*Editor’s note: K-VIBE invites experts from various K-culture sectors to share their extraordinary discovery about the Korean culture.
[Larger Than Architecture] Chapter 1. This World We Live In
Ep. 1. The Season of Mosquitoes
By Kim Won (Master K-architect)
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I fear mosquitoes more than anything else in the world. When a mosquito buzzes around my head on a midsummer night, it keeps me awake all night, leaving me sleep-deprived and lethargic the next day. This often results in poorly handled important tasks, sometimes leading to disastrous outcomes.
Yet, for some reason, mosquitoes seem to particularly favor me. Even in a group, I am the one who gets bitten, suffering from prolonged itching and marks. What baffles me more is that these pests ignore my wife completely and relentlessly target only me. Various theories abound – I sweat too much, I don't wash enough, my blood is too sweet, my blood pressure is high, my body is too warm – but without knowing the exact reason, I feel utterly wronged.
People laugh when I say mosquitoes are my greatest fear. However, for me, this is a stark reality and an undeniable fact. Mosquitoes, which weigh just 3 milligrams, are terrifying not only to me but also potentially to even the mightiest of people. Recent theories suggest that Alexander the Great’s death at the age of 32 in 323 BC was not due to poisoning but to a malaria-carrying mosquito. This theory gains credibility from historical records that Alexander inspected the swamps near Babylon two weeks before his death, an area still rife with malaria, which has an incubation period of 9 to 14 days.
Autopsies of mummies in Egypt revealed that some pharaohs had swollen spleens due to malaria. Some scholars also believe Genghis Khan died from malaria, which is plausible. The list of historical figures who succumbed to mosquito-borne diseases includes popes, European kings, Roman emperors, Mother Teresa, Dante, and Saint Augustine.
Cesare Borgia, the ambitious son of Pope Alexander VI, dreamed of unifying Italy, but his father's death from malaria thwarted his plans, altering Italian history and, consequently, world history. Mosquitoes almost halted the construction of the Panama Canal as well. When the French began construction in 1881, most workers lived in open huts, unaware that mosquitoes transmitted diseases, leading to over 1,200 workers dying from malaria by 1884, causing construction to stop. When the U.S. resumed the project in 1904, they prioritized mosquito control, completing the canal in 14 years.
In another instance, mosquitoes changed a nation's destiny. Haiti, originally known as "Hispaniola" under Spanish rule, saw its native population decimated by smallpox brought by Europeans. To compensate, African slaves were brought in to work on sugar plantations, eventually outnumbering Europeans. Inspired by the French Revolution of 1789, the slaves revolted, seeking "liberty, equality, and fraternity." France sent troops from its Louisiana territory to quell the rebellion, but upon arrival, they succumbed to yellow fever, a deadly disease spread by mosquitoes, leading to Haiti's independence in 1804.
In 2008, 247 million people worldwide contracted malaria, resulting in 2 to 3 million deaths. In 2009, 780,000 died from the disease. By 2010, 219 million cases were reported with 660,000 fatalities. In 2014, 755,000 people died from malaria. Adding cases of encephalitis, dengue fever, and other mosquito-borne diseases, the annual toll reaches 700 million infections and 2 million deaths, according to WHO statistics. Most victims are African children, with one child dying every minute. Malaria affects 99 countries, including South Korea, making mosquitoes "the most dangerous animal on Earth." Each year, around 4,000 Koreans contract malaria. Japanese encephalitis mosquitoes are even more feared, with 1,772 malaria cases and 26 Japanese encephalitis cases in 2010. Globally, there are 3,150 mosquito species, 56 of which inhabit Korea.
Mosquitoes are primarily herbivores, subsisting mainly on plant sap, fruit juices, and dew. Typically, they store plant-derived sugars in three paired diverticula located on their backs and abdomens. However, they have a dual system, using their stomachs to store blood when they feed. Female mosquitoes turn into bloodsuckers after mating to obtain the necessary proteins for developing fertilized eggs, a behavior that can be described as quite macabre. To ensure that blood flows smoothly without clotting, mosquitoes insert a dual-structured proboscis into their host's blood vessels. The inner tube draws blood, while the outer tube injects an anticoagulant produced by the mosquito, preventing blood clotting.
The Plasmodium parasite, the cause of malaria, is transmitted this way. It infects red blood cells, multiplying and eventually destroying them, leading to high fevers over 40 degrees Celsius and, potentially, death. Similarly, encephalitis is transmitted by mosquitoes. The red house mosquito, which spreads Japanese encephalitis, is particularly deadly to infants, underscoring the fearsome nature of these insects.
Today, mosquitoes have developed resistance to almost all insecticides, including DDT, due to prolonged human usage. This has rendered common insecticides ineffective, leading to stronger chemicals being developed, which are often more harmful to humans than mosquitoes. Additionally, due to global warming and advancements in heating technology, mosquitoes can survive through winter, living longer and attacking more frequently, not just in summer but year-round. They attack not only humans but also animals like dogs, cattle, horses, and pigs. Those who have seen a swarm of mosquitoes torment a large cow understand the formidable power of these tiny creatures. With their slender proboscis, they penetrate the tough hide of large animals, transmitting heartworms that grow and proliferate within the host, eventually leading to death. Watching the heart of a cow filled with wriggling parasites on TV convinced me that mosquitoes are indeed the most terrifying creatures.
Historically, the cause of malaria was misunderstood, believed to be transmitted through the air rather than through blood. The term "malaria" itself combines the Latin "mal-" (meaning "bad") and "aria" (meaning "air"), originating from the belief that the disease was caused by bad air. The term "mosquito" comes from the Spanish word for "little fly" ("mosca" with the diminutive "-ito").
Despite the seemingly innocuous name "little fly," mosquitoes should not be underestimated. People often think that screens and mosquito nets will keep mosquitoes out, but that's a misconception. Mosquitoes can detect chemical substances released by humans when they move or breathe. They can sense carbon dioxide from 10 meters away and lactic acid from 20 meters away. Once they detect these signals, they persistently explore and find even the tiniest opening to enter. Therefore, mosquito nets must be flawless, without even a millimeter of an opening, to effectively block these persistent intruders.
This year, with over four million cattle and pigs culled nationwide due to foot-and-mouth disease, mosquitoes may turn more aggressively towards humans if their population remains constant. According to Andrew Spielman, a former Harvard professor and malaria expert, in his book "Mosquito: A Natural History of Our Most Persistent and Deadly Foe," mosquitoes are indeed our most tenacious and deadly adversaries.
While mosquitoes are primarily herbivores, female mosquitoes switch to bloodsucking after mating to obtain proteins necessary for egg development. They generally prefer large animals like cattle and pigs but will also attack humans and spread diseases. The Anopheles mosquito transmits malaria, while the Aedes aegypti spreads yellow fever and dengue fever.
Mosquitoes exhibit a highly sophisticated blood-sucking process. Initially, they secrete saliva through a small duct (salivary duct) that dissolves fats on the skin, softening it for easier penetration. The mosquito’s saliva contains anticoagulant properties, preventing the blood from clotting and ensuring a smooth flow. It is during this process that disease-causing parasites and viruses, present in the saliva, enter the human body.
A mosquito can extract approximately 6-9 milligrams of blood in about 90 seconds, which is 2-3 times its body weight. After feeding, it moves to a safe location to digest the blood, a process that takes about 45 minutes. During digestion, the mosquito excretes water in the form of urine, retaining only the nutrients.
The history of mosquitoes dates back much further than that of humans. Fossils from the Cretaceous period, discovered in Canada, date back 79 million years. The prolonged 'war' between humans, who emerged around 2 million years ago, and mosquitoes began much later. Even today, despite advancements such as sending rockets into space, humanity has yet to achieve complete victory over these seemingly insignificant pests.
Several factors contribute to this enduring struggle. Firstly, mosquitoes are extremely prolific. Depending on the species, a female mosquito lays an average of 100-150 eggs at a time, about 3-7 times a month. The eggs hatch into larvae (wrigglers) in two days, become pupae within 1-2 weeks, and emerge as adults 2-3 days later. This results in billions of new mosquitoes daily worldwide.
Humans have employed both offensive (insecticides) and defensive (repellents) strategies against mosquitoes. DDT, once a powerful insecticide, eradicated malaria from regions like East Asia, the US, and Europe, while DEET, a common ingredient in topical mosquito repellents, has been widely used as a shield.
However, mosquitoes’ resilience is remarkable. By the 1950s, DDT-resistant mutant mosquitoes had emerged. Moreover, DDT was banned for being a major ecological disruptor, leading to a resurgence of malaria. Concerns about DEET causing neurotoxicity with prolonged use have also made people more cautious about using it.
Global warming has further complicated matters. According to Professor Park Jae-won of Gachon University, warming temperatures are expanding malaria-prone areas from tropical regions to higher latitudes and altitudes, with the Korean Peninsula being a prime example. Fortunately, the strain of malaria parasite in Korean mosquitoes is less severe and more treatable compared to the tropical strain in African mosquitoes, resulting in relatively fewer fatalities. This summary is based on the insights from Andrew Spielman’s book.
In the summer of 2011, the mosquito population significantly decreased due to persistent rains. The Korea Disease Control and Prevention Agency reported that the number of mosquitoes nationwide by the end of the previous month had decreased by 33.6% compared to the average and by 39.8% compared to the previous year. Specifically, mosquitoes that transmit Japanese encephalitis had decreased by 77.0% compared to the average and by 71.2% compared to the previous year.
The primary reason for the reduced mosquito population was the extended rainy season. Despite the shorter rainy season overall, regions like Seoul experienced daily rainfall from July 7 to 17, surpassing average precipitation levels. Mosquitoes, which have a lifespan of about four weeks, typically engage in mating swarms every 4-5 days during early evenings from the third week of their life. However, this summer, mosquitoes likely spent most of their lives hiding from the rain in grass and behind leaves, rather than engaging in mating swarms.
Experts have observed that many mosquito eggs, laid in sewers and puddles after difficult mating processes, were likely washed away by rising waters during heavy rains. However, it remains uncertain whether this temporary reduction in mosquito populations will last throughout the year. A researcher from the Korea Disease Control and Prevention Agency’s vector-borne disease division stated, "Even if mosquito populations temporarily decrease due to adverse conditions, they quickly return to normal levels when environmental conditions such as temperature and rainfall improve. Once the monsoon season ends and the intense heat begins, mosquito populations could surge rapidly."
Among mosquitoes’ extraordinary abilities, their physical attributes, particularly their attack mechanisms, are noteworthy. They use six piercing mouthparts: one feeding tube on the upper lip, one salivary duct in the lower lip, a pair of saw-like mandibles, and a pair of fine stylets. The most formidable of these, the feeding tube, has a diameter of only 20-30 micrometers, making its penetration into the skin almost imperceptible. Additionally, this tube can bend up to 45 degrees parallel to blood vessels to facilitate easier blood extraction.
Despite weighing only 3 milligrams, a mosquito can ingest blood up to 2-3 times its body weight. Its abdomen expands like an accordion to store the ingested blood, which it later digests, excreting water as urine and retaining nutrients.
Mosquitoes are not only troublesome due to their bites and the resulting prolonged itching. Observing just the female Culex mosquito, we find that with its pair of wings, it can fly at speeds of up to 4.8 kilometers per hour, flapping its wings 250 to 500 times per second, producing a buzzing sound of 500-600 hertz. This incessant noise can deprive important individuals of sleep, potentially affecting significant decisions they must make the following day, illustrating a subtle yet profound impact beyond the physical discomfort of bites.
To combat the deadliest mosquito-borne disease, malaria, countries worldwide are investing in cutting-edge genetically modified (GM) mosquito technology. This includes creating sterile male mosquitoes or flightless female mosquitoes.
Female mosquitoes mate only once before they die, so if they mate with sterile males, they will produce no offspring. Additionally, if female mosquitoes are genetically modified to be unable to fly, they cannot feed on blood, which is essential for egg production.
These innovations represent significant advancements in the fight against mosquito-borne diseases. By reducing mosquito populations and their ability to reproduce, scientists hope to decrease the incidence of diseases such as malaria, dengue fever, and Zika virus, making significant strides toward improved public health globally.
Researchers at Johns Hopkins University have developed a genetically modified (GM) mosquito capable of preventing the malaria parasite from entering its salivary glands. This breakthrough involves altering the mosquito's genes to produce a small protein that blocks the pathway (receptor) the malaria parasite uses to travel from the mosquito's gut to its salivary glands. Consequently, even if an infected female mosquito bites a human, the malaria parasite cannot be transmitted. Similarly, a research team at the University of Maryland reported in the February issue of Science that they have developed a GM fungus with a similar function.
However, the success of these GM organisms depends on their ability to spread within wild mosquito populations. To address this, researchers are leveraging the self-propagating characteristics of the Homing Endonuclease Gene (HEG). By combining the anti-malaria gene with the HEG, they aim to ensure that the beneficial genetic modification spreads widely among wild mosquitoes.
Releasing GM organisms into the wild, whether mosquitoes or fungi, is complex and controversial. In December 2010, Malaysia saw the release of GM mosquitoes, which met significant opposition from environmental and consumer groups concerned about unpredictable ecological consequences.
Despite significant research, one enduring mystery remains: why do mosquitoes seem particularly attracted to me? Researchers at Wageningen University in the Netherlands conducted a study involving 48 volunteers who were instructed to avoid using soap and consuming garlic, onions, peppers, alcohol, and perfumes for 20 hours. They then wore nylon socks to retain their natural foot odor. The mosquitoes were presented with these "experimental materials," revealing that individual body odors, influenced by specific microorganisms on the skin, attract mosquitoes.
The study found that foot odor results from microorganisms converting substances in sweat into volatile compounds. Thus, a person's appeal to mosquitoes depends on the type of bacteria living on their skin. For instance, bacteria from the Pseudomonas genus repel mosquitoes, while those from the Leptotrichia genus attract them. Furthermore, mosquitoes favor skin with fewer but more numerous bacteria rather than a diverse array of bacteria. Therefore, maintaining a clean but microbiologically diverse skin can help reduce mosquito attraction.
When someone persistently expresses their affection towards you, and avoiding it becomes impossible, the best course of action might be to accept it positively, and if possible, gracefully. Instead of viewing it as something unavoidable, it’s more beneficial to see it as an inevitable partnership, a symbiotic relationship.
Now, as I lay inside a small mosquito net, listening to the buzzing outside, I feel content. The buzzing sound is a result of mosquitoes vibrating their wings rapidly during mating. They create this noise to find their mates through resonant wing vibrations.
As the mosquitoes outside become more engrossed in their mating rituals, they buzz louder, and this increases my satisfaction, knowing that the mosquito net temporarily keeps them at bay, allowing me to sleep peacefully. This sense of happiness will last until a pregnant female, driven by the need for protein, manages to breach the net and suck my blood.
This reminds me of my first visit to Parc de la Villette in Paris. I recall seeing a structure that, although it might have represented another creature, appeared to me as a mosquito. Parisians had artistically transformed mosquitoes into charming sculptures, integrating them into the environment and even using them as children's playground equipment. This teaches children to accept natural phenomena as they are.
Mosquitoes are undeniably a part of the ecosystem, playing an essential role in the ecological chain. These tiny creatures have taught me profound lessons. The seemingly trivial mosquito, through its place in the natural world, demonstrates the importance of each component in maintaining the balance of life. (2001. 8. 6)
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1) Genetic Predisposition to Mosquito Bites
Recent studies reveal that mosquitoes do not prefer everyone's blood equally, suggesting a genetic basis for this preference. Professor James Logan of the London School of Hygiene & Tropical Medicine published a study in PLOS ONE highlighting that certain individuals are genetically more susceptible to mosquito bites. By experimenting with 18 pairs of identical twins and 19 pairs of fraternal twins, the study found that identical twins, who share identical genetic makeup, experienced similar numbers of mosquito bites. In contrast, fraternal twins, who share only 50% of their genes, showed a 20-50% difference in bite frequency. This suggests that genes related to body odor play a significant role in mosquito attraction.
Mosquitoes discern their preferred human hosts through specialized structures called maxillary palps, functioning like olfactory organs. These structures enable mosquitoes to detect human odors such as those from worn socks, used clothes, or bed sheets. Additionally, mosquitoes can sense carbon dioxide, which is exhaled in higher amounts by pregnant women, larger individuals, and those who have consumed alcohol or just exercised.
2) Initiatives to Eradicate Harmful Mosquitoes
In a more proactive approach, some countries are intensifying efforts to eradicate harmful mosquitoes through genetic modification. Florida, USA, is considering deploying GM mosquitoes developed by the University of Florida. Brazil has already been releasing GM mosquitoes since last year to reduce mosquito populations by preventing successful reproduction.
Two primary methods are employed in creating GM mosquitoes. The first involves altering the genes responsible for the survival of male mosquitoes, rendering them unable to reproduce effectively. These modified males mate with wild females, but the resulting offspring die before reaching maturity. The second method uses tetracycline, an antibiotic. GM male mosquitoes require tetracycline to survive; without it, they and their offspring perish soon after hatching.
The effectiveness of these GM mosquitoes has been demonstrated. A six-month experiment by the University of Florida saw a 96% reduction in the local mosquito population after releasing 3.3 million GM mosquitoes. Despite these promising results, concerns remain about the broader ecological impacts. Mosquitoes, though a nuisance to humans, are a crucial food source for bats and some bird species. There are also worries about potential adverse effects on animals consuming GM mosquitoes, necessitating careful consideration and monitoring.
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