Earth Wise

A look at our changing environment.

You are here: Home / Archives for parasites

parasites

An anti-malaria breakthrough

By Leave a Comment

The deadliest animal in the world is the mosquito.  Mosquitos infected 263 million people with malaria in 2023, leading to 600,000 deaths, 80% of which were children.  Malaria is caused by infection from Plasmodium parasites.  The parasites are transmitted to humans from the bite of infected female mosquitos.

Researchers at the University of California San Diego, Johns Hopkins University, UC Berkeley, and the University of Sāo Paulo have developed a new method that genetically blocks mosquitos from transmitting malaria.

The study was published in the journal Nature.  They used gene editing to change a single molecule within mosquitos.  The genetically altered mosquitos can still bite people with malaria and can still acquire parasites from their blood, but the parasites can no longer be spread to other people.  The switching of one specific amino acid known as L224 with a genetic alternative called Q224 prevents malarial parasites from reaching the salivary glands of the mosquito, thereby preventing the spread of infection.  In extensive tests, the researchers found that while the genetic switch disrupted the parasite’s infection capabilities, the mosquitos’ normal growth and reproduction remained unchanged.

The hope is that the replacement of a single amino acid in mosquitoes that prevents them from being infected with malarial parasites is a beneficial trait that can spread throughout a mosquito population.  The researchers believe that the trait can be spread across diverse mosquito species and populations and can pave the way for adaptable, real-world strategies to control malaria.

**********

Web Links

Stealth Genetic Switch in Mosquitoes Halts Malaria Spread

Photo, posted June 20, 2014, courtesy of John Tann via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

More trouble for bees

By Leave a Comment

Honeybees are a critical resource for American agriculture.  The western honeybee, Apis mellifera, pollinates more than 130 types of nuts, fruits, and vegetables, adding up to $15 billion worth of crops every year.  Honeybee health has been harmed by a combination of factors:  weather extremes, habitat loss, pesticides, and disease.  One of the biggest problems has been a parasite called varroa destructor, which is a Southeast Asian mite that first entered the United States in the 1980s.  The mites spread viruses to the bees.

The past year has been a particularly bad one for the bees.  Nearly 56% of managed honeybee colonies died off in the past year, the worst rate since annual reporting began in 2011. 

Even while American beekeepers seek solutions to the varroa problem, a potentially worse threat is on the horizon.  Another Southeast Asian mite, tropilaelaps, has been making its way across Asia and into Europe. If these mites arrive in North America, the results would be disastrous, wreaking havoc on honeybees and ravaging the nation’s food supply.

Western honeybees are the only honeybee species that is not native to Southeast Asia.  As the cradle of development of the bees, Southeast Asia has given rise to a bounty of parasites and viruses that are dependent upon them.  In turn, bees native to that region have had time to evolve defenses against these pathogens.  Western honeybees have not.

Beekeepers and authorities are taking measures to delay or prevent the arrival of tropilaelaps mites.  The stakes are very high.

**********

Web Links

After Devastating Winter Losses, Another Threat Looms for U.S. Beekeepers

Photo, posted April 14, 2013, courtesy of Paul Rollings via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Rats and climate change

By Leave a Comment

Human activity has made rats one of the most prolific mammals on the planet. Our waste, buildings, and ships provide food, shelter, and transport.  In the United States alone, rats cost the country approximately $27 billion each year in damage to infrastructure, crops, and contaminated food supplies. Additionally, rats carry and spread over 50 zoonotic pathogens and parasites, impacting public health around the world.

Now, climate change is adding to the problem. According to a new study recently published in the journal Science Advances, urban rat populations are exploding as global temperatures rise.  The researchers found that Washington DC, San Francisco, Toronto, New York City, and Amsterdam had the greatest population increases.  In fact, over the past decade, rats increased by a whopping 390% in Washington DC, 300% in San Francisco, 186% in Toronto, and 162% in New York City.  The study, which examined data from 16 cities globally, found that 11 of them showed significant increases in rat numbers.

Only Tokyo, Louisville, and New Orleans bucked the trend with declining rat numbers.

According to the researchers, the best pest management strategies involve making the urban environment less rat-friendly as opposed to removing rodents that are already there.  An example would be putting trash in containers instead of bags on the street. 

There aren’t many perks to the changing climate – unless, of course, you’re a rat. 

**********

Web Links

Increasing rat numbers in cities are linked to climate warming, urbanization, and human population

‘Perfect rat storm’: urban rodent numbers soar as the climate heats, study finds

Photo, posted September 25, 2018, courtesy of Tim Felce via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Pesticides and beeswax

By Leave a Comment

Honey bee colonies in the United States have experienced annual population declines since 2006.  Commercial beekeepers have reported honey bee colony loss rates averaging 30% each winter, which is startling when compared to historical loss rates of just 10-15%.  According to the USDA, there are many factors contributing to this decline, including parasites, pests, diseases, pesticides, and a phenomenon called Colony Collapse Disorder, in which worker bees abandon a hive and leave behind the queen.

According to a new study by researchers from Cornell University, beeswax in managed honey bee hives contains a variety of pesticide, herbicide, and fungicide residues.  Because bees reuse wax over years, these harmful chemicals can accumulate inside hives, exposing current and future generations of bees to long-term toxicity. 

The study, which was recently published in the Journal of Veterinary Diagnostic Investigation, adds that humans may also be exposed to these pesticides through contaminated honey, pollen, and beeswax (which is used in certain soaps, lotions, and cosmetics).  However, the amounts in these products are unlikely to pose a major threat to human health.

Pesticides get into the beeswax when bees feast on the nectar and pollen of plants that have been treated with the chemicals. According to the researchers, understanding which contaminants are impacting domestic honey bee populations could help better protect them and other pollinators, including birds, bats, wild bees, and other insects.

**********

Web Links

Pesticides detected in beeswax

Photo, posted November 22, 2008, courtesy of Andrew Rivett via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

A Vaccine For Bees | Earth Wise

By Leave a Comment

The US has seen annual reductions in honey bee colonies since 2006.  According to the USDA, there are many factors that have contributed to the decline.  These include parasites, pests, insecticides, disease, and a phenomenon called Colony Collapse Disorder in which worker bees abandon a hive and leave behind the queen.

One of major threats to bee colonies is American foulbrood disease, which is a bacterial condition that attacks bee larvae.  It is highly contagious and has no cure.  Until now, the only treatment method required burning the colony of infected bees along with the hives and equipment and treating nearby bee colonies with antibiotics.

Recently, the USDA has approved a conditional license for the world’s first vaccine for honey bees.  The vaccine contains inactive bacteria of the type that causes American foulbrood disease.

The vaccine is incorporated into the royal jelly fed by worker bees to the queen bee.  The queen ingests the feed and keeps some of vaccine in her ovaries.  This gives bee larvae immunity to the disease as they hatch and thereby reduces death from the illness.

According to the California State Beekeepers Association, the new vaccine could be a major breakthrough for protecting bees.  Preventing the infection in hives could avoid costly, destructive measures and allow the beekeepers to focus on other important elements of keeping bees healthy.

Bees as pollinators play a critical role in many ecosystems.  For humankind, pollinators such as bees, birds, and bats are responsible for about a third of the world’s crop production.

**********

Web Links

US approves world’s first vaccine for declining honey bees

Photo, posted June 6, 2022, courtesy of Bernd Thaller via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Examining The Decline Of Honey Bees | Earth Wise

By Leave a Comment

For many years, scientists have been sounding the alarm on the global struggle of pollinators.  Many of the invertebrate pollinator species, such as bees and butterflies, are facing extinction. And since 75% of the world’s food crops depend on pollination to some extent, the decline of pollinators poses a major threat to global food security.

Honey bees are among the struggling pollinators.  Over the past 14 years, bee colonies have been disappearing at an alarming rate in what is known as the “colony collapse disorder.” 

In an effort to understand why, scientists have often focused their research on environmental stressors, such as parasites, pesticides, and disease.  But according to new research by entomologists from the University of Maryland, honey bee life spans are simply 50% shorter today than they were 50 years ago.  In the study, which was recently published in the journal Scientific Reports, the researchers found that honey bees kept in a controlled, laboratory environment lived half as long as honey bees did in the 1970s.  This is the first study to show that genetics – as opposed to environmental stressors – may be influencing the broader trends seen in the beekeeping industry.

When the researchers modeled the effect of their findings on a beekeeping operation, they found that the resulting loss rates were about 33%.  This is similar to the average overwinter and annual loss rates reported by beekeepers during the past 14 years.

The next step is for researchers to compare trends in honey bee life spans across the U.S. and in other countries to see if there are differences in bee longevity. 

**********

Web Links

Honey Bee Lifespans are 50% Shorter Today Than They Were 50 Years Ago

Helping Agriculture’s Helpful Honey Bees

Photo, posted June 23, 2007, courtesy of Susan E. Ellis via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Could Lyme Disease Be Eradicated? | Earth Wise

By Leave a Comment

Tiny ticks are a big problem.  Measuring only three to five millimeters in size, ticks are widely distributed around the world.  They are external parasites, feasting on the blood of birds, reptiles, amphibians, and mammals – including humans.

According to estimates from the Centers for Disease Control and Prevention, ticks infect an estimated 476,000 people with Lyme disease in the United States every year.  Lyme disease is caused by a bacterium called Borrelia burgdorferi that lurks in wild mice. Ticks that feed on the mice become infected and can then in turn infect people and animals.   

The disease is not only a problem in the United States, but in other parts of North America, Europe and Asia as well.  It often causes a characteristic “bullseye” rash and flu-like symptoms. If left untreated, it can lead to serious long-term health problems.

Currently, lyme disease is treated using antibiotics.  But antibiotics kill a wide range of bacteria – including healthy gut bacteria – which can lead to additional health issues and more antibiotic resistance.

A recent discovery by researchers from Northeastern University in Boston could allow Lyme disease to be eradicated in the wild.  The researchers found that a compound called hygromycin A is deadly to the bacterium that causes Lyme disease but harmless to animals and has little effect on most other bacteria. 

The little-known antibiotic cleared Lyme disease infection in mice, both when administered via injection and when ingested using bait.  As a result, dropping feeding baits could eradicate Lyme disease from whole areas or even entire countries.  The first field trial will be next summer.

**********

Web Links

Drug treatment for Lyme disease could lead to its eradication

Photo, posted June 21, 2017, courtesy of NIAID via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

The United States And Ticks | Earth Wise

By Leave a Comment

Tiny ticks are a big problem.  Measuring only three to five millimeters in size, ticks are widely distributed around the world.  They are external parasites, feasting on the blood of birds, reptiles, amphibians, and mammals – including humans.

According to estimates from the Centers for Disease Control and Prevention, ticks infect more than 300,000 people with Lyme disease in the United States every year, and the numbers continue to rise.  Other common tick-borne diseases include anaplasmosis, babesiosis, Rocky Mountain Spotted Fever, and powassan encephalitis.

But while the prevalence of tick-borne illnesses has steadily increased in the United States over the past two decades, a new study on tick surveillance and control “has revealed an inconsistent and often under-supported patchwork of programs across the country.”

The study, by university researchers at the CDC’s five Vector-Borne Disease Regional Centers of Excellence, is the first-ever examination of tick management programs in the United States.  The researchers found clear gaps in our public health infrastructure. 

According to the study, which was recently published in the Journal of Medical Entomology, less than 50% of public health and vector-control agencies conduct tick surveillance.  Only 25% test ticks for disease-causing germs.  And only 12% conduct or support tick-control efforts.  Researchers also discovered that the capacity for public tick-control efforts is low, as is the capacity for information and data sharing between agencies on ticks.    

The findings highlight the degree to which tick surveillance and control is lagging in the United States.  According to the research team, greater support for tick-management programs is critical, and they hope their findings will serve as a baseline from which to measure future improvements.  

**********

Web Links

Tick surveillance and control lagging in US

Photo, posted May 4, 2009, courtesy of Jerry Kirkhart via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Bees And Plastic

By Leave a Comment

Wild bees in Argentina have recently been found to be constructing nests entirely made of flimsy plastic material left on farms and scientists don’t know why.

In 2017 and 2018, researchers at Argentina’s National Agricultural Technology Institute built wooden, artificial nests for wild bees.  These bee species burrow into nests to individually lay larvae rather than having a large hive with queens and workers.  The artificial nests provide hollow openings that bees generally fill with cut leaves, twigs, and mud.

Sixty-three wooden nests were constructed and three were found lined entirely with plastic.  The bees carefully cut bits of plastic in the shape and size of fingernails and arranged them in an overlapping pattern in their nests.  The plastic seems to have come from plastic bags or films, which have a similar texture to the leaves bees ordinarily use to line their nests.  And, in fact, leaves were readily available to the bees making use of plastic.

This is the first time that bees have been seen making nests entirely out of plastic, but for years scientists have known bees were incorporating plastic into their building materials.  Research is needed to determine the potential impact plastic might have on bees, but the nest building shows that bees are highly adaptive to changing environments.

Plastic often forms a threat to wildlife in the form of microplastics that can be consumed.  But there is no evidence that bees are consuming plastic.  Some researchers have speculated that the plastic in bees’ nests may form a barrier against common nest issues like mold and parasites.

At this point, it is not clear whether it is a good thing or a bad thing that some bees are choosing plastic over natural materials, but it is certainly interesting.

**********

Web Links

Wild bees are building their homes from plastic—and scientists aren’t sure why

Photo, posted December 12, 2014, courtesy of Judy Gallagher via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Heat-Resistant Corals

By Leave a Comment

All over the world, coral reefs are being wiped out by rising sea temperatures brought about by climate change.  When sea temperatures get too high, the symbiotic relationship between coral polyps and microscopic algae living within the coral breaks down and the coral either digests or expels the algae.   The result is coral bleaching which weakens, and if it persists, kills the coral.

[Read more…] about Heat-Resistant Corals

WAMC Northeast Public Radio

WAMC/Northeast Public Radio is a regional public radio network serving parts of seven northeastern states (more...)