito coils is not safe enough, or that it is too laborious to wield electric mosquitoes to shoot. With pure natural, safe, worry-free and other selling points, various colors of "mosquito repellent grass" have successfully attracted a large number of consumers.
But can these "mosquito repellent grasses" really get people rid of mosquito troubles?
The reporter interviewed experts from Shanghai Botanical Garden and Shanghai Chenshan Botanical Garden, who pointed out that most of the plants labeled "repellent mosquitoes" may not be as "god" as the merchants say, whether there is an effect depends on the actual situation, do not have too many expectations after purchase.
On June 14, the reporter entered "mosquito repellent grass" on a shopping website, and the reporter queried more than 4,000 results. One of the best merchants sold more than 30,000 pots of "mosquito repellent grass" a month.
Look closely at these "mosquito repellent grasses", there are two main types.
One is plants with strong aromas, such as evening primrose, mint, lemongrass, wattle, basil, rosemary, marigold and so on. They emit some pungent odors.
The other is plants that can prey on insects, such as flytraps, nepenthes, etc. They can synthesize attractive substances, such as honeydew, induce mosquitoes to come and feed, and then catch them in one fell swoop.
Experts pointed out that most of the plants with strong aroma are vanilla plants, and the geraniol, citronellol, citral and other substances in the body do have a certain role in avoiding insects, and they are also weapons used by plants to defend.
However, whether people can be protected from mosquito bites depends on the distance between these plants and people, the planting density of plants and the growth status.
If you only put a pot of mini-type vanilla plants on the desk, it is impossible to release a sufficient amount of insect repellent odor, and it is even more impossible to let this smell form an "air wall" around the human body.
"You can't talk about mosquito repellent without the dose." Experts said that there are experiments to prove that in the wild, if coated with a concentration of more than 30% citronell, there is indeed a more ideal mosquito repellent effect, but in real life, the mosquito repellent substance emitted by the leaves, its concentration can not reach this level, the mosquito repellent effect is naturally limited.
Take one of the most common "mosquito repellent grasses" on the market at present, geranium, as an example, after its processing can obtain essential oils, in the perfume industry and food industry have an important position, can replace the use of expensive rose essential oil, can also make people avoid mosquito bites, but if in the natural state, the stems, leaves, flowers of geranium can not release a high concentration of aromatic substances like essential oils.
geranium
Many experiments have proved that the mosquito repellent emitted by many plants can only be barely used to protect themselves, and the mosquitoes in the experimental area are still free in addition to not falling on these plants.
In addition, most vanilla plants will release a strong mosquito repellent substance in passive situations, such as being stimulated by mosquitoes to eat and be rubbed. These vanilla plants do not react to mosquitoes that do not nibble on flower leaves. In most cases, it may be naïve to rely on plants to actively release effective mosquito repellent odors.
So, are mosquito-eating plants more reliable?
Experts admit that compared with vanilla plants, the mosquito repellent effect of such insectivorous plants may be worse.
First of all, these plants must first attract mosquitoes close to achieve the purpose of predation, so it is more appropriate to call them "mosquito-attracting plants", and with these plants, the probability of being bitten by mosquitoes is higher.
Secondly, female mosquitoes and other pests that suck human blood do not pay any attention to the "temptation" of carnivorous plants, and they are keen to like people with large body surface area, strong respiratory or physiological metabolism, and easy sweating. At this time, even if a pot of Nepenthes or flytraps is placed between the person and the mosquito, the mosquito will still unswervingly move closer to the person.
【Common "mosquito repellent plants"】
★ Mint
★ Lavender
★ Night incense
★ Basil
★ Nepenthes
Lavender fields
Column Editor-in-Chief: Chen Xisha Title Image Source: Xinhua News Agency
Source: Author: Chen Xisha