The "oil" on the car seat is actually sweet. If you don't believe it, try it.

Recently, a large number of Beijing workers have started working from home. The residential communities and parking spaces that were once empty on weekdays are now filled with people and cars.

So, a new problem arose. Starting from some day, the cars downstairs were "splashed with oil" for no reason, especially the vehicles parked under the trees, which were in a terrible state (luckily, Tadpole did not have this trouble, guess why).

Netizens said: The happiest thing at the moment is to own an underground parking space!

Few cars were spared. Image source: Tadpole Jun

Can't bear to look directly at, picture source: Tadpole Jun

Take a closer look, it's slimy. Image source: Tadpole Jun

Not only that, shared bicycles also did not escape the bad luck. Image source: Netizen Huzhou Ancient Bridge

So, what happened to these cars?

Image source: Weibo

Some time ago, private cars in Wuhan also suffered a wave of "baptism". After experts "solved the case", it was found that the culprits were aphids the size of sesame seeds!

People who like to grow flowers should be familiar with aphids. They are typical "plant killers" that like to suck the sap of plants. Street trees such as Sophora japonica, willow, sycamore, and Koelreuteria paniculata are easily attacked by aphids.

As aphids continue to eat and drink, they also constantly excrete droplets of excrement from their buttocks. These droplets are called honeydew.

Aphid honeydew. Image source: thedailygarden

Due to the large number of aphids, honeydew sometimes falls from the trees like rain. This is why when you walk under the trees in spring and summer, "raindrops" will occasionally drip on your face. Congratulations, you have been successfully hit by "urine".

Since then, the truth behind the incidents of private cars and shared bicycles being splashed with oil has finally come to light.

Honeydew: Aphids' biological weapon

The name of honey dew just sounds sweet~

Aphids absorb the amino acids they need from the phloem sap of plants when they feed on it, but many plant sap contains low levels of amino acids and high levels of sugar, so in order to balance their own nutritional needs, aphids have to excrete excess sugar-rich fluids through the rectum.

Look closely at this needle-like mouth, which is how aphids suck juice. Image source: Insects in City

Honeydew is basically derived from the phloem sap of the host plant. Its main component is sucrose, and sugar accounts for 80% of the dry weight of the honeydew.

After the juice is absorbed by aphids, the types and relative amounts of sugars in the intestine will change. On the one hand, the sugars in the juice will be hydrolyzed by enzymes in the intestine, such as sucrose and maltose being broken down into glucose and fructose; on the other hand, some complex trisaccharides and disaccharides will be synthesized in the corresponding cells, such as melezitose, raffinose, pyranosyl glucoside and trehalose.

In 2007, Hogervorst et al. compared the chemical composition of three types of honeydew from aphids raised on potatoes and wheat and found that all three types of honeydew contained large amounts of sucrose and its decomposition products, glucose and fructose.

To sum it up in one word: sweet!

It is said that it is one hundred and fifty times sweeter than sugar, no wonder ants like to drink it so much.

Ant's Fat House Happy Water, Image Source: See Watermark

In 1980, Chinese researchers found that the amount of nectar produced by an aphid in its lifetime is 2,220 micrograms, which is 90 times the weight of a young aphid (25 micrograms) and 7 times the weight of an adult aphid (320 micrograms). The frequency and intensity of nectar production are highest during the nymph stage.

Interestingly, both early studies and studies around 2020 have shown that people's defecation also depends on time and temperature. They excrete more honey during the day than at night, and the amount of honey is larger. It is easier to excrete honey when the temperature is between 18-30°, and it is most active around 18℃.

It seems that aphids are also afraid of heat, so can their sweet water be contained in midsummer? Theoretically, yes.

Aphids are so sweet, would they be delicious?

According to people who have eaten aphids, aphids are not very sweet when eaten individually, but have a light fragrance. Eating a handful is probably enough.

So, next time you go out and feel hungry or tired, why not try licking it a couple of times?

Of course, honeydew is not exclusive to aphids. Some scale insects, psyllids, and butterflies also secrete honeydew.

What makes aphids master the traffic code

What is the origin of this tiny aphid that is so annoying...

In taxonomy, aphids belong to the order Hemiptera, suborder Sternorhynchorhynchus. Some books still use the traditional taxonomy system. For example, in General Entomology, aphids still belong to the order Homoptera (now there is no such concept as Homoptera). In short, the order Hemiptera includes the two major insects we are familiar with, stink bugs (stinky bugs) and cicadas (cicadas), as well as the scale insects, which are the closest relatives of aphids. They are a stubborn natural enemy of plants. I believe that many people who have raised flowers have dealt with them.

Tiny just isn't that cute

There are many types of aphids, with more than 4,700 species in the world and more than 1,000 species in my country alone. As a representative of herbivorous insects, aphids are often treated as "pests" for prevention and control. Most aphids have a very monotonous diet and only eat the same plant. A small number of aphids feed on multiple plants.

Gospel of Secret Horror

Broccoli infested by aphids is unrecognizable. Image source: Wikipedia

Why are there so many tiny aphids?

We know that most insects can only produce offspring after mating between females and males, while some insects can reproduce parthenogenetically (parthenogenesis: the phenomenon that insects can develop new individuals without fertilization) and give birth to young animals directly, which is not uncommon in the insect world. Aphids have both of these features, which really means that "aphids are small but have all the functions."

To put it bluntly, the mother aphids do not need to mate and can directly give birth to baby aphids (this saves so many steps, no wonder there are so many of them).

Of course, not all aphids do this, and different species have different reproductive strategies. Some only reproduce parthenogenetically throughout their lives, so the aphids they give birth to are usually female individuals; some aphids perform parthenogenesis and sexual reproduction alternately, so these aphids have to give birth to both male and female aphids when they need sexual reproduction, preparing for the next step of mating and reproduction.

Parthenogenesis, you will understand after reading this cartoon, Image source: Entomology Uncensored

Some people may wonder: Since parthenogenesis can master the traffic code, why do some species still have to mate and reproduce?

In fact, there are only a few species that reproduce parthenogenetically throughout their lives, and the same type of aphids have different survival strategies in different countries and regions. For example, the citrus aphid reproduces parthenogenetically in many places, but in Japan, there are populations that reproduce sexually.

Come and feel the power of life

There are more species that alternate between parthenogenesis and sexual reproduction. Because sexual reproduction requires time to lay eggs and hatch, this can greatly reduce the growth rate of aphids when the temperature drops and food is scarce, and it is easier for them to overwinter in the form of eggs. In other words, once the temperature drops sharply, adult aphids are more likely to suffer large-scale deaths, and switching reproductive methods is a simple and feasible solution (humans can only dream of it).

Are so many aphids harmful to humans and animals?

Although aphids "harm" plants, they are almost harmless to humans and animals.

However, because they are indeed too numerous and extremely destructive to plants, they are prone to cause sooty mold (also known as sooty mold, which is mostly spread by aphids, scale insects, etc., and mainly harms the leaves of plants, but can also harm tender branches and shoots.), and have become one of the key targets of garden pest control. The community where Tadpole Jun lives has carried out three rounds of pest control since the beginning of summer...

Plants infected with sooty mold look black. Image source: tylerpaper

At the same time, aphids are also a key target of agricultural prevention and control. For example, cotton aphids can cause cotton fiber pollution, leading to reduced cotton production and causing huge economic losses. There are also pea aphids that are widely distributed in my country. The large amount of honeydew they secrete covers the surface of crops, seriously affecting the photosynthesis and respiration of crops.

The greening maintenance team of the Bureau of Landscape Architecture is spraying pesticides on the tree crowns to eliminate insects. Image source: Yangtze River Daily

So, what should we do with vehicles that have been "attacked" by aphids?

The owner of the car wash shop suggested: Car owners should try not to clean these stains by themselves. First, because it is sticky, it is difficult to wipe it off with paper or dry cloth. If it has dried up, wiping it hard may affect the paint of the car. Second, it is recommended that car owners avoid parking under trees in spring and summer, otherwise they will have to wash the car every two or three days.

Tadpole thinks that instead of struggling to find a parking space, it is better to give the car a disposable raincoat.

The universal tb

Finally, Tadpole still needs to realize that the earth does not belong to us humans alone, and we must learn to accept the existence of other life.

Review expert: He Jiale, project officer of WWF Northeast Resident Working Group.

END

Tadpole Musical Notation original article, please indicate the source when reprinting

Editor/My Neighbor Totoro