Science Friday - Long-Term COVID Effects, Dicamba and Agriculture, Mosquitoes. July 24, 2020, Part 2

Episode Date: July 24, 2020

Since the beginning of the pandemic, hospitals have been treating and triaging an influx of COVID-19 patients. Hundreds of thousands of seriously ill patients have been hospitalized, with some having to stay and receive care for months at a time.   But now as some of those patients return home, hospitals are opening post-COVID clinics to help with their transition. Health care professionals are monitoring the recovery process and taking note of persisting health issues from the disease. Mafuzur Rahman, clinician and leader of the post-discharge COVID-19 clinic at SUNY Downstate in Brooklyn, New York, and Margaret Wheeler, a physician at the Richard Fine’s People Clinic at San Francisco General Hospital, talk about the health effects they have seen in their patients and what patients may need for recovery. A federal court in California recently vacated the three popular dicamba herbicides—Xtendimax, Fexipan, and Engenia—after the court determined the EPA violated the Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA) by registering the chemicals for use. Environmental advocates rejoiced, while farm groups lamented the decision as yet another hurdle for farmers to overcome during a difficult year. More herbicides could face legal challenges in the coming years. But they were once part of a golden era of U.S. agriculture, and a key player in the rise of modern industrialized growing systems. There are over 3,000 mosquitoes, but only a handful feast on blood, like the yellow fever mosquito, Aedes aegypti. Other mammals also have blood running through their veins, but are bit less frequently. So why do mosquitoes love humans so much? New research on these bugs look into the cause, investigating mosquitoes’ preference for certain mammal odors and human population densities. Another paper examines a potential gene solution to decrease mosquito bites—thus lowering transmission of mosquito-borne diseases. Joining Ira to talk about the latest research and more mosquito science is “Lindy” McBride, biology assistant professor at Princeton University and Jake Tu, biochemistry professor at Virginia Tech. Subscribe to this podcast. Plus, to stay updated on all things science, sign up for Science Friday's newsletters.

This is Science Friday. I'm Ira Flato. A bit later in the hour, hundreds of thousands of COVID-19 patients have been hospitalized. We'll talk about what some of the long-lasting impacts might be and what recovery might look like for them. But first is time to check in on the state of science. This is KERNO. St. Louis Public Radio News. Iowa Public Radio News. Local science stories of national significance. Last month, a federal judge ruled a popular group of herbicides can. no longer be used by farmers. This is considered a win for environmentalists. These are strong chemicals

and have the tendency to stray from where they're sprayed. But some farmers say this ruling is a slap in the face for them, and a bureaucratic nightmare has ensued since. Here with us to talk about this story is Christina Stella, Harvest Public Media Reporter for NET. That's Nebraska's Public Media Service. She's based in Lincoln, Nebraska. Welcome back to Science Friday. Thanks for having me, Ira. Let's begin with what herbicides. What are the herbicides that are affected by this ruling? The three chemicals that have been affected are Ingenia, Extendomax, and Phypam,

which are three popular dicamba herbicides. So walk us through what the big deal is about the dicamba herbicides. Yeah, so dikamba is a very common chemical found in herbicides that a lot of farmers use on their fields to control their weeds. It's actually been around for several decades and was developed in what some experts call a golden age of agricultural innovation in the postwar era. And so while Daicamba played a key role in the rise of industrialized agriculture, there are also some concerns that the chemical can be harmful to native plants and grasses and that its use contributes to weed resistance. And tell us what the ruling was and how it affects that. So the judge made the decision for several different reasons.

The ruling effectively removed the label for use off of those chemicals. And so the judge agreed with the plaintiffs that the registration of the chemicals violated certain federal environmental law and also didn't really acknowledge different risks that the dichamma products pose to the environment and farmers' livelihoods. Monsanto plays a role here too, doesn't it? So Monsanto developed one of those dichanba systems that was banned, the Extendomac system, which something like 60 to 75% of soybean farmers have switched to over the past few years. So it's a very widespread product. Now, the issue with it is, dichamba usage has caused tensions in a lot of different farming communities across the country because of something called dicamba drift. Now, during spring season, farmers have to be really careful when they're applying those.

chemicals. You have to have the right equipment to do the job safely. The wind speeds has to be right, the temperature, or else that product can drift over to your neighbor's property and it can wipe out their crops. And that's a pretty devastating financial risk. One of the farmers that I spoke to explain to me that sometimes if there's an accident, neighbors will try to work it out amongst themselves. But plenty of other times, farmers have a hard time putting in a complaint to the state and getting a restitution for that loss. So, you know, in one extreme case that comes to mind, a farmer shot and killed his neighbor over dicamba drift. So there's been a lot of tension there. And just a couple weeks ago, Bayer agreed to pay $400 million in dichamber drift settlements that

they inherited from Monsanto when they purchased the company in 2018. So there is a history there, and a lot of people have been impacted by DiCamba Drift. And then, To the monopoly point, because of that drift risk, a lot of farmers have felt pressured to purchase the extend package from Monsanto, which would have those dicamba resistant seeds. So they eliminate potentially losing their crops if their neighbor makes a mistake. So in the eyes of the court, the EPA didn't take those social and economic risks into perspective, which, I mean, they're really tied up in each other in a lot of ways. and they didn't take that into account when approving the products for use. So was this ruling a surprise to people you talked to? Oh, yes. It caused quite a stir in the agricultural community.

So, you know, plenty of people have been watching this case since the original lawsuit was filed in 2017. But what really surprised people was the timing. News of the decision broke in the midst of spring season. So a lot of farmers had already started using these products or they were about to. And that's difficult because producers make their chemical and seed decisions a while in advance, I mean, a year in advance. So for farmers like Tracy Zip, who I spoke to for the story, it was really destabilizing not to know whether she'd be able to protect her crops and potentially having to come up

with a plan B completely on the fly. I think that was a really stressful situation for a lot of people to work through. We have a little recording from Tracy Zip who grows soybeans, corn, sorghum, and wheat in Nebraska, and this is what she said about the weeds. They produce like 5 million seeds per plant. You can't let them grow in your field. So you have to walk in, chop them,

carry them back out of the field, and burn them. So it sounds like getting that camo on her farm is a big deal for her. Oh my gosh, yes. You know, she relies on those kinds of chemical tools to control weeds on her farm. farm. And that's the norm in commercial agriculture. You know, as I said, those annual planting and resource decisions, they happen months in advance and they really revolve around the question of, okay, what seed system am I going to use, you know, what are my neighbors using, and what chemicals

complement them. So if she truly had not been able to use those products this year that she had purchased, that she had spent thousands and thousands of dollars on, by the way, I can't imagine how she would have gone about hiring people on such short notice to weed thousands and thousands of acres by hand, especially in the middle of a pandemic. So I think that that's definitely something we talked about, too, that this year in particular there was that added stressor there. And, you know, in a world where those herbicide options are already dwindling because more and more weeds are becoming resistant to various chemicals, farmers are very anxious to make sure that they can use what, works for as long as they can. So it's definitely a big deal to them. And it sounds like a lot of the states didn't know how to respond to this ruling, and there's sort of a jumble of responses. Yes. You know, the decision confused a lot of state agriculture departments because, you know,

the way it works, these products, they have a federal label for use, and then they also have a state label. So even though the ruling was, you know, effective immediately per the court, a lot of local department said, okay, well, hold on now. These products are certified for use in our state through the end of the year. We're going to honor that labeling. We're going to continue to allow people to use them until the EPA provides more guidance for us. And the agency did, after a few days, issue a cancel order for those products, you know, meaning you can't buy or sell them anymore. But, and farmers were happy about this, they were still allowed to use whatever they had already purchase through the end of July, which is when most people would be done spraying anyways.

So that was kind of how they softened that decision for farmers. Do you get the sense that there is this tension? I mean, I get that sense between farmers and agencies like the EPA. Absolutely. Yeah. I mean, obviously farmers are not, they're not a monolith, but I do think it's fair to say that a lot of commodity farmers are sensitive to this kind of federal intervention. because they see it as a financial risk for them, not to have those tools.

You know, there's a lot of pressure on farmers to maximize their production, to increase that yield as much as possible because commodity prices are so low and they really have to produce as much as possible to sustain themselves financially. And in this case, there was a perception among some that the courts and agencies like the EPA were almost like playing around with their livelihoods. by making the decision, particularly at the time that they did. And so I really get the impression that it was seen as inconsiderate and kind of stemming from a misunderstanding of, you know,

farmers' time and schedules and the labor that goes into making these decisions. Could we see this reversal of what herbicides are approved for use? Could we see this extending to other herbicides that farmers might be using? Absolutely. I mean, it's certainly possible this. ruling could play into the court's decision in future cases because it could be used as precedent. But interestingly, Bayer, Corteva and BASF, which produced the three dicampa herbicides that were just banned, they actually have appealed that ruling. So the dicamba saga is not fully over yet,

but this very well could create a window for future similar cases. And I guess if farmers feel that they look down the road and they see there might be similar cases and it really has upset their farming system of using chemicals, maybe they're finding nonchemical ways of dealing with the weeds. Yeah. I mean, I think that right now in the United States, farmers in the United States are still very much operating under the system of, okay, what chemical system am I going to use? But depending on how many lawsuits we see in the timeline of decisions, yes, that absolutely could be a question that they are forced to confront sooner rather than later within the next decade or so, I would say. You know, there are already those mounting questions about weed management.

And in other countries, farmers have already been forced to address that question. So in Australia, for example, there are some years ahead of us in terms of herbicide resistance. So people have had to invest in machines, like an attachment to the combine that destroys weed seeds or collects them. and they have those in addition to using the herbicides that still work for them. Given my conversations with Bob Hartsler at Iowa State, who's a weed specialist, we won't see a situation where there's no herbicides being used, at least not any time soon, but they will need to start adding other tools and methods on to sort of compensate and extend the life of the herbicides that still work.

And in other countries, you know, farmers have had success with that. So in his words, the outlook is not total doom and gloom for producers, but it is a shift that will have to happen in the States eventually. I guess you have to plant the seeds with farmers about that because they may not be so in favor of that kind of solution. It's interesting to say that because in Bob Hartzler's view, farmers are not going to want to make that change because more than anything else, it's just a significant investment.

It's a pretty big change. the way that they're used to doing their work. And I think that in a lot of cases to switch over to this technology, I mean, that's, we're talking hundreds of thousands of dollars in new equipment. But again, producers are resilient people. And from what I've been told one day, they're not going to have a choice. That's all the time we have for now. I'd like to thank my guest, Christina Stella, the Harvest Public Media Reporter for NET, Nebraska's Public Media Service. She's based in Lincoln, Nebraska. Thank you, Christina. for taking time to be with us today. Thank you so much for having me. And we're going to take a break,

and when we come back, we're going to look at what we know about the long-lasting health impacts of COVID-19. So stay with us. We will be right back after this short break. I'm Ira Plato. This is Science Friday from WNYC Studios. This is Science Friday. I'm Ira Flato. Since the beginning of the pandemic, hospitals have been treating and triaging an influx of COVID-19 patients with hundreds of of thousands of seriously ill patients being hospitalized, some for up to months at a time. But now, some of those patients are returning home, and hospitals are opening post-COVID clinics to help with their transition. What have health care professionals learned about the symptoms and long-lasting health effects? What might the road to recovery look like for individual patients?

That's what we're going to be talking about with my guests who are here to fill us in. Dr. Maphazzo Rahman is vice chair of medicine and leader of the post-discharge COVID-19 clinic at SUNY downstate in Brooklyn, New York. And Dr. Margaret Wheeler is a physician at the Richard Fines People's Clinic at San Francisco, Professor of Medicine at UC San Francisco. Welcome to Science Friday to both of you. Thank you. Thank you for having. Dr. Rahman, a month into the pandemic, Sunni Downstate became a COVID-only hospital.

Is your hospital in a hotspot area? Yes, even our zip code has one of the, in New York State, one of the highest mortality rates, one of the highest incidence of COVID-19. So we would be by many definitions for one of the major hotspots for this pandemic in the last few months. And Dr. Wheeler, you work in an outpatient setting. What is the treatment and care that you give to COVID patients coming in? In our outpatient clinic during the height of our search and still even yet, we were the non-COVID hotspot place. So anybody who was thought to have COVID symptoms went elsewhere.

But of course, we saw many people coming in with COVID who had unsuspected COVID. And then we have a large primary care panel that we follow. And so all of those folks, anybody who got COVID, we were calling them, helping them isolate and then caring for them, hospitalizing them, and then caring for them afterwards. But my clinic is at San Francisco General Hospital, we're the safety net hospital for San Francisco. And although San Francisco has not been hit at all like New York, I think largely having to do with our public health closed down very, very early, we do care for the population in San Francisco have been the hardest hit. So for us, of course, it's the

poor, but it's the Latinos that have been hit the hardest are the highest rates of hospitalization, and those are the patients that we care for in my clinic and at San Francisco General Hospital. So what happens after you have your patients? What happens after they're released? Who takes care of them? We care for people as they come out of the hospital. Some of them come out requiring oxygen still. many people with continued symptoms. As you probably know, COVID-19 causes a very inflammatory state. So many organs can be affected. And so people come out needing to be on blood thinners because they've had blood clots go to their lungs or they've had strokes. People come out having worsened heart failure. So worsened kidney failure. COVID-19 can cause such a damage. devastating effects to many organs. And of course, people who have gotten COVID-19 and gotten sick enough to be hospitalized, many of them had, you know, diabetes and heart failure and lung disease beforehand, and now things are only worsened. And then finally, I would say even those who

are not hospitalized, many people have long-lasting effects. And I think that's one of the interesting things about this disease is that it's such a huge spectrum. And some of the long-lasting, long-lasting effects. People talk about huge fatigue, the aches, the weird lancinating pain, the sore throats, just a myriad of symptoms that continue to plague people. Sometimes we've been seeing months afterwards. I don't know how long some of those symptoms are going to last. Dr. Rahman, do you see those same sort of long-term effects on the patients? Oh, yes, absolutely. As Dr. Willer said, this disease is kind of teaching us. new things every day. As we think today, we have a handle on the potential complications from

the virus, the side effects that our patients should be watching out for. Then a few days later, a few weeks later, we realize that, you know, this virus can cause other things. As Dr. Rillo also said, every organ in the body, brain, the lungs, the heart, the kidneys, the gastrointestinal tract, the skin, the nerves, nothing is spared, it seems at this point. And the impact isn't necessarily just the virus that's doing it? It's also the body's own immune system, which is actually a good thing, and we need to have our immune system ramp up once the body detects an infection. But in this particular situation, I think we are seeing the immune system itself, when it's not controlled, sometimes people call it cytokine storm, that itself causes devastating conditions

and situations and illnesses in our patients. And we are seeing our patients who we thought were better or getting well, then subsequently we are finding out that, you know what, the disease hasn't completely gone away. Some people have come back in weeks, months later, and we're finding out that the lungs are not normally yet. They still require that oxygen supplementation. Some of them might have gotten worse. So those are all sort of like the medical thing that we are seeing, but mental health is another thing that we have been really worried about our patients from the get-go, and we're finding out that especially, especially in our area in Brooklyn, New York,

in a socioeconomically underserved area, a lot of our patients may have issues, the pre-COVID, but probably was subtle enough that they were functioning, but once you're in hospital for weeks, months, in an isolated setting, you are not normal anymore. The devoid of the human contact,

not being able to see the loved ones, the doctors, the nurses, we all, we had more masks on, or gowns on our now that we let them go and they go back to the society where other people in the society, family members, friends are not interacting with the same patients even the same what they did in the past. So these patients are not like they came to the hospital, they got treated and you go home and life as usual. That's not happening. So some of those people who probably have subclinical depression or PTSD now those are things are manifesting and we have social

workers, trained mental health workers. Maybe initially our main concern was treating the lungs, those kidneys that failed, providing dialysis for them. Yes, we did that. But a big portion of the people's mental health were kind of not our priority, but we're finding out, you know, those things are long-lasting. People are suffering gravely, and it's not just physical illness. The patients that I have seen are also very worried about contributing. to infection in their communities and their families. They may be even self-isolating, even as they're suffering from isolation.

And in our community, the majority of people, as I said before, who are getting this illness and are getting gravely ill are Latinos and Latino men. And it's not just the isolation, but the loss of some of their role as provider for their families. I had one patient that I saw who had been in the hospital for months.

He had suffered many, many different complications, blood clots and that kind of stuff, and had had to have a tracheostomy, which is a little tube that's put in your trachea in your throat to help you breathe. And he said three things. The first thing he said was he thanked us for caring for him. The second thing he said was that what had gotten him through was his, faith and the love of his son. And the third thing he asked was, when can I go back to work? Seeing him there and knowing that he was not going to go back to work for months,

that was a huge blow to him. And so I think, you know, being able to carry out the roles that give meaning to your life is huge and continues. And will only worsen the issues of food insecurity. and financial stress and those kinds of things that we're seeing in the communities that we care for. Dr. Rahman, why did you establish the clinic? What can you do at the clinic that, let's say, a regular hospital cannot do? One of the reasons we wanted to open the clinic is during this height of the pandemic in New York, many of the doctors' clinics in the community were closed. Doctors were not seeing their patients.

They were trying to reach patients over phone and do telemedicine visits and so forth. We understood that many of the doctors had not seen a truly sick COVID patients and cared for them. Those doctors also may not have the facilities. Every type of providers that you can think of we have in our hospital. And since we took care of those patients, we knew what the patients went through, what the complications were, the treatment plan. In our community, it's a place where many of our patients don't have private doctors. They don't have regular primary care provider PCPs that they go to routine.

Now, they were infected with a virus that a lot of people are afraid of catching. So a lot of the doctor's clinics were closed. Now, where would they go? And we treated our patients. So we wanted to make sure that our patients had an outlet. We need to be able to give them information that's helpful, that's supportive and at the same time provide counseling to the family members as well. If the family has a question that can call us and say,

hey, no, my father just came home, how should we interact with him? Should we use the same bathroom? Should we, you know, where PPE is? We need to learn from our patients so that we can educate others. We can do better for the next patient that comes along when they ask like, what happens next? What do we tell them? We can tell them based on our experience,

based on our information from other patients, tell them this is what we're seeing, this is what we're learning, and we will have more information later and so forth. So having that clinic kind of provided us with the outlet of helping our patients at the same time helping us understand the disease itself so that we can take future actions. Dr. Wheeler, you know, it sounds to me like the patients who get discharged after months, they're going to have medical bills, they're going to have counseling needs, they're going to have social service needs. It all boils down to the way I look at the large envelope of this is money. These are big questions. I asked the question because, okay, we have COVID-19 now, but we have suddenly, you know, woken up to the idea, hey, there are,

there are a lot of bad things going on in diseases around the world? This is not going to be the last disease or possible disease that comes and hit us. Should we set something up that it's a little more permanent in place. Absolutely. And we need to expand the public health abilities in this country, which has long been underfunded and really actually throughout medical history, it's not so much the individual care that has caused the greatest gains, but public health measures like clean water,

things that we have isolating and contact tracing and that kind of thing. So we do need to beef those up. It is going to cost money. We'll just need to have the. political will to pay for some of those things, which will in the long run, I think, really put us on more stable economic and medical ground. I'm Ira Plato, and this is Science Friday from WNYC Studios. I have just one more question because lots of people have asked this. Lots of people who were suspected of having COVID-19 were told to stay home, and they became known as these

long haulers. They have lingering symptoms, but they, they may may not have received a positive test like Charlie, who is 30 years old and from San Francisco, and left us this comment on our Vox Pop app. My name is Charlie, 30 years old from San Francisco. I've been dealing with post-COVID symptoms for four months. I've been dealing with shortness of breath, heart rate issues, chest pain, muscle twitching, etc. I've had all these tests done.

My doctors don't know what's wrong. I don't know what's wrong. This has been so debilitating, and I still have no clear outlook. And they are sort of in limbo. I mean, how do you provide care for them, Dr. Rahman? That is actually a significant problem. In my area, for example, initially patients who were not in need of being hospitalized, meaning they were doing well enough that they could go back home.

We didn't test them because we didn't have enough test kits. They're worried. What's going to happen to me? It tells me what's wrong with me, and I'm going to doctors and I'm not getting the care. So first, reassuring them and saying, you know what, we believe you. You have a COVID-like-you-less, and let's start there. And then look at the symptoms, maybe collectively, if it's possible or individually, and try to provide a treatment plan. And the treatment plan can be with medicine, can be with counseling, can be with reassurance, with blood tests, and so forth.

And as we learn, as providers, we learn more about COVID-19. We are going to keep our patients in the loop. So when the patients hear that they're not alone in it, they're not abandoned, they are with us, and we are with them. I think that provides reassurance, and I think that's a start. The symptoms that people have are protean. We don't always understand, oh, is that hearing loss? Is that COVID, or is that just hearing loss that you're having,

or whatever the symptom happens to be, it can be tricky. And so I really feel for Charlie because patients don't know, oh, what terrible thing do I have? Is this COVID or is it something else? And lots of times we doctors don't know either. And so we're doing the kinds of complicated workup because we can't just assume, oh, this is all post-COVID. And as we learn more, we may find out that, I don't know,

COVID causes you not to absorb some vitamin or something else like that. and then we'll need to be treating those things because we're really an evolution of understanding this disease and a spectrum and the kinds of things that we might be able to do to shorten these lingering after effects and understand them better. So everyone who leaves the hospital after getting COVID-19 and they're able to walk away spends the rest of their life as sort of a test case because we really don't know what the long-term effects are. We don't know.

To a degree, yes. Yeah, we don't. And so the more and more people hear that there is more of an anxiety provoking this situation becomes. So there are some people died of COVID. Some people like that Willa said had nothing to do with COVID. That chest pain probably is a heart attack because of the line diseases to begin. Right now, everything is COVID. So reassurance from us letting patients know that we are in it together.

We will do the very best we can. we are all learning from this, and we will be learning, I think, for quite some time. Well, we have run out of time. I'd like to thank both of you for a very interesting discussion. Dr. Maffazo Rahman, Vice Chair of Medicine and Leader of the Post-Discharge COVID-19 Clinic that's at SUNY downstate in Brooklyn, New York. Dr. Margaret Wheeler, a physician at the Richard Fines People's Clinic at San Francisco General Hospital and a professor of medicine at the University of California in San Francisco. Thank you both for taking time to be with us today.

Thank you for having me. Thank you very much. In our Science Friday Vox Pop app, we want to continue the conversation about the long-term effects of COVID-19 and long-haulers. So we're asking, have you been sick with the virus for months? Tell us about your experience and your questions that still remain unanswered. That's on the Science Friday Vox Pop app wherever you get your evidence. apps. After the break, we'll be talking about a summertime staple mosquitoes and why they prefer

to bite us, and the ways that scientists are trying to get them to stop doing that. This is Science Friday, I'm Ira Flato. You know, there are some things that just remind you of summertime, heat, cicadas, and unfortunately, mosquitoes. Stay outside late enough, and you might become their dinner, for some mosquitoes at least. But why? Why do they love us so much? Last time I checked, there were more non-humans on the menu. Well, new research on these bitey bugs looks at two big things, why we have become the main course for some mosquitoes,

and how a gender swap might fix the problem. Joining us today is Lentie McBride, an assistant professor in the Department of Ecology and Evolutionary Biology at Princeton University, and Jake, too, professor in the Department of Biochemistry, at Virginia Tech. Linde and Jake, welcome to Science Friday. Thank you. Thank you. Lendy, before we talk about why mosquitoes seem to prefer we humans, let's talk about why we humans showed up on the mosquitoes menu in the first place. Excellent question. Most mosquitoes are fairly opportunistic,

and they'll bite many different types of organisms with which they come into contact. But a few species, just a few of 3,000 species have evolved to really specialize in biting. humans. And people have speculated for a long time as to why that might be true. And we set out to collect some systematic data to support some of those hypotheses. And where did you go to do your collection? We collected mosquitoes in Africa. We were focused on the species 80s Egypti, the main vector of dengue, Zika, Chicangunya, and yellow fever. And this species originally evolved in Africa. It was previously known that African populations of the species are likely ancestral and not necessarily interested in biting humans, but at some point in the past five to 10,000

years, certain populations, somewhere in Africa, evolved to specialize in biting humans and then escaped and spread around the world. So outside of Africa, this species loves biting humans within Africa, no one had previously found those sort of first human-preferring populations, and it was thought that most of these mosquitoes in Africa did not like humans. So you went over to Africa and brought back some mosquitoes? Yeah, exactly. A really talented postdoc in my lab, Noah Rose, collaborated with several African researchers in various countries, and Noah went to six or seven different countries, and in collaboration

with these other researchers, collected mosquito eggs. at 27 different locations spread across sub-Saharan Africa from the East Coast to the West Coast. Just as a point of reference, how do you get mosquitoes through customs? You say, hey, I've got a whole bag full of mosquitoes here you ought to know about? Sometimes we do just to avoid problems. The great thing about this particular species is that the eggs are adapted to survive dry periods by becoming dormant. And so if we trick the eggs into thinking that it's the dry season,

we can get them to enter this resting phase, and we can basically just put them in our hand luggage and bring them back. And we show them at customs. We have a special permit, and they wave us through. A pro tip for anybody wanting to bring back mosquito eggs. So you bring back the eggs to your lab, and after the eggs hatch, you give the mosquitoes a choice, human or guinea pigs. How does that choice come about? Well, we needed some sort of non-human animal, and guinea pigs are small, friendly, cute. They fit in our olfactometer, we call it. And previous work had shown that they were attractive to these animal-preferring mosquitoes. We also sometimes use a quail because quails are very different from guinea pigs.

So the fact that these mosquitoes respond the same to guinea pig and quail gives us a good idea that the behavior isn't guinea-pig specific. We're talking about non-human animals in general. And so that's when you figure out that the mosquitoes have different preferences. Yeah, so Noah would put 50 to 100 female mosquitoes in a box at one time and turn on a fan that pulls air over a guinea pig and over a human. So the mosquitoes get to choose. Do you want to fly towards the human-scented air or the guinea-pig-scented air? And they sort of show us by numbers what they prefer.

And do they have different preferences depending on where they were collected and their climate? Yes, and that was the really surprising and interesting thing is that we found that throughout most of sub-Saharan Africa, these mosquitoes tended to fly towards the guinea pig. Sometimes they made a very strong choice for guinea pig, especially in places where there were a few people and in places that were relatively wet with dependable rainfall. But in really seasonal environments where there's a long, hot, dry season, those mosquitoes loved humans. Does that mean my backyard, my... swampy maybe Everglades or my swampy backyard in the heat in the summer, I'm safer because it's

not hot and dry? Unfortunately not. This only applies to this species and it only applies to the species within Africa where it originally evolved. Outside, so if you live in Florida, for example, you'll have the same species, probably southern Florida at least, in your backyard. And they will very likely be human preferring despite the wet human conditions. From that handful of mosquitoes, is it true that it's the females that need the blood, Lundy? Yes, females need blood to make eggs, essentially. Males do not bite. And Jake, that's where you come in, because you were looking at a way to turn the females into males. Yeah, exactly, because we are pretty interesting in this particular topic because, as Lindy was saying, only the females bite.

And so only females are able to transmit disease-causing pathogens like viruses and parasites. So there's really a potential for us to control mosquito-borne diseases if we can understand the sex determination pathway better. So we can manipulate the sex ratio. Were you able then to swap out genetic material from a female and make it into a male? Right. It's really not swapping out. It's basically adding in. Right.

So because in mosquitoes, at least this particular mosquito, the presence of a male determining locus established male sex, just like in humans. Like say, if you have why in human, you become a male, right? So that extra male determining locust determines male sex. So what we did was we actually put a gene or inserted a gene that's called Nix, which we know is a male determining factor. into a part of the chromosome that can be inherited by both sexes. So now the female had a chance to acquire this Nix, and then they were converted into fertile males. So then you really didn't have to get rid of the whole chromosome.

You just had to put in a little bit or take out a little bit of a gene in there. Yeah, just one gene, right? So only adding this Nix gene into the female genome. So the females are still females in terms of the genetics, right? So they don't have the am locust or the Y, right? But they acquired this just one gene, and they were able to be converted into a male that are able to mate and produce progeny. And you were able to mate the males with the females and test this out?

Right. So these females are actually converted females, right? So they are, genetically speaking, they don't have the M locusts of Y. but they were able to mate with the wild type females producing converted males as well as wild type females. But I understood there was sort of a, I hate to use this point of, a fly in the ointment here and getting these newly genetically modified males to mate. Right, exactly. As I said, you know, there's this male determining locusts, right, determines the male sex.

that locus has multiple genes, like 30 genes. So by just inserting this nix into the females, we did not bring the other genes that's in the M locus. So it turns out there's a gene called myos in the m locus or male-determining locus, and that's required for flight. So we know that because when we knocked out this myosax gene in a wild type male,

wild type male, you know, lost flight ability. Right. So now because we only inserted nix into the female genome, not myosex, these females are not able to fly. And flight is actually required for mating. So what we have to do is we have to help this converted male a little bit by chilling the females down. So you put the females in the freezer?

Fridge. Yeah, fridge. Excuse me. I didn't want to go too far with that. You refrigerated the female so that they would sort of slow down and could be caught by the males who can't fly. Is that basically it? Not exactly. Because so it would kill them down so the females will not reject these males, right?

So if they're alert, you know, this mating won't happen. So the males and females really have to detect each other's when, you know, windbeet frequency and a lot of things going on. That's not my area of expertise. but lots of things are required for the mating to occur. So this is just to chill the female down so they don't reject the male. Well, if you had that little problem with them flying, how do we know then that they will actually bite or mate out in the wild? Right.

So the males don't bite anyway, right? So these converted male would not bite, right? But in order for them to be competitive in the wild, so the one idea was to introduce both genes, the nix and mild sex, into the female. So now you have a fertile and flying male, and that's the hope. And we're not there yet. So what is your next step if you're not there then? You have to find a way to allow them to fly. Right.

So basically we're trying to do what I just said. try to insert both genes into the female genome. Lindy, what do you think of all of this? I think it's fascinating. I just love how biology cooks up these amazing things. I would have never guessed that there would be a separate gene for male morphology and male flight. What could possibly go wrong with this if we release these mosquitoes in the wild? Would it be better than pesticides, do you think?

For one thing that these genetic approaches requires mating. We're targeting this particular species that invaded the Americas a few hundred years ago and causing problems to humans. And so that's one of the advantage of this type of approach. Of course, as I said earlier, we're still far away from even testing this in the lab cages. So a lot needs to be done. And Lindy, think this is a good way of doing it. Yeah, you know, I think we need to try all the ideas that we have.

And I think this is a promising one that is exciting to be this far in developing this type of approach. It's one that we certainly need to try. You know, people will say, why do we need mosquitoes in the first place? There's such nuisances they carry around these diseases. They spread them around the world. How do you answer the question, why do we need mosquitoes at all? Why don't we just wipe them all out, Lundy? Mosquitoes are a really important part of the food chain.

So if you like to fish, a lot of the fish that you catch, probably mosquito larvae, birds and bats eat a lot of mosquitoes. So I'm not a mosquito ecologist, but I would be afraid of what might happen if we got rid of all mosquitoes. Jake, you agree? I would just add, like, there are more than 3,000 species of mosquitoes, right? So I don't think anybody is trying to wipe out all 3,000 species of mosquitoes. And so what scientists are trying to do is to control the population of a few specific species that are causing lots of problems to humans.

Just a quick note that I'm Iroflato, and this is Science Friday, from WNYC Studios. Okay, so let me give you the Science Friday blank check question. I'll give it to both of you. Let me give it to you, Lindy, first. If you had a blank check like I have or I don't have in my back pocket, and you could spend it on any kind of research or any technological whiz-bang thing you'd like to invent,

what would you do with it? I'm really interested in understanding how this mosquito finds us in the first place, how it recognizes the way we smell. So one of the first things I would do with that money is to dive into the mosquito brain and figure out exactly how it works. That is an interesting. We don't know that yet of all these years of research?

It is surprising. You know, we know remarkably little about what it is specifically about human odor that these mosquitoes love. I mean, we know some things. There's no one compound that will attract these human-preferring mosquitoes, you need combinations of compounds, odor blends in order to attract the mosquitoes. But it's still, I'd say, largely a mystery. Do we know what keeps them away, like Citronella candles and things like that?

Are those real, do they really work? Yeah, citronella works. Deit, which most people would be familiar with, is extremely effective. But that's another surprising thing is we've only really recently begun to understand how deep works. Deet was discovered in just sort of a random screen of thousands of chemicals. Someone was looking, the Department of Defense actually was looking for a chemical in the middle of the 20th century that would repel mosquitoes. And they stumbled across Deat. And it's only recently that we understand how it works. So like I said, there's a lot of mystery still in mosquito's

sense of smell and what pushes them away and pulls them towards humans. And Jake, what would you do with the non-existent cash? Yeah, so while we talked about applications we could pursue, right? So the potential application, because we still have a long way to go to have something that can be tested in the lab. But I'm also quite interested in the fundamental biology, right? So as a scientist, I work towards mosquito control, but also I appreciate the biology of these organisms and it's really, really fascinating.

So for example, we know Nix is the switch or the master's. to switch, you know, to put or set the embryo onto a pass of male development. But how does it work? You know, what does it control? What are the other genes that's evolved? And then the other question is that how is this evolved, right? And within the mosquitoes. And so those are really fascinating questions to me.

I'd have thank both of you for taking time to talk with me today. Lindy McBride, assistant professor in the Department of Ecology and Evolutionary Biology at Princeton University. And Jake 2, professor in the Department of Biochemistry at Virginia Tech, thank you both for enlightening us about mosquitoes. Thank you so much. Yeah, thank you. Linde McBride leaves us with one pro tip for dealing with the pain of a mosquito bite.

After being bitten 2,000 times by mosquitoes, Dr. McBride says that the best treatment you can do for that pain and itch is hot water. Put hot water as hot as you can take. it on the mosquito bite. The heat and pain sensors in your brain sort of cross over in the area so the heat of the hot water cancels out the pain of the bite, so you forget about it. Hope you share that tip with your friends this weekend, because that's about all the time we have. In case you missed any part of this program or you'd like to hear it again, subscribe to our podcasts or ask your smart speaker to play Science Friday. And you can also say hi to us on

social media, Facebook, Twitter, Instagram, or email. Our address is SciFry at ScienceFriday.com. Send feedback, yes. Tell us what you would like us to cover, always looking to hear from you. One last thing before we go, something very exciting. Starting Monday, August 3rd, we're hosting our first ever virtual conference for educators, the Science Friday Summer Institute. So educators, join us to connect your teaching to the stories of scientists.

to collaborate with your colleagues. Here's how to do it. Go to ScienceFriday.com slash Summer Institute to learn more and grab your tickets. That's ScienceFriday.com slash Summer Institute. Have a great weekend.

We'll see you next week. I'm Ira Flato.