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Do mosquitos excrete blood?

Do mosquitos excrete blood?



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Since insects like mosquitos ingest only blood, and insects generally excrete their solid and liquid waste at the same time as frass, I was wondering: is mosquito defecation more like iron pellets or droplets of blood?

I've never seen a mosquito defecate, so I have no evidence. Do they defecate during flight? If so, are tiny little droplets of digested-blood falling from the sky?


When mosquitos feed on blood they release water droplets, this is so they can condense the amount of nutrients from the blood but dispose of the unnecessary water weight. This act of releasing excess water is often mistaken as 'pooping', a clearer view of the process here. Actual footage of fecal excretion however, is harder to come across.

Mosquito defecation is more like iron pellets, to maximize their meals they excrete water during or after feeding (in case they need to make a quick get away). Iron is toxic in high doses, so the mosquito excretes it after absorbing the nutrients in the blood, resulting in dark pellets, containing iron and uric acid.


Blood-sucking mosquitoes keep their cool

No one likes being bitten by whining mosquitoes, but have you ever considered what the experience is like for them as their cold-blooded bodies fill with our warm blood? Now researchers reporting online on December 15 in Current Biology, a Cell Press publication, have uncovered the mosquitoes' secret to avoiding heat stress: they give up cooling droplets of their hard-won meals.

The study shows for the first time that blood-feeding insects are capable of controlling their body temperature, the researchers say.

"During feeding on a warm-blooded host, such as a human being, mosquitoes ingest quite a large amount of hot blood in a short period of time," said Claudio Lazzari of Université François Rabelais. "We aimed to determine to what extent these insects are exposed to the risk of overheating during the blood intake."

Mosquitoes have to be quick, lest their host turns into a potential predator, Lazzari points out. But that influx of heat could send their internal body temperature soaring past physiological limits.

Insects' body temperatures generally do depend on the environment around them. However, earlier studies have shown that insects, including bees and aphids, can control their temperature with beads of nectar or sap. Mosquitoes, too, will give up drops of fluid during feeding.

"What intrigued us was why they eliminate fresh blood, which is a precious and risky-to-obtain nutritive element," Lazzari said.

To find out, he and Chloé Lahondère used a camera that depends on heat to form images, much as a regular camera depends on light. Those images highlighted differences in temperature between the body parts of mosquitoes as they fed. Their heads reached temperatures close to that of the ingested blood, while the rest of their bodies remained closer to ambient temperature. That temperature variation wasn't observed when mosquitoes dined on sugar water instead.

The researchers showed that the cooling depended on those drops of fluid the insects excrete from their backsides as they feed. Lazzari and Lahondère say that the mosquitoes' strategy no doubt protects them and any malaria-causing (Plasmodium) parasites they might be carrying. The new understanding of mosquito physiology is more than a curiosity it could lead to strategies aimed to control mosquitoes and the diseases they spread.

"Blocking or delaying the production of the excreted fluid would have a double impact on the physiology of mosquitoes: on water and thermal balance," Lazzari said. "Indirectly, this would affect microorganisms transmitted by insects by modifying the thermal environment to which they are exposed."


They Have a Preference for Blood Type O

Mosquitoes live to bite humans and I&aposm pretty sure they think they are doing it for a good reason: They rely on human blood to reproduce. Unfortunately, about a million people die each year from mosquito bites, so if there are ways you can avoid them, by all means, do so. Hopefully, this article will enlighten you if you have ever wondered why these pests bite some people much more than others.

One of the reasons is their preference for one blood type over all others.

The Top Three Blood Types That Mosquitoes Prefer:

  • Type O: Studies have shown that mosquitoes prefer this blood type over and above all others.
  • Type B: Type B is the next popular blood type for these pests.
  • Type A: Apparently Type A is the least popular of the top three blood types and those of you who have it are about half as likely to be bitten as those with Type O.

A Hope-Raising Prediction

Jeff Riffell, an associate biology professor at the University of Washington, predicted recently that in the next 10 years, scientists would be capable of developing a variety of methods to keep humans from being bitten by mosquitoes.

This illustrates why it is hard to tell a male from a female mosquito, although the female is the one that you actually hear making that buzzing noise.


Do mosquitos excrete blood? - Biology

Being a mosquito can really suck. Not only do you have to gulp down your food because your dinner can turn around and swat you if you&rsquore not fast enough, but a bellyful of hot blood can really do a number on your little body, which prefers to keep things cool.

So how do feeding skeeters keep from overheating? They take advantage of evaporation. That&rsquos according to a study in the journal Current Biology. [Chloé Lahondère and Claudio R. Lazzari, "Mosquitoes Cool Down during Blood Feeding to Avoid Overheating"]

Insects depend on the environment to regulate their body temperatures. But too much heat can be bad for their health. That&rsquos a serious problem when your meals consist of hot, fresh animal blood. The solution, it seems, is to use a drop of your dinner to cool you down. Like sweat, only blood.

Scientists used a thermal camera to watch mosquitos eat. And they found that mosquitoes that excrete, and then hang onto, a single bead of blood while feeding have bodies a couple degrees cooler than those that don&rsquot.

Disrupting this sacrificial blood cooling system could provide a new strategy for controlling mosquitoes, and the diseases they spread. Because if a skeeter can&rsquot secrete, its next supper could be its last.


Do mosquitos excrete blood? - Biology

Temperature is one of the most important factors affecting the life of insects [1]. For instance, high temperatures can have deleterious effects on insects' physiology. Therefore, many of them have developed various strategies to avoid the risk of thermal stress [2]. They can seek a fresher environment or adjust their water loss, but hematophagous insects, such as mosquitoes, must confront the issue of thermal stress at each feeding event on a warm-blooded host [3]. To better understand to what extent mosquitoes are exposed to thermal stress while feeding, we conducted a real-time infrared thermographic analysis of mosquitoes' body temperature during feeding on both warm blood and sugar solution. First, our results highlighted differences in temperature between the body parts of the mosquito (i.e., heterothermy) during blood intake, but not during sugar meals. We also found that anopheline mosquitoes can decrease their body temperature during blood feeding thanks to evaporative cooling of fluid droplets, which are excreted and maintained at the end of the abdomen. This mechanism protects the insect itself, probably as well as the sheltered microorganisms, both symbionts and parasites, from thermal stress. These findings constitute the first evidence of thermoregulation among hematophagous insects and explain the paradox of fresh blood excretion during feeding.

Highlights

► During blood feeding, mosquitoes face the problem of avoiding overheating ► Neither heterothermy nor evaporative cooling occur in males or sugar-feeding females ► Anophelines perform evaporative cooling during blood feeding ► This constitutes the first report of thermoregulation in hematophagous insects


Researchers Put The Bite On Mosquitoes

Few things sting like a mosquito's bite--especially if that bite carries a disease such as malaria, yellow fever, Dengue fever or West Nile virus. But if researchers from The University of Arizona in Tucson have their way, one day mosquito bites may prove deadly to the mosquitoes as well.

"Our goal is to turn the female mosquito's blood meal into the last meal she ever eats," said project leader Roger L. Miesfeld, a professor of biochemistry and molecular biophysics in UA's College of Science and a member of BIO5 and the Arizona Cancer Center.

Other UA researchers involved with the project include Patricia Y. Scaraffia, Guanhong Tan, Jun Isoe, BIO5 member Vicki H. Wysocki, and the late Michael A. Wells.

These researchers have discovered that one particular mosquito species, Aedes aegypti, has a surprisingly complex metabolic pathway, one that requires its members to excrete toxic nitrogen after gorging on human blood. If the mosquitoes fail to do so, they'll also fail to lay eggs--and will likely sicken and die.

Scaraffia, a research assistant professor in UA's department of biochemistry and molecular biophysics, and the other members of the team published their findings in the January 15 issue of the Proceedings of the National Academy of Sciences. The research was funded by the National Institutes of Health.

Miesfeld and his colleagues are seeking a molecule that is harmless to humans, but will gum up the works of mosquito metabolism, forcing the mosquitoes to hang onto the nitrogen. Such a molecule would kill both the mosquitoes and their would-be progeny--thus slowing the spread of disease.

Once found, this molecule--and similar molecules aimed at other mosquito species--could be developed into an insecticide and sprayed in places where mosquitoes congregate, such as around water and on mosquito netting.

The researchers also envision developing an oral insecticide--a mosquito-slaying pill that members of a community with a high instance of, say, yellow fever or malaria might take to reduce the mosquito population. The pill wouldn't be a vaccine if people who took it were later bitten by a disease-carrying mosquito, they would still become infected. However, the mosquito would ingest the insecticide along with the blood, causing her to bear fewer young and possibly die before she could bite anyone else.

"The whole community would essentially become one big mosquito trap," Miesfeld said. Over time, mosquito populations and disease rates would both decline. "It would be a group effort that in the long run could have a huge impact."

In a world where both mosquitoes and the diseases they carry are becoming increasingly resistant to known insecticides and medicines, finding new ways to fight them is crucial.

"This would be one more weapon in our arsenal against diseases that kill millions of people a year," Miesfeld said.

Story Source:

Materials provided by University of Arizona. Note: Content may be edited for style and length.


Moveable Feasts

It starts with sight. From a distance, mosquitos latch onto movement and dark colors, likely because they contrast with static, lighter surroundings. So stow your black and blue shirts for the summer and learn to be less fidgety, because beyond here you’re mostly at the mercy of your inescapable genetics.

As a mosquito buzzes toward a potential victim, its nose takes over — or, rather, its maxillary palp , an organ with receptors that help it home in on carbon dioxide from as far as 150 feet away. “They follow a CO2 trail like a shark follows a blood trail,” Conlon says. “They kind of zigzag along it.” And since we all emit the gas when we breathe, they’ve got us pretty well cornered on this front .

But some are more vulnerable than others. Large people and pregnant women (fitting, considering female mosquitoes only take our blood to produce eggs) generally have higher metabolic rates, which means more carbon dioxide output to lure in the bugs. Exercise has the same effect.

Besides CO2, the human body exudes somewhere in the realm of 400 other compounds, many of which mosquitos can also sense. As Conlon puts it, “some of them are attractive and some are repellant,” and it’s virtually impossible to determine which combinations signal the best meal.

“Everybody’s excretory cocktail is going to be different,” says William Kern, Jr., associate professor of entomology and nematology at the University of Florida’s Fort Lauderdale Research and Education Center. “So the compounds you excrete through your skin and breath are different.”

Scientists have pinpointed some scents that mosquitoes seem to find irresistible, though, and unfortunately we have little control over them. People who have the bad luck to produce excess amounts of lactic acid, uric acid and ammonia, for example, are walking delicacies.

Some of the alluring aromas come from sweat, and one study indicates that alcohol might play a role in attracting mosquitos as well. A beer on the porch after your evening run might very well be an “Open for Biting” sign.

Skin bacteria also play a large role in body odor, and studies have shown that different species of mosquito are more attracted to different parts of the body . Some opt for the head and shoulders, perhaps because of the higher carbon dioxide concentration, while others prefer feet and ankles. One researcher found that Aedes aegypti , a common tropical disease vector, has a taste for his dirty socks .


Question Why do mosquitoes bite me and not my friend?

Recent evidence suggests that some people give off masking odors that prevent mosquitoes from finding them.

Known as a vector for the West Nile virus, this Culex quinquefasciatus mosquito has landed on a human finger, in order to obtain its sustaining meal of blood from its host. James Gathany, CDC photographer, 2003. Public Health Image Library, Centers for Disease Control and Prevention.

Recently, scientists at Rothamsted Research in the UK discovered that some people produce chemicals that smell bad to mosquitoes, masking the chemicals that usually attract the mosquitoes.

Fed alive to mosquitoes. Washington, D.C., April 24. One of the unsung heroes of the government service is Carroll Smith, research expert in equine fever in the Bureau of Entomology, Department of Agriculture, who since 1927 has allowed himself to be fed alive to a horde of mosquitoes. Harris & Ewing, photographers, 1937. Prints & Photographs Division, Library of Congress.

James Logan and John Pickett (Vince, 2006) devised some unique ways of testing body odor. First, they had two different people put one hand into each end of a chamber and the investigators watched which hand the mosquitoes preferred. Then they selected the person who was not preferred (who felt lucky up to this point) and sealed their body in foil to collect their sweat. Talk about an unpleasant experiment. The researchers set about analyzing the body chemicals and are now waiting to patent the results in hopes of producing a natural insect repellent.

Just a few Bugs: Mosquitoes aren’t a big deal in June and July but ONLY if you remember to wear bug jackets, head nets, or choose to use insect repellent. Mosquitoes swarm around a hiker in a white jacket. Kobuk Valley National Park, 2009. National Park Service photograph, NP Gallery Digital Asset Management System.

The female mosquito is the one that bites (males feed on flower nectar). She requires blood to produce eggs. Her mouthparts are constructed so that they pierce the skin, literally sucking the blood out. Her saliva lubricates the opening. It’s the saliva plus the injury to the skin that creates the stinging and irritation we associate with mosquito bites.


Where Mosquitos Breed. Bain News Service, between 1915 and 1920. Prints & Photographs Division, Library of Congress.

Unfortunately, mosquitoes are carriers for a host of diseases, including malaria, yellow fever, West Nile virus, and Dengue fever. There are hundreds of species of mosquitoes belonging to the family Culicidae. Since they breed in standing water, a way to eliminate them around the home is to remove objects where water collects, such as cans, buckets, old tires, and refreshing the water in bird baths at least once a week. Turn water barrels upside down during the winter, as well.

Insect repellents often contain DEET (N,N-diethyl-meta-toluamide) although there are more natural ingredients available, such as eucalyptus oil extract. You can try to limit your exposure to mosquitoes when outdoors by using a fan or by covering exposed skin with light colored clothing and a hat. Mosquitoes tend to be more of a problem from dusk to dawn.

Mosquito Netting Hat, Noatak National Preserve, 2016. National Park Service photograph, NP Gallery.

Published: 11/19/2019. Author: Science Reference Section, Library of Congress


Mosquitoes. What Are They Good For?

NPR's Ari Shapiro speaks with Nora Besansky, a professor of biology specializing in mosquitoes, about what would happen if mosquitoes were eradicated.

We've spent a lot of time lately talking about the devastating impacts of Zika, a disease that is spread by mosquitoes. Those little buzzing insects can also be blamed for dengue fever, West Nile virus, malaria and lots of other horrible afflictions, not to mention their tendency to ruin picnics. So we wondered, is there anything good about mosquitoes? To find out, we have reached Professor Nora Besansky on Skype. She is a mosquito expert at Notre Dame University.

NORA BESANSKY: Hi. How are you?

SHAPIRO: Great. So are mosquitoes good for anything?

BESANSKY: Yes, they're good for lots of things. For what it's worth, only about a hundred - less than a hundred species transmit those horrible diseases that you've referred to out of thousands of species that live on every continent except Antarctica. And what those mosquitoes are good for, they're food for fish and other insect predators and birds. They pollinate plants.

SHAPIRO: Wait - they're pollinators? Really? I knew they were food, but, they're pollinators?

BESANSKY: Yes, indeed. And, you know, it's only the males that take a blood meal from their hosts, and often those hosts have nothing to do with humans. So there are mosquitoes that feed on snakes, frogs, birds. Only less than a hundred are a problem for humans.

SHAPIRO: Let me just play devil's advocate here. Is there anything that only eats mosquitoes, or if the mosquitoes disappeared, could the birds and the fish and the predatory insects and things just eat other things?

BESANSKY: Wow. That's a pretty good question. I wouldn't want to guess the consequences of eradicating all 3,500 or 4,000 species of mosquitoes. What I do feel comfortable saying is that if we target only a single species that's the most important transmitter of, let's say, malaria in the world then I feel pretty comfortable saying it would only have good consequences. (Laughter).

SHAPIRO: So we might not want to get rid of all 3,500 or 4,000 species of mosquito, but if, for example, we get rid of the Aedes Aegypti, which is the species that carries the Zika virus, you'd be OK with that?

BESANSKY: I think that would be a very good outcome, yes.

SHAPIRO: I know that generally scientists try not to place a value judgment on an entire species, but did I just hear you say that the Aedes Aegypti mosquito is a bad species? We can just stamp it with that label and get rid of it if possible?

BESANSKY: Yes, you did hear me say that.

BESANSKY: You know, let's put this in perspective, shall we? The human race has probably been responsible - unknowingly, inadvertently - in eliminating hundreds of thousands of species, mainly rain forest ones, by destroying their habitats. So in perspective here, we're talking about a single species of mosquito that's responsible for quite a lot of disease transmission and suffering in the world. I think - there you go. No, I don't feel bad about saying we should get rid of that one species.

SHAPIRO: That is biology professor and mosquito expert Nora Besansky speaking with us from Notre Dame University. Thank you very much.

BESANSKY: (Laughter). Thank you.

[POST-BROADCAST CORRECTION: In the original audio version of this story, Professor Besansky said only male mosquitoes take a blood meal from their hosts. In fact, it's females mosquitoes that take the blood meal.]

Copyright © 2016 NPR. All rights reserved. Visit our website terms of use and permissions pages at www.npr.org for further information.

NPR transcripts are created on a rush deadline by Verb8tm, Inc., an NPR contractor, and produced using a proprietary transcription process developed with NPR. This text may not be in its final form and may be updated or revised in the future. Accuracy and availability may vary. The authoritative record of NPR&rsquos programming is the audio record.

Correction Feb. 20, 2016

In this story, Nora Besansky says only male mosquitoes take a blood meal from their hosts. In fact, it's female mosquitoes that take the blood meal.


Blood-sucking mosquitoes keep their cool

The mosquito performs evaporative cooling. The retention of the fluid drop attached to the abdomen end leads to a fall of the abdomen temperature causing a clear temperature gradient along the mosquito body. N.B., the color of the droplet does not reflect the real temperature, because of the difference in the emissivity between the cuticle of the mosquito and the drop surface. Credit: Lahondčre et al. Current Biology

No one likes being bitten by whining mosquitoes, but have you ever considered what the experience is like for them as their cold-blooded bodies fill with our warm blood? Now researchers reporting online on December 15 in Current Biology have uncovered the mosquitoes' secret to avoiding heat stress: they give up cooling droplets of their hard-won meals.

The study shows for the first time that blood-feeding insects are capable of controlling their body temperature, the researchers say.

"During feeding on a warm-blooded host, such as a human being, mosquitoes ingest quite a large amount of hot blood in a short period of time," said Claudio Lazzari of Université François Rabelais. "We aimed to determine to what extent these insects are exposed to the risk of overheating during the blood intake."

Mosquitoes have to be quick, lest their host turns into a potential predator, Lazzari points out. But that influx of heat could send their internal body temperature soaring past physiological limits.

Insects' body temperatures generally do depend on the environment around them. However, earlier studies have shown that insects, including bees and aphids, can control their temperature with beads of nectar or sap. Mosquitoes, too, will give up drops of fluid during feeding.

"What intrigued us was why they eliminate fresh blood, which is a precious and risky-to-obtain nutritive element," Lazzari said.

To find out, he and Chloé Lahondère used a camera that depends on heat to form images, much as a regular camera depends on light. Those images highlighted differences in temperature between the body parts of mosquitoes as they fed. Their heads reached temperatures close to that of the ingested blood, while the rest of their bodies remained closer to ambient temperature. That temperature variation wasn't observed when mosquitoes dined on sugar water instead.

The researchers showed that the cooling depended on those drops of fluid the insects excrete from their backsides as they feed. Lazzari and Lahondère say that the mosquitoes' strategy no doubt protects them and any malaria-causing (Plasmodium) parasites they might be carrying. The new understanding of mosquito physiology is more than a curiosity it could lead to strategies aimed to control mosquitoes and the diseases they spread.

"Blocking or delaying the production of the excreted fluid would have a double impact on the physiology of mosquitoes: on water and thermal balance," Lazzari said. "Indirectly, this would affect microorganisms transmitted by insects by modifying the thermal environment to which they are exposed."


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