Mosquitoes and their itchy bites are more than just an annoyance. They transmit dangerous viruses with deadly consequences—making them the most lethal animal on Earth. It’s the Aedes aegypti and Aedes albopictus mosquito species that are behind outbreaks of dengue virus, Zika virus, yellow fever virus and chikungunya virus, responsible for over 100 million human cases around the world annually. And they’re expanding their habitat around the world as the global climate warms, bringing them into contact with more potential victims who have less immunity and increased susceptibility to these mosquito-transmitted viruses.
A vaccine can provide the recipient with immunity to one or two of these viruses at a time. But there’s another way to tackle these diseases: by going after the insects. Targeting the mosquito population as a whole or their ability to transmit disease takes aim at all these viruses at the same time.
As the United States enters another mosquito season, mosquito control districts in Florida and California are preparing new strategies to combat mosquitoes and the viruses they transmit. They’re trying out one of two new mosquito management methods made possible by a bacterium called Wolbachia pipientis.
A bacterium that’s our enemy’s enemy
Wolbachia are bacteria naturally found in insects throughout the world. They live inside a host organism’s cells. From there, Wolbachia are able to manipulate their host in many ways—things like increasing the number of eggs a host lays or even changing the host’s sex from male to female by manipulating its hormones.
Researchers discovered in 2008 that Wolbachia in fruit flies protect their hosts from fruit fly viruses. That realization got them wondering: Could Wolbachia also protect Aedes aegypti mosquitoes from viruses that cause human diseases?
Aedes aegypti mosquitoes don’t naturally carry Wolbachia. But consistent with the fruit fly studies, when researchers infected Aedes aegypti in the lab, the viruses they carry replicated less. Fewer of the infectious bits of the disease-carrying virus inside the mosquito meant disease transmission was limited—they were less likely to be passed on when mosquitoes fed on their prey.
Researchers in Australia, the United States and elsewhere are currently investigating the reasons Wolbachia limit viruses. Some hypothesize Wolbachia improves the mosquitoes’ immunity to the virus, while other research, including my own, suggests Wolbachia steals key nutrients the virus needs. Both may be true.
The real need to employ this strategy now is motivating field trials to release Wolbachia-infected mosquitoes in several regions of the world.
Vector competency: the female approach
Only female mosquitoes bite and transmit viruses. Thus, the most powerful approach to reducing virus spread is limiting viruses in the female mosquito.
Wolbachia bacteria are transmitted from mother to offspring. If you introduce Wolbachia-infected female mosquitoes to a population, all offspring will have Wolbachia—and therefore be less likely to transmit disease-causing viruses.
This strategy is used by the Eliminate Dengue program, a nonprofit collaboration employing seven research institutes around the world. In test areas, Eliminate Dengue has successfully incorporated Wolbachia into mosquito populations.
In this context, an interesting aspect of Aedes aegypti behavior is their tendency not to travel far. In fact, a highway is a sufficient barrier to prevent mosquito spread. When researchers set up a release site in one city or town, they don’t see their mosquitoes travel to other areas.
This allows for controlled studies, as well as the release of these mosquitoes only where it’s been approved. The limited spread and isolated sites used were important factors in the decision to allow mosquito releases in the United States.
Eliminate Dengue is not yet active in the United States. Instead, the United States is taking a different approach, looking to male rather than female mosquitoes.
Population control: the male approach
MosquitoMate is a company developed out of the University of Kentucky in Lexington by medical entomologist Stephen Dobson. Partnering with the Florida Keys Mosquito Control District, they started the release of 40,000 Wolbachia-infected male mosquitoes per week this spring.
The strategy relies on a phenomenon called cytoplasmic incompatibility to reduce mosquito populations. CI occurs when a male mosquito infected with Wolbachia mates with an uninfected female. Because Wolbachia is transmitted through the female egg, the offspring will be Wolbachia-free. But Wolbachia has already altered the father’s sperm DNA in a way that allows offspring to survive only if the fertilized egg has Wolbachia. Since the infected males will come in contact only with the naturally occurring Wolbachia-free population, their offspring will die during embryonic development—the eggs won’t hatch.
And, unfortunately for the mosquitoes, females store sperm inside them to continuously fertilize their eggs. This means that the female mosquito’s first mate will be the father of all her offspring. So even if a female just mates again, once she’s partnered with a Wolbachia-infected male, all her offspring will not be viable.
The Florida Keys Mosquito District is not limiting its attack to just one approach. Beyond Wolbachia and more traditional strategies, they’re also partnering with Oxitec, a genetic engineering company. Like MosquitoMate, Oxitec also releases male mosquitoes. But, in place of Wolbachia, Oxitec genetically modifies its mosquito to contain a self-limiting gene that causes offspring to die.
The goal remains the same: Release males into the environment that will mate with females and cause all offspring to die, eventually leading to a mosquito population crash.
Male and female strategies share one goal
Each Wolbachia mosquito strategy has its strengths: The female approach is broad-reaching and should directly decrease disease transmission. The male strategy effectively lowers the local mosquito population, without releasing female nuisance mosquitoes.
The male release strategies are an important “right-now” fix, but they’ll require an annual, costly release because male mosquitoes—with either MosquitoMate’s Wolbachia or Oxitec’s self-limiting gene—cannot pass on to the next generation their crucial trait. When these males are not being released, fertile wild males will mate with females and the population will rebound.
Eliminate Dengue’s female release strategy is sustainable long term, but it takes extensive monitoring to ensure the initial establishment of mosquitoes. While MosquitoMate and Oxitec do not disclose their costs, Eliminate Dengue hopes to make their system affordable at a cost of approximately $1 per person.
Some members of the public have advocated against these kinds of mosquito release programs, particularly when the mosquitoes have been genetically modified, as with Oxitec’s transgenic insects. While the United States Department of Agriculture received 2,600 responses to the Oxitec plan, only one response was filed regarding MosquitoMate’s non-GMO strategy.
In the United States, mosquito control districts are taking a cautious approach. They’re first trying the two nonpermanent male strategies in small areas. The Florida Keys will be evaluating mosquitoes on their Stock Island release site for 12 weeks. We should know how effective male Wolbachia-infected mosquitoes are at reducing populations by late summer.
Michaela Schultz, Graduate Student in Biology, Boston University
This article was originally published on The Conversation. Read the original article.
Why do some folks use social media but don't engage?
Psychologist says people who never comment on social media share these 5 positive traits
For over 20 years, social media has developed into a staple in many people’s day-to-day lives. Whether it’s to keep in communication with friends and family, following the thoughts of celebrities, or watching cat videos while sipping your morning coffee, there seem to be two types of social media users: commenters and lurkers.
The term “lurker” sounds equally mysterious and insidious, with some social media users writing them off as non-participants at best or voyeurs at worst. However, mindfulness expert Lachlan Brown believes these non-commenters have some very psychologically positive and healthy traits. Let’s take a look at how each one of these traits could be beneficial and see how fruitful lurking might be even though it can drive content creators crazy.
1. Cautious about vulnerability
Consciously or not, making a post online or commenting on one puts you and your words out there. It’s a statement that everyone can see, even if it’s as simple as clicking “like.” Doing so opens yourself up to judgment, with all the good, bad, and potential misinterpretation that comes with it. Non-commenters would rather not open themselves up to that.
These silent users are connected to a concept of self-protection by simply not engaging. By just scrolling past posts or just reading/watching them without commentary, they’re preventing themselves from any downsides of sharing an opinion such as rejection, misunderstanding, or embarrassment. They also have more control on how much of themselves they’re willing to reveal to the general public, and tend to be more open face-to-face or during one-on-one/one-on-few private chats or DMs. This can be seen as a healthy boundary and prevents unnecessary exposure.
Considering many comment sections, especially involving political topics, are meant to stir negative emotional responses to increase engagement, being extra mindful about where, when, and what you comment might not be a bad idea. They might not even take the engagement bait at all. Or if they see a friend of theirs post something vulnerable, they feel more motivated to engage with them personally one-on-one rather than use social media to publicly check in on them.
2. Analytical and reflective mindset
How many times have you gone onto Reddit, YouTube, or any other site and just skimmed past comments that are just different versions of “yes, and,” “no, but,” or “yes, but”? Or the ever insightful, formerly popular comment “First!” in a thread? These silent browsers lean against adding to such noise unless they have some valid and thoughtful contribution (if they bother to comment period).
These non-posters are likely wired on reflective thinking rather than their initial intuition. Not to say that all those who comment aren’t thoughtful, but many tend to react quickly and comment based on their initial feelings rather than absorbing the information, thinking it over, researching or testing their belief, and then posting it. For "lurkers," it could by their very nature to just do all of that and not post it at all, or share their thoughts and findings privately with a friend. All in all, it’s a preference of substance over speed.
3. High sense of self-awareness
Carried over from the first two listed traits, these silent social media users incorporate their concern over their vulnerability and their reflective mindset into digital self-awareness. They know what triggers responses out of them and what causes them to engage in impulsive behavior. It could be that they have engaged with a troll in the past and felt foolish. Or that they just felt sad after a post or got into an unnecessary argument that impacted them offline. By knowing themselves and seeing what’s being discussed, they choose to weigh their words carefully or just not participate at all. It’s a form of self-preservation through restraint.
4. Prefer to observe rather than perform
Some folks treat social media as information, entertainment, or a mix of both, and commenting can feel like they’re yelling at the TV, clapping alone in a movie theater when the credits roll, or yelling “That’s not true!” to a news anchor that will never hear them. But contrary to that, social media is a place where those yells, claps, and accusations can be seen and get a response. By its design, social media is considered by experts and the media as performative, regardless of whether it is positive or negative. Taking all of the previously mentioned traits into account, one can see why they would prefer to “observe the play” rather than get up on the stage of Facebook or X.
On top of that, these non-commenters could be using social media differently than those who choose to fully engage with it. Using this type of navigation, there may be nothing for them to comment about. Some commenters are even vying for this for their mental health. There are articles about how to better curate your social media feeds and manipulate algorithms to create a better social media experience to avoid unnecessary conflict or mentally tiring debate.
If you go on a blocking spree on all of your accounts and just follow the posters that boost you, it could turn your social media into a nice part of your routine as you mainly engage with others face-to-face or privately. In terms of commenting, if your curated Instagram is just following cute dogs and all you have to offer for a comment is “cute dog,” you might just enjoy the picture and then move on with your day rather than join in the noise. These non-commenters aren’t in the show and they’re fine with it.
5. Less motivated by social validation
The last trait that Brown showcases is that social media users who browse without posting tend to be independent from external validation, at least online. Social media is built to grow through feedback loops such as awarding likes, shares, and reposts of your content along with notifications letting you know that a new person follows you or wants to connect. This can lead many people to connect their activity on social media with their sense of self worth, especially with adolescents who are still figuring out their place in the world and have still-developing brains.
Engaging in social media via likes, shares, comments, and posts rewards our brains by having them release dopamine, which makes us feel good and can easily become addictive. For whatever reason, non-commenters don’t rely on social media as a means to gauge their social capital or self worth. This doesn’t make them better than those who do. While some non-commenters could have healthier ways to boost their self worth or release dopamine into their systems, many get that validation from equally unhealthy sources offline. That said, many non-commenters’ silence could be a display of independence and self confidence.
Whether you frequently comment online or don’t, it’s good to understand why you do or don’t. Analyzing your habits can help you determine whether your online engagement is healthy, or needs to be tweaked. With that information, you can then create a healthy social media experience that works for you.