Tag Archives: mosquitoes

Poinsettia frogs and a Merry 2023 Christmas

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I stumbled across this image in a December 20, 2023 article by Dorothy Woodend for The Tyee where she is the culture editor,

Instead of new material goods this holiday season, I’m searching for something more elusive and ultimately sustaining. And it may help us grow our appreciation for the natural world and its mysteries. Illustrations for The Tyee by Dorothy Woodend.

À propos given the name for this blog and the time of year. Thank you, Ms. Woodend!

I try not to do too many of these stories since the focus for this blog is new and emerging science and technology but I can’t resist including these frog stories (and one dog story). Plus, there may be some tap dancing.

A new (!) fanged frog in Indonesia

This is not the tiny Indonesian fanged frog but it does show you what a fanged frog looks like, from the December 21, 2023 “What Are Fanged Frogs?” posting on the Vajiram and Ravi IAS Study Center website,

Not an Indonesian fanged frog. h/t Vajiram and Ravi IAS Study Center [downloaded from https://vajiramias.com/current-affairs/what-are-fanged-frogs/658416a9f0e178517404afda/]

If you don’t have much time and are interested in the latest fanged frog, check out the December 21, 2023 “What Are Fanged Frogs?” posting as they have relevant information in bullet point form.

On to the specifics about the ‘new’ fanged frog from a December 21, 2023 news item on ScienceDaily,

In general, frogs’ teeth aren’t anything to write home about — they look like pointy little pinpricks lining the upper jaw. But one group of stream-dwelling frogs in Southeast Asia has a strange adaptation: two bony “fangs” jutting out of their lower jawbone. They use these fangs to battle with each other over territory and mates, and sometimes even to hunt tough-shelled prey like giant centipedes and crabs. In a new study, published in the journal PLOS [Public Library of Science] ONE, researchers have described a new species of fanged frog: the smallest one ever discovered.

“This new species is tiny compared to other fanged frogs on the island where it was found, about the size of a quarter,” says Jeff Frederick, a postdoctoral researcher at the Field Museum in Chicago and the study’s lead author, who conducted the research as a doctoral candidate at the University of California, Berkeley.

…

A December 20, 2023 Field Museum news release (also on EurrekAlert), which originated the news item, adds more detail,

“Many frogs in this genus are giant, weighing up to two pounds. At the large end, this new species weighs about the same as a dime.”

In collaboration with the Bogor Zoology Museum, a team from the McGuire Lab at Berkeley   found the frogs on Sulawesi, a rugged, mountainous island that makes up part of Indonesia. “It’s a giant island with a vast network of mountains, volcanoes, lowland rainforest, and cloud forests up in the mountains. The presence of all these different habitats mean that the magnitude of biodiversity across many plants and animals we find there is unreal – rivaling places like the Amazon,” says Frederick.

While trekking through the jungle, members of the joint US-Indonesia amphibian and reptile research team noticed something unexpected on the leaves of tree saplings and moss-covered boulders: nests of frog eggs.

Frogs are amphibians, and they lay eggs that are encapsulated by jelly, rather than a hard, protective shell. To keep their eggs from drying out, most amphibians lay their eggs in water. To the research team’s surprise, they kept spotting the terrestrial egg masses on leaves and mossy boulders several feet above the ground. Shortly after, they began to see the small, brown frogs themselves.

“Normally when we’re looking for frogs, we’re scanning the margins of stream banks or wading through streams to spot them directly in the water,” Frederick says. “After repeatedly monitoring the nests though, the team started to find attending frogs sitting on leaves hugging their little nests.” This close contact with their eggs allows the frog parents to coat the eggs with compounds that keep them moist and free from bacterial and fungal contamination.

Closer examination of the amphibian parents revealed not only that they were tiny members of the fanged frog family, complete with barely-visible fangs, but that the frogs caring for the clutches of eggs were all male. “Male egg guarding behavior isn’t totally unknown across all frogs, but it’s rather uncommon,” says Frederick.

Frederick and his colleagues hypothesize that the frogs’ unusual reproductive behaviors might also relate to their smaller-than-usual fangs. Some of the frogs’ relatives have bigger fangs, which help them ward off competition for spots along the river to lay their eggs in the water. Since these frogs evolved a way to lay their eggs away from the water, they may have lost the need for such big imposing fangs. (The scientific name for the new species is Limnonectes phyllofolia; phyllofolia means “leaf-nester.”)

“It’s fascinating that on every subsequent expedition to Sulawesi, we’re still discovering new and diverse reproductive modes,” says Frederick. “Our findings also underscore the importance of conserving these very special tropical habitats. Most of the animals that live in places like Sulawesi are quite unique, and habitat destruction is an ever-looming conservation issue for preserving the hyper-diversity of species we find there. Learning about animals like these frogs that are found nowhere else on Earth helps make the case for protecting these valuable ecosystems.”

Here’s a link to and a citation for the paper,

A new species of terrestrially-nesting fanged frog (Anura: Dicroglossidae) from Sulawesi Island, Indonesia by Jeffrey H. Frederick, Djoko T. Iskanda, Awal Riyanto, Amir Hamidy, Sean B. Reilly, Alexander L. Stubbs, Luke M. Bloch, Bryan Bach, Jimmy A. McGuire. PLOS ONE 18(12): e0292598 DOI: https://doi.org/10.1371/journal.pone.0292598 Published: December 20, 2023

This paper is open access and online only.

Fatal attraction to … frog noses?

Bob Yirka in a November 28, 2023 article published on phys.org describes research into some unusual mosquito behaviour, Note: Links have been removed,

A pair of environmental and life scientists, one with the University of Newcastle, in Australia, the other the German Center for Integrative Biodiversity Research, has found that one species of mosquito native to Australia targets only the noses of frogs for feeding. In their paper published in the journal Ethology, John Gould and Jose Valdez describe their three-year study of frogs and Mimomyia elegans, a species of mosquito native to Australia

As part of their study of frogs living in a pond on Kooragang Island, the pair took a lot of photographs of the amphibians in their native environment. It was upon returning to their lab and laying out the photographs that they noticed something unique—any mosquito feeding on a frog’s blood was always atop its nose. This spot, they noted, seemed precarious, as mosquitos are part of the frog diet.

A mosquito perches on the nose of a green and yellow frog perched on a branch.
A species of Australian mosquito, Mimomyia elegans, appears to have a predilection for the nostrils of tree frogs, according to new observations published in the journal Ethology. (John Gould) [downloaded from https://www.cbc.ca/radio/asithappens/mosquitoes-on-frog-noses-1.7058168]

Sheena Goodyear posted a December 13, 2023 article containing an embedded Canadian Broadcasting Corporation (CBC) As It Happens radio programme audio file of an interview with researcher John Gould, Note: A link has been removed,

…

So why risk landing on the nose of something that wants to eat you, when there are so many other targets walking around full of delicious blood?

“In all of the occasions that we observed, it seems as if the frog didn’t realize that it had a mosquito on top of it…. They were actually quite happy, just sitting idly, while these mosquitoes were feeding on them,” Gould said.

“So it might be that the area between the eyes is a bit of a blind spot for the frogs.”

It’s also something of a sneak attack by the mosquitoes.

“Some of the mosquitoes first initially landed on the backs of the frogs,” Gould said. “They might avoid being eaten by the frogs by landing away from the head and then walking up to the nostrils to feed.

It’s a plausible theory, says amphibian expert Lea Randall, a Calgary Zoo and Wilder Institute ecologist who wasn’t involved in the research. 

“Frogs have amazing vision, and any mosquito that approached from the front would likely end up as a tasty snack for a frog,” she said.

“Landing on the back and making your way undetected to the nostrils is a good strategy.”

And the reward may just be worth the risk. 

“I could also see the nostrils as being a good place to feed as the skin is very thin and highly vascularized, and thus provides a ready source of blood for a hungry mosquito,” Randall said.

…

Gould admits his friends and loved ones have likely grown weary of hearing him “talking about frogs and nostrils.” But for him, it’s more than a highly specific scientific obsession; it’s about protecting frogs.

His earlier research has suggested that mosquitoes may be a vector for transmitting amphibian chytrid fungus, which is responsible for declines in frog populations worldwide. 

That’s why he had been amassing photos of frogs and mosquitoes in the first place.

“Now that we know where the mosquito is more likely to land, it might give us a better impression about how the infection spreads along the skin of the frog,” he said.

…

But more work needs to be done. His frog nostril research, while it encompasses three years’ of fieldwork, is a natural history observation, not a laboratory study with controlled variables.

“It would be quite interesting to know whether this particular type of mosquito is transferring the chytrid fungus, and also how the fungus spreads once the mosquito has landed,” Gould said.

…

A man in a bright yellow jacket and a light strapped to his forehead poses outside at night with a tiny frog perched on his hand.
Gould describes himself as a ‘vampire scientist’ who stays up all night studying nocturnal tree frogs in Australia. ‘They’re so soft and timid a lot of the times,’ he said. ‘They’re quite a special little, little animal.’ (Submitted by John Gould)

Vampire scientist, eh? You can find the embedded 6 mins. 28 secs. audio file in the December 13, 2023 article on the CBC website.

Here’s a link to and a citation for the research paper,

A little on the nose: A mosquito targets the nostrils of tree frogs for a blood meal by John Gould, Jose W. Valdez. Ethology DOI: https://doi.org/10.1111/eth.13424 First published: 21 November 2023

This paper is open access.

Gifted dogs

Caption: Shira, 6 -year-old, female, Border Collie mix, that was rescued at a young age. She lives in New Jersey, and knows the names of 125 toys. Credit Photo: Tres Hanley-Millman

A December 14, 2023 news item on phys.org describes some intriguing research from Hungary,

All dog owners think that their pups are special. Science now has documented that some rare dogs are even more special. They have a talent for learning hundreds of names of dog toys. Due to the extreme rarity of this phenomenon, until recently, very little was known about these dogs, as most of the studies that documented this ability included only a small sample of one or two dogs.

A December 18,2023 Eötvös Loránd University (ELTE) press release (also on EurekAlert but published December 14, 2023), which originated the news item, delves further into the research,

In a previous study, the scientists found that only very few dogs could learn the names of object, mostly dog toys. The researchers wanted to understand this phenomenon better and, so they needed to find more dogs with this ability. But finding dogs with this rare talent was a challenge! For five years, the researchers tirelessly searched across the world for these unique Gifted Word Learner (GWL) dogs. As part of this search, in 2020, they launched a social media campaign and broadcasted their experiments with GWL dogs, in the hope of finding more GWL dogs.

“This was a citizen science project” explains Dr. Claudia Fugazza, team leader. “When a dog owner told us they thought their dog knew toy names, we gave them instructions on how to self-test their dog and asked them to send us the video of the test”. The researchers then held an online meeting with the owners to test the dog’s vocabulary under controlled conditions and, if the dog showed he knew the names of his toys, the researchers asked the owners to fill out a questionnaire. “In the questionnaire, we asked the owners about their dog’s life experience, their own experience in raising and training dogs, and about the process by which the dog came to learn the names of his/her toys” explains Dr. Andrea Sommese, co-author.

VIDEO ABSTRACT ABOUT THE RESEARCH

The researchers found 41 dogs from 9 different countries: the US, the UK, Brazil, Canada, Norway, Netherlands, Spain, Portugal and Hungary. Most of the previous studies on this topic included Border collies. So, while object label learning is very rare even in Border collies, it was not surprising that many of the dogs participating in the current study (56%) belonged to this breed. However, the study documented the ability to learn toy names in a few dogs from non-working breeds, such as two Pomeranians, one Pekingese, one Shih Tzu, a Corgi, a Poodle, and a few mixed breeds.

“Surprisingly, most owners reported that they did not intentionally teach their dogs toy names, but rather that the dogs just seemed to spontaneously pick up the toy names during unstructured play sessions,” says Shany Dror, lead researcher. In addition, the vast majority of owners participating in the study had no professional background in dog training and the researchers found no correlations between the owners’ level of experience in handling and training dogs, and the dogs’ ability to select the correct toys when hearing its names.

“In our previous studies we have shown that GWL dogs learn new object names very fast” explains Dror. “So, it is not surprising that when we conducted the test with the dogs, the average number of toys known by the dogs was 29, but when we published the results, more than 50% of the owners reported that their dogs had already acquired a vocabulary of over 100 toy names”.

“Because GWL dogs are so rare, until now there were only anecdotes about their background” explains Prof. Adam Miklósi, Head of the Ethology Department at ELTE and co-author. “The rare ability to learn object names is the first documented case of talent in a non-human species. The relatively large sample of dogs documented in this study, helps us to identify the common characteristics that are shared among these dogs, and brings us one step closer in the quest of understanding their unique ability”.

This research is part of the Genius Dog Challenge research project which aims to understand the unique talent that Gifted Word Learner dogs have. The researchers encourage dog owners who believe their dogs know multiple toy names, to contact them via the Genius Dog Challenge website.

Here’s a link to and a citation for the research paper,

A citizen science model turns anecdotes into evidence by revealing similar characteristics among Gifted Word Learner dogs by Shany Dror, Ádám Miklósi, Andrea Sommese & Claudia Fugazza. Scientific Reports volume 13, Article number: 21747 (2023) DOI: https://doi.org/10.1038/s41598-023-47864-5 Published: 14 December 2023

This paper is open access.

The End with an origin story NORAD’s Santa Tracker and some tap dancing

At the height of Cold War tensions between the US and Russia, the red phone (to be used only by the US president or a four star genera) rang at the North American Aerospace Defense Command (NORAD). Before the conversation ended, the colonel in charge had driven a child to tears and put in motion the start of a beloved Christmas tradition.

There’s a short version and a long version and if you want all the details read both,

As for the tap dancing, I have three links:

  1. “Irish Dancers Face Off Against American Tap Dancers To Deliver EPIC Performance!” is an embedded 8 mins. dance off video (scroll down past a few paragraphs) in Erin Perri’s September 1, 2017 posting for themix.net. And, if you scroll further down to the bottom of Perri’s post, you’ll see an embedded video of Sammy Davis Jr.

…

In the video …, along with his dad and uncle, Sammy performs at an unbelievable pace. In the last 30 seconds of this routine, Sammy demonstrates more talent than other dancers are able to cram into a lifelong career! You can see these three were breakdancing long before it became a thing in the 1980s and they did it wearing tap shoes!

..

2. “Legendary Nicholas Brothers Dance Routine Was Unrehearsed and Filmed in One Take” embedded at the end of Emma Taggart’s October 4, 2019 posting on mymodernmet.com

3. Finally, there’s “Jill Biden releases extravagant dance video to celebrate Christmas at the White House” with a video file embedded (wait for it to finish loading and scroll down a few paragraphs) in Kate Fowler’s December 15, (?) 2023 article for MSN. It’s a little jazz, a little tap, and a little Christmas joy.

Joyeux Noël!

Dealing with mosquitos: a robot story and an engineered human tissue story

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I have two ‘mosquito and disease’ stories, the first concerning dengue fever and the second, malaria.

Dengue fever in Taiwan

A June 8, 2023 news item on phys.org features robotic vehicles, dengue fever, and mosquitoes,

Unmanned ground vehicles can be used to identify and eliminate the breeding sources of mosquitos that carry dengue fever in urban areas, according to a new study published in PLOS Neglected Tropical Diseases by Wei-Liang Liu of the Taiwan National Mosquito-Borne Diseases Control Research Center, and colleagues.

It turns out sewers are a problem according to this June 8, 2023 PLOS (Public Library of Science) news release on EurekAlert, provides more context and detail,

Dengue fever is an infectious disease caused by the dengue virus and spread by several mosquito species in the genus Aedes, which also spread chikungunya, yellow fever and zika. Through the process of urbanization, sewers have become easy breeding grounds for Aedes mosquitos and most current mosquito monitoring programs struggle to monitor and analyze the density of mosquitos in these hidden areas.

In the new control effort, researchers combined a crawling robot, wire-controlled cable car and real-time monitoring system into an unmanned ground vehicle system (UGV) that can take high-resolution, real-time images of areas within sewers. From May to August 2018, the system was deployed in five administrative districts in Kaohsiung city, Taiwan, with covered roadside sewer ditches suspected to be hotspots for mosquitos. Mosquito gravitraps were places above the sewers to monitor effects of the UGV intervention on adult mosquitos in the area.

In 20.7% of inspected sewers, the system found traces of Aedes mosquitos in stages from larvae to adult. In positive sewers, additional prevention control measures were carried out, using either insecticides or high-temperature water jets.  Immediately after these interventions, the gravitrap index (GI)—  a measure of the adult mosquito density nearby— dropped significantly from 0.62 to 0.19.

“The widespread use of UGVs can potentially eliminate some of the breeding sources of vector mosquitoes, thereby reducing the annual prevalence of dengue fever in Kaohsiung city,” the authors say.

Here’s a link to and a citation for the paper,

Use of unmanned ground vehicle systems in urbanized zones: A study of vector Mosquito surveillance in Kaohsiung by Yu-Xuan Chen, Chao-Ying Pan, Bo-Yu Chen, Shu-Wen Jeng, Chun-Hong Chen, Joh-Jong Huang, Chaur-Dong Chen, Wei-Liang Liu. PLOS Neglected Tropical Diseases DOI: https://doi.org/10.1371/journal.pntd.0011346 Published: June 8, 2023

This paper is open access.

Dengue on the rise

Like many diseases, dengue is one where you may not have symptoms (asymptomatic), or they’re relatively mild and can be handled at home, or you may need care in a hospital and, in some cases, it can be fatal.

The World Health Organization (WHO) notes that dengue fever cases have increased exponentially since 2000 (from the March 17, 2023 version of the WHO’s “Dengue and severe dengue” fact sheet),

Global burden

The incidence of dengue has grown dramatically around the world in recent decades, with cases reported to WHO increased from 505 430 cases in 2000 to 5.2 million in 2019. A vast majority of cases are asymptomatic or mild and self-managed, and hence the actual numbers of dengue cases are under-reported. Many cases are also misdiagnosed as other febrile illnesses (1).

One modelling estimate indicates 390 million dengue virus infections per year of which 96 million manifest clinically (2). Another study on the prevalence of dengue estimates that 3.9 billion people are at risk of infection with dengue viruses.

The disease is now endemic in more than 100 countries in the WHO Regions of Africa, the Americas, the Eastern Mediterranean, South-East Asia and the Western Pacific. The Americas, South-East Asia and Western Pacific regions are the most seriously affected, with Asia representing around 70% of the global disease burden.

Dengue is spreading to new areas including Europe, [emphasis mine] and explosive outbreaks are occurring. Local transmission was reported for the first time in France and Croatia in 2010 [emphasis mine] and imported cases were detected in 3 other European countries.

The largest number of dengue cases ever reported globally was in 2019. All regions were affected, and dengue transmission was recorded in Afghanistan for the first time. The American Region reported 3.1 million cases, with more than 25 000 classified as severe. A high number of cases were reported in Bangladesh (101 000), Malaysia (131 000) Philippines (420 000), Vietnam (320 000) in Asia.

Dengue continues to affect Brazil, Colombia, the Cook Islands, Fiji, India, Kenya, Paraguay, Peru, the Philippines, the Reunion Islands and Vietnam as of 2021. 

There’s information from an earlier version of the fact sheet, in my July 2, 2013 posting, highlighting different aspects of the disease, e.g., “About 2.5% of those affected die.”

A July 21, 2023 United Nations press release warns that the danger from mosquitoes spreading dengue fever could increase along with the temperature,

Global warming marked by higher average temperatures, precipitation and longer periods of drought, could prompt a record number of dengue infections worldwide, the World Health Organization (WHO) warned on Friday [July 21, 2023].

Despite the absence of mosquitoes infected with the dengue virus in Canada, the government has a Dengue fever information page. At this point, the concern is likely focused on travelers who’ve contracted the disease from elsewhere. However, I am guessing that researchers are keeping a close eye on Canadian mosquitoes as these situations can change.

Malaria in Florida (US)

The researchers from the University of Central Florida (UCF) couldn’t have known when they began their project to study mosquito bites and disease that Florida would register its first malaria cases in 20 years this summer, from a July 26, 2023 article by Stephanie Colombini for NPR ([US] National Public Radio), Note: Links have been removed,

…

First local transmission in U.S. in 20 years

Heath [Hannah Heath] is one of eight known people in recent months who have contracted malaria in the U.S., after being bitten by a local mosquito, rather than while traveling abroad. The cases comprise the nation’s first locally transmitted outbreak in 20 years. The last time this occurred was in 2003, when eight people tested positive for malaria in Palm Beach, Fla.

One of the eight cases is in Texas; the rest occurred in the northern part of Sarasota County.

The Florida Department of Health recorded the most recent case in its weekly arbovirus report for July 9-15 [2023].

For the past month, health officials have issued a mosquito-borne illness alert for residents in Sarasota and neighboring Manatee County. Mosquito management teams are working to suppress the population of the type of mosquito that carries malaria, Anopheles.

Sarasota Memorial Hospital has treated five of the county’s seven malaria patients, according to Dr. Manuel Gordillo, director of infection control.

“The cases that are coming in are classic malaria, you know they come in with fever, body aches, headaches, nausea, vomiting, diarrhea,” Gordillo said, explaining that his hospital usually treats just one or two patients a year who acquire malaria while traveling abroad in Central or South America, or Africa.

…

All the locally acquired cases were of Plasmodium vivax malaria, a strain that typically produces milder symptoms or can even be asymptomatic, according to the Centers for Disease Control and Prevention. But the strain can still cause death, and pregnant people and children are particularly vulnerable.

…

Malaria does not spread from human-to-human contact; a mosquito carrying the disease has to bite someone to transmit the parasites.

Workers with Sarasota County Mosquito Management Services have been especially busy since May 26 [2023], when the first local case was confirmed.

Like similar departments across Florida, the team is experienced in responding to small outbreaks of mosquito-borne illnesses such as West Nile virus or dengue. They have protocols for addressing travel-related cases of malaria as well, but have ramped up their efforts now that they have confirmation that transmission is occurring locally between mosquitoes and humans.

…

While organizations like the World Health Organization have cautioned climate change could lead to more global cases and deaths from malaria and other mosquito-borne diseases, experts say it’s too soon to tell if the local transmission seen these past two months has any connection to extreme heat or flooding.

“We don’t have any reason to think that climate change has contributed to these particular cases,” said Ben Beard, deputy director of the CDC’s US Centers for Disease Control and Prevention] division of vector-borne diseases and deputy incident manager for this year’s local malaria response.

“In a more general sense though, milder winters, earlier springs, warmer, longer summers – all of those things sort of translate into mosquitoes coming out earlier, getting their replication cycles sooner, going through those cycles faster and being out longer,” he said. And so we are concerned about the impact of climate change and environmental change in general on what we call vector-borne diseases.”.

Beard co-authored a 2019 report that highlights a significant increase in diseases spread by ticks and mosquitoes in recent decades. Lyme disease and West Nile virus were among the top five most prevalent.

“In the big picture it’s a very significant concern that we have,” he said.

…

Engineered tissue and bloodthirsty mosquitoes

A June 8, 2023 University of Central Florida (UCF) news release (also on EurekAlert) by Eric Eraso describes the research into engineered human tissue and features a ‘bloodthirsty’ video. First, the video,

Note: A link has been removed,

A UCF research team has engineered tissue with human cells that mosquitoes love to bite and feed upon — with the goal of helping fight deadly diseases transmitted by the biting insects.

A multidisciplinary team led by College of Medicine biomedical researcher Bradley Jay Willenberg with Mollie Jewett (UCF Burnett School of Biomedical Sciences) and Andrew Dickerson (University of Tennessee) lined 3D capillary gel biomaterials with human cells to create engineered tissue and then infused it with blood. Testing showed mosquitoes readily bite and blood feed on the constructs. Scientists hope to use this new platform to study how pathogens that mosquitoes carry impact and infect human cells and tissues. Presently, researchers rely largely upon animal models and cells cultured on flat dishes for such investigations.

Further, the new system holds great promise for blood feeding mosquito species that have proven difficult to rear and maintain as colonies in the laboratory, an important practical application. The Willenberg team’s work was published Friday in the journal Insects.

Mosquitos have often been called the world’s deadliest animal, as vector-borne illnesses, including those from mosquitos cause more than 700,000 deaths worldwide each year. Malaria, dengue, Zika virus and West Nile virus are all transmitted by mosquitos. Even for those who survive these illnesses, many are left suffering from organ failure, seizures and serious neurological impacts.

“Many people get sick with mosquito-borne illnesses every year, including in the United States. The toll of such diseases can be especially devastating for many countries around the world,” Willenberg says.

This worldwide impact of mosquito-borne disease is what drives Willenberg, whose lab employs a unique blend of biomedical engineering, biomaterials, tissue engineering, nanotechnology and vector biology to develop innovative mosquito surveillance, control and research tools. He said he hopes to adapt his new platform for application to other vectors such as ticks, which spread Lyme disease.

“We have demonstrated the initial proof-of-concept with this prototype” he says. “I think there are many potential ways to use this technology.”

Captured on video, Willenberg observed mosquitoes enthusiastically blood feeding from the engineered tissue, much as they would from a human host. This demonstration represents the achievement of a critical milestone for the technology: ensuring the tissue constructs were appetizing to the mosquitoes.

“As one of my mentors shared with me long ago, the goal of physicians and biomedical researchers is to help reduce human suffering,” he says. “So, if we can provide something that helps us learn about mosquitoes, intervene with diseases and, in some way, keep mosquitoes away from people, I think that is a positive.”

Willenberg came up with the engineered tissue idea when he learned the National Institutes of Health (NIH) was looking for new in vitro 3D models that could help study pathogens that mosquitoes and other biting arthropods carry.

“When I read about the NIH seeking these models, it got me thinking that maybe there is a way to get the mosquitoes to bite and blood feed [on the 3D models] directly,” he says. “Then I can bring in the mosquito to do the natural delivery and create a complete vector-host-pathogen interface model to study it all together.”

As this platform is still in its early stages, Willenberg wants to incorporate addition types of cells to move the system closer to human skin. He is also developing collaborations with experts that study pathogens and work with infected vectors, and is working with mosquito control organizations to see how they can use the technology.

“I have a particular vision for this platform, and am going after it. My experience too is that other good ideas and research directions will flourish when it gets into the hands of others,” he says. “At the end of the day, the collective ideas and efforts of the various research communities propel a system like ours to its full potential. So, if we can provide them tools to enable their work, while also moving ours forward at the same time, that is really exciting.”

Willenberg received his Ph.D. in biomedical engineering from the University of Florida and continued there for his postdoctoral training and then in scientist, adjunct scientist and lecturer positions. He joined the UCF College of Medicine in 2014, where he is currently an assistant professor of medicine.

Willenberg is also a co-founder, co-owner and manager of Saisijin Biotech, LLC and has a minor ownership stake in Sustained Release Technologies, Inc. Neither entity was involved in any way with the work presented in this story. Team members may also be listed as inventors on patent/patent applications that could result in royalty payments. This technology is available for licensing. To learn more, please visit ucf.flintbox.com/technologies/44c06966-2748-4c14-87d7-fc40cbb4f2c6.

Here’s a link to and a citation for the paper,

Engineered Human Tissue as A New Platform for Mosquito Bite-Site Biology Investigations by Corey E. Seavey, Mona Doshi, Andrew P. Panarello, Michael A. Felice, Andrew K. Dickerson, Mollie W. Jewett and Bradley J. Willenberg. Insects 2023, 14(6), 514; https://doi.org/10.3390/insects14060514 Published: 2 June 2023

This paper is open access.

That final paragraph in the news release is new to me. I’ve seen them list companies where the researchers have financial interests but this is the first time I’ve seen a news release that offers a statement attempting to cover all the bases including some future possibilities such as: “Team members may also be listed as inventors on patent/patent applications that could result in royalty payments.“

It seems pretty clear that there’s increasing concern about mosquito-borne diseases no matter where you live.

Controlling agricultural pests with CRISPR-based technology

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CRISPR (clustered regularly interspaced short palindromic repeats) technology is often touted as being ‘precise’, which as far as I can tell, is not exactly the case (see my Nov. 28, 2018 posting about the CRISPR babies [scroll down about 30% of the way for the first hint that CRISPR isn’t]). So, it’s a bit odd to see the word ‘precise’ used as part of a new CRISPR-based technology’s name (from a January 8, 2019 news item on ScienceDaily,

Using the CRISPR gene editing tool, Nikolay Kandul, Omar Akbari and their colleagues at UC San Diego [UC is University of California] and UC Berkeley devised a method of altering key genes that control insect sex determination and fertility.

A description of the new “precision-guided sterile insect technique,” [emphasis mine] or pgSIT, is published Jan. 8 [2019] in the journal Nature Communications.

A January 8, 209 UCSD press release (also on EurekAlert) by Mario Aguilera, which originated the news item, delves further into the research,

When pgSIT-derived eggs are introduced into targeted populations, the researchers report, only adult sterile males emerge, resulting in a novel, environmentally friendly and relatively low-cost method of controlling pest populations in the future.

“CRISPR technology has empowered our team to innovate a new, effective, species-specific, self-limiting, safe and scalable genetic population control technology with remarkable potential to be developed and utilized in a plethora of insect pests and disease vectors,” said Akbari, an assistant professor in UC San Diego’s Division of Biological Sciences. “In the future, we strongly believe this technology will be safely used in the field to suppress and even eradicate target species locally, thereby revolutionizing how insects are managed and controlled going forward.”

Since the 1930s, agricultural researchers have used select methods to release sterile male insects into the wild to control and eradicate pest populations. In the 1950s, a method using irradiated males was implemented in the United States to eliminate the pest species known as the New World Screwworm fly, which consumes animal flesh and causes extensive damage to livestock. Such radiation-based methods were later used in Mexico and parts of Central America and continue today.

Instead of radiation, the new pgSIT (precision-guided sterile insect technique), developed over the past year-and-a-half by Kandul and Akbari in the fruit fly Drosophila, uses CRISPR to simultaneously disrupt key genes that control female viability and male fertility in pest species. pgSIT, the researchers say, results in sterile male progeny with 100 percent efficiency. Because the targeted genes are common to a vast cross-section of insects, the researchers are confident the technology can be applied to a range of insects, including disease-spreading mosquitoes.

The researchers envision a system in which scientists genetically alter and produce eggs of a targeted pest species. The eggs are then shipped to a pest location virtually anywhere in the world, circumventing the need for a production facility on-site. Once the eggs are deployed at the pest location, the researchers say, the newly born sterile males will mate with females in the wild and be incapable of producing offspring, driving down the population.

“This is a novel twist of a very old technology,” said Kandul, an assistant project scientist in UC San Diego’s Division of Biological Sciences. “That novel twist makes it extremely portable from one species to another species to suppress populations of mosquitoes or agricultural pests, for example those that feed on valuable wine grapes.”

The new technology is distinct from continuously self-propagating “gene drive” systems that propagate genetic alterations from generation to generation. Instead, pgSIT is considered a “dead end” since male sterility effectively closes the door on future generations.

“The sterile insect technique is an environmentally safe and proven technology,” [emphasis mine] the researchers note in the paper. “We aimed to develop a novel, safe, controllable, non-invasive genetic CRISPR-based technology that could be transferred across species and implemented worldwide in the short-term to combat wild populations.”

With pgSIT proven in fruit flies, the scientists are hoping to develop the technology in Aedes aegypti, the mosquito species responsible for transmitting dengue fever, Zika, yellow fever and other diseases to millions of people.

“The extension of this work to other insect pests could prove to be a general and very useful strategy to deal with many vector-borne diseases that plague humanity and wreak havoc an agriculture globally,” said Suresh Subramani, global director of the Tata Institute for Genetics and Society.

I have one comment about the ‘safety’ of the sterile insect technique. It’s been safe up until now but, assuming this technique works as described: What happens as this new and more powerful technique is more widely deployed possibly eliminating whole species of insects? Might these ‘pests’ have a heretofore unknown beneficial effect somewhere in the food chain or in an ecosystem? Or, there may be other unintended consequences.

Moving on, here’s a link to and a citation for the paper,

Transforming insect population control with precision guided sterile males with demonstration in flies by Nikolay P. Kandul, Junru Liu, Hector M. Sanchez C., Sean L. Wu, John M. Marshall, & Omar S. Akbari. Nature Communications volume 10, Article number: 84 (2019) DOI: https://doi.org/10.1038/s41467-018-07964-7 Published 08 January 2019

This paper is open access.

The researchers have made this illustrative image available,

Caption: This is a schematic of the new precision-guided sterile insect technique (pgSIT), which uses components of the CRISPR/Cas9 system to disrupt key genes that control female viability and male fertility, resulting in sterile male progeny. Credit: Nikolay Kandul, Akbari Lab, UC San Diego

Weirdly fascinating account of malaria-carrying mosquitoes and insecticide-treated bed nets

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Researchers at the Liverpool School of Tropical Medicine (LSTM) have tracked mosquitoes to observe how they interact with insecticide-laden nets. From a Sept. 1, 2015 LSTM press release (also on EurekAlert),

LSTM vector biologists Dr Philip McCall and Ms Josie Parker worked with optical engineers Prof David Towers, Dr Natalia Angarita and Dr Catherine Towers from the University of Warwick’s School of Engineering to develop infrared video tracking technology that follows individual mosquitoes in flight as they try to reach a human sleeper inside a bed net. This system allowed the scientists to measure, define and characterise in fine detail, the behavioural events and sequences of the main African malaria vector, Anopheles gambiae, as it interacts with the net. Funded as part of the €12M AvecNet research consortium, the team’s initial results are published today in the journal Nature Scientific Reports.

Dr Philip McCall, senior author on the paper, said: “Essentially, the results demonstrated that an LLIN [Long-lasting insecticidal bed net] functions as a highly efficient, fast-acting, human-baited insecticidal trap. LLINs do not repel mosquitoes – they deliver insecticide very rapidly after the briefest contact: LLIN contact of less than 1 minute per mosquito during the first ten minutes can reduce mosquito activity such that after thirty minutes, virtually no mosquitoes are still flying. Surprisingly, mosquitoes were able to detect nets of any kind while still in flight, allowing them to decelerate before they ‘collided’ with the net surface.”

The use of this innovative approach to mosquito behaviour has provided unprecedented insight into the mode of action of our most important tool for preventing malaria transmission, under conditions that are as close to natural as possible. The findings potentially could influence many aspects of mosquito control, ranging from how we test mosquito populations for insecticide resistance to the design of a next generation of LLINs. An MRC Confidence in Concept grant has funded the team to use the tracking system to explore a number of novel LLIN designs, already patented as an outcome from the current research.

The tracking system also has been deployed in a rural Tanzania, results of which will be reported shortly. The team recently was awarded £0.9M support from the Medical Research Council (MRC) for the next stage of this project, where they will use a larger three-dimensional system to track mosquitoes throughout the entire domestic environment, in experimental houses in Tanzania.

Dr McCall continued: “preliminary results in field tests indicate that these laboratory findings are consistent with behaviour of wild mosquito populations which is very encouraging. We are at the early stages of this research, but we hope that our findings, and the use of this cutting edge technology, can contribute to the development of new and advanced vector control tools that will continue to save lives in endemic countries throughout the world.”

The fascinating part follows the link to and citation for the paper,

Infrared video tracking of Anopheles gambiae at insecticide-treated bed nets reveals rapid decisive impact after brief localised net contact by Josephine E.A. Parker, Natalia Angarita-Jaimes, Mayumi Abe, Catherine E. Towers, David Towers, & Philip J. McCall. Scientific Reports 5, Article number: 13392 (2015) doi:10.1038/srep13392 Published online: 01 September 2015

This open access paper provides an explanation for why this work was undertaken,

Delivering the ‘next generation’ of LLINs or similar tools will require a thorough understanding of how LLINs function, yet remarkably little is known of the mode of action or of precisely how mosquitoes behave at the LLIN interface. Recent studies using ‘sticky-nets’ reported that host-seeking female Anopheles spp. landed preferentially on the top surface of bed nets7,8 but that lethal capture method recorded only a single landing event and no other behaviours before or after. Although clustering at the net roof is likely to be a response to an attractant ‘plume’ rising from the human beneath [emphasis mine], this too remains speculative because knowledge of mosquito flight behaviour prior to blood-feeding and of the identity and location of the key attractants that mediate the host-seeking response is limited9,10,11,12. Importantly, how insecticide treatments influence that response is unclear. Some studies reported that insecticide residues repelled mosquitoes prior to contact13,14, which would reduce or eliminate the chance of mosquitoes receiving an effective dose and potentially divert them to unprotected hosts15. Others found no evidence for such repellency16,17,18,19 indicating that LLINs attract and impact on mosquitoes by direct contact.

A further complication is the existence of what is termed ‘contact-irritancy’ or ‘excito-repellency’ [emphasis miine], whereby brief exposure to an insecticide can result in mosquitoes exhibiting avoidance behaviour, potentially before a lethal dose has been delivered13,20. Remarkably, some basic details are missing: e.g. the minimum duration of LLIN contact necessary to deliver an effective dosage is not known. Despite these phenomena being recognised for decades20,21,22, when and how they occur and their relative importance in selecting for insecticide resistance have never been fully elucidated.

Consequently, behavioural resistance [emphasis mine] to insecticides remains poorly understood and rarely reported in mosquitoes, though the risk of vector populations switching blood-feeding times, locations or host preferences in order to avoid LLINs is recognized and closely monitored today23,24,25. However, additional but less apparent or detectable behavioural changes also might exist, potentially conferring partial or complete insecticide resistance (e.g. changes in sensitivity to repellents, attractants, or modified flight or resting behaviours). In the absence of definitions or quantifications of the basic behavioural events likely to be affected26,27, these changes cannot be investigated, let alone monitored.

I am fascinated by the ‘attractant plume’, ‘excito-repellency’, and the (new to me) notion that mosquitoes can exhibit behavioural resistance.

Hong Kong, MosquitNo, and Dengue fever

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The most substantive piece I’ve written on dengue fever and a nanotechnology-enabled approach to the problem was a 2013 post explaining why the fever is of such concern, which also included information about a proposed therapeutic intervention by Nanoviricides. From the July 2, 2013 posting, here’s more about the magnitude of the problem,

… the WHO (World Health Organization) fact sheet no. 117,

The incidence of dengue has grown dramatically around the world in recent decades. Over 2.5 billion people – over 40% of the world’s population – are now at risk from dengue. WHO currently estimates there may be 50–100 million dengue infections worldwide every year.

Before 1970, only nine countries had experienced severe dengue epidemics. The disease is now endemic in more than 100 countries in Africa, the Americas, the Eastern Mediterranean, South-east Asia and the Western Pacific. The American, South-east Asia and the Western Pacific regions are the most seriously affected.

Cases across the Americas, South-east Asia and Western Pacific have exceeded 1.2 million cases in 2008 and over 2.3 million in 2010 (based on official data submitted by Member States). Recently the number of reported cases has continued to increase. In 2010, 1.6 million cases of dengue were reported in the Americas alone, of which 49 000 cases were severe dengue.

Not only is the number of cases increasing as the disease spreads to new areas, but explosive outbreaks are occurring. The threat of a possible outbreak of dengue fever now exists in Europe and local transmission of dengue was reported for the first time in France and Croatia in 2010 and imported cases were detected in three other European countries. A recent (2012) outbreak of dengue on Madeira islands of Portugal has resulted in over 1800 cases and imported cases were detected in five other countries in Europe apart from mainland Portugal.

An estimated 500 000 people with severe dengue require hospitalization each year, a large proportion of whom are children. About 2.5% of those affected die.

Fast forwarding to 2015, this latest information about dengue fever features a preventative approach being taken in Hong Kong according to a July 5, 2015 article by Timmy Sung  for the South China Morning Post,

Dutch insect repellent innovator Mosquitno targets Hong Kong as dengue fever cases rise

A Dutch company says it has invented an insect repellent using nanotechnology which can keep clothes and homes mosquito-free for up to three months.

Mosquitno has been invited by a government body to begin trading in Hong Kong as the number of cases reported in the city of the deadly mosquito-borne dengue fever rises.

The new repellent does not include the active ingredient used in many insect repellents, DEET, which has question marks surrounding its safety.

Figures from the Department of Health show the number of dengue fever cases reported rose 8 per cent last year, to 112. There were 34 cases in the first five months of this year, 36 per cent more than in the same period last year. Mosquitoes are most active in the summer months.

MosquitNo does use an ingredient, IR3535, which has caused concern (from Sung’s article),

The Consumer Council has previously warned that IR3535-based mosquito repellents can break down plastic materials and certain synthetic fibres, but Wijnen [Erwin Wijnen, director of the {Mosqutino’s} brand development and global travel retailing] said the ingredient combined with nanotechnology is safe and there was no possibility it would damage clothes.

I was not able to find out more about the company’s nanotechnology solution as applied to MosquitNo,

The NANO Series is a revolutionary, innovative technology designed by scientists especially for MosquitNo. This line utilizes this-breaking insect repellent technology in various products including wipes, textile spray, fabric softener and bracelets. This technology and our trendy applications are truly industry-changing and MosquitNo is at the leading edge!

The active component in all our awesome products within this range is IR3535.

That’s it for technical detail. At least, for now.

Killing mosquitos and other pests with genetics-based technology

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Having supplied more than one tasty meal for mosquitos (or, as some prefer, mosquitoes), I am not their friend but couldn’t help but wonder about unintended consequences (as per Max Weber) on reading about a new patent awarded to Kansas State University (from a Nov. 12, 2014 news item on Nanowerk),

Kansas State University researchers have developed a patented method of keeping mosquitoes and other insect pests at bay.

U.S. Patent 8,841,272, “Double-Stranded RNA-Based Nanoparticles for Insect Gene Silencing,” was recently awarded to the Kansas State University Research Foundation, a nonprofit corporation responsible for managing technology transfer activities at the university. The patent covers microscopic, genetics-based technology that can help safely kill mosquitos and other insect pests.

A Nov. 12, 2014 Kansas State University news release, which originated the news item, provides more detail about the research,

Kun Yan Zhu, professor of entomology; Xin Zhang, research associate in the Division of Biology; and Jianzhen Zhang, visiting scientist from Shanxi University in China, developed the technology: nanoparticles comprised of a nontoxic, biodegradable polymer matrix and insect derived double-stranded ribonucleic acid, or dsRNA. Double-stranded RNA is a synthesized molecule that can trigger a biological process known as RNA interference, or RNAi, to destroy the genetic code of an insect in a specific DNA sequence.

The technology is expected to have great potential for safe and effective control of insect pests, Zhu said.

“For example, we can buy cockroach bait that contains a toxic substance to kill cockroaches. However, the bait could potentially harm whatever else ingests it,” Zhu said. “If we can incorporate dsRNA specifically targeting a cockroach gene in the bait rather than a toxic substance, the bait would not harm other organisms, such as pets, because the dsRNA is designed to specifically disable the function of the cockroach gene.”

Researchers developed the technology while looking at how to disable gene functions in mosquito larvae. After testing a series of unsuccessful genetic techniques, the team turned to a nanoparticle-based approach.

Once ingested, the nanoparticles act as a Trojan horse, releasing the loosely bound dsRNA into the insect gut. The dsRNA then triggers a genetic chain reaction that destroys specific messenger RNA, or mRNA, in the developing insects. Messenger RNA carries important genetic information.

In the studies on mosquito larvae, researchers designed dsRNA to target the mRNA encoding the enzymes that help mosquitoes produce chitin, the main component in the hard exoskeleton of insects, crustaceans and arachnids.

Researchers found that the developing mosquitoes produced less chitin. As a result, the mosquitoes were more prone to insecticides as they no longer had a sufficient amount of chitin for a normal functioning protective shell. If the production of chitin can be further reduced, the insects can be killed without using any toxic insecticides.

While mosquitos were the primary insect for which the nanoparticle-based method was developed, the technology can be applied to other insect pests, Zhu said.

“Our dsRNA molecules were designed based on specific gene sequences of the mosquito,” Zhu said. “You can design species-specific dsRNA for the same or different genes for other insect pests. When you make baits containing gene-specific nanoparticles, you may be able to kill the insects through the RNAi pathway. We see this having really broad applications for insect pest management.”

The patent is currently available to license through the Kansas State University Institute for Commercialization, which licenses the university’s intellectual property. The Institute for Commercialization can be contacted at 785-532-3900 and ic@k-state.edu.

Eight U.S. patents have been awarded to the Kansas State University Research Foundation in 2014 for inventions by Kansas State University researchers.

Here’s an image of the ‘Trojan horse’ nanoparticles,

The nanoparticles, pictured as gold colored, are less than 100 nanometers in diameter. photo credit: bogdog Dan via photopincc

The nanoparticles, pictured as gold colored, are less than 100 nanometers in diameter. photo credit: bogdog Dan via photopincc

My guess is that the photographer has added some colour such as the gold and the pink to enhance the image as otherwise this would be a symphony of grey tones.

So, if this material will lead to weakened chitin such that pesticides and insecticides are more effective, does this mean that something else in the food chain will suffer because it no longer has mosquitos and other pests to munch on?

One last note, usually my ‘mosquito’ pieces concern malaria and the most recent of those was a Sept. 4, 2014 posting about a possible malaria vaccine being developed at the University of Connecticut.

Dragonfly and locust rubber

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There’s a protein in some insects such as dragonflies, mosquitoes (!) and locusts which is superior to synthetic rubber according to a July 30, 2013 news release from the American Chemical Society (ACS) [also on EurekAlert],

Kristi Kiick and colleagues explain that scientists discovered resilin a half-century ago in the wing hinges of locusts and elastic tendons of dragonflies. The extraordinary natural protein tops the best synthetic rubbers. Resilin can stretch to three times its original length, for instance, and then spring back to its initial shape without losing its elasticity, despite repeated stretching and relaxing cycles. That’s a crucial trait for insects that must flap or jump millions of times over their lifetimes. Scientists first synthesized resilin in 2005 and have been striving to harness its properties in medicine.

Kiick’s team describes how their own research and experiments by other scientists are making major strides toward practical applications of resilin. Scientists have modified resilin with gold nanoparticles for possible use in diagnostics, engineered mosquito-based resin to act like human cartilage and developed a hybrid material for cardiovascular applications. “This increasing amount of knowledge gained from studies on natural resilin and resilin-like polypeptides continues to inspire new designs and applications of recombinant resilin-based biopolymers in biomedical and biotechnological applications,” the scientists state.

Illustrating 'insect rubber' [downloaded from http://pubs.acs.org/doi/full/10.1021/mz4002194]

Illustrating ‘insect rubber’ [downloaded from http://pubs.acs.org/doi/full/10.1021/mz4002194]

Here’s a link to and a citation for the researchers’ biomimicry paper published by ACS Macro Letters,

Resilin-Based Materials for Biomedical Applications by Linqing Li and Kristi L. Kiick. ACS Macro Lett., 2013, 2, pp 635–640 DOI: 10.1021/mz4002194 Publication Date (Web): July 11, 2013
Copyright © 2013 American Chemical Society

This paper is open access.