Invasive mosquito helps break the spread of a parasite
Jul21

Invasive mosquito helps break the spread of a parasite

Some species of mosquitoes spread dangerous human diseases. But mosquitoes have their own parasites, like the protozoan Ascogregarina barretti, which is related to the organisms that cause malaria and toxoplasmosis, and infects the native North American mosquito Aedes triseriatus. The invasive mosquito, Aedes japonicus, a recent arrival in North America, does not contract As. barretti. Will the presence of Ae. japonicus dilute the prevalence of the parasite in the native mosquito? Find out this August at Katie Westby’s talk during ESA’s 2016 Annual Meeting in Fort Lauderdale, Florida. COS 6-6 -Interactive effects of species invasion and habitat quality on parasite prevalence: Evidence of a dilution effect Monday, August 8, 2016: 3:20 PM, room 124/125, Ft Lauderdale Convention Center Katie M. Westby, Tyson Research Center, Washington University in St. Louis, Eureka, MO Browse more presentations about mosquito ecology at the 2016 Annual...

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It takes more than climate change to cause amphibian decline

This post contributed by Monica Kanojia, Administrative Assistant/Governance for ESA. Amphibians have been around for hundreds of millions of years. They have survived numerous extinction events and yet somehow, in the past two decades, their numbers have been in severe decline. The population changes have been linked to many factors, including climate change and disease, habitat destruction and water pollution. Studies indicate that amphibians are sensitive to all of the proposed variables—not just one root cause. A unique quality of amphibian biology is their transdermal water uptake ability. Transdermal uptake allows for nutrients to be delivered across the skin. For example, the skin of a frog allows for the direct exchange of oxygen, carbon dioxide and water from the environment. While in ideal situations this would be beneficial, it currently poses a threat to amphibian populations. Overexposure to any nutrient can be lethal to an organism. With increased rates of carbon dioxide in the atmosphere, heavily polluted water and loss of water, amphibians’ ability to survive is diminishing. A majority of amphibian species go through reproductive and developmental stages that require a body of water. The eggs of amphibians are not as resilient as reptile or bird eggs because they are jelly coated and unsuitable for development on land; therefore, amphibians must return to water to reproduce. Increased agricultural and industrial run off and poor waste management has led to a decline in the quality of water available for amphibians. The main types of chemical contaminants affecting amphibian environments are pesticides and herbicides, heavy metals, increasingly acidic water and nitrogen pollution. According to a study published in the journal Environmental Health Perspectives by Tyrone Hayes from the University of California, Berkeley and colleagues, pesticides commonly used in cornfields in the western United States have adverse affects on amphibian larval growth and development, immune system and the size prior to and after metamorphosis. High levels of pesticides enter streams and groundwater as water runs off of farms, ranches, golf courses and suburban areas. While organic and low-risk pesticide use is encouraged by the U.S. Environmental Protection Agency, it remains predominantly unregulated… That is, the EPA lists guidelines for how to safely use pesticides for commercial and agricultural needs, but it does not strictly regulate what can and cannot be used. Herbicides, on the other hand, are made to disrupt photosynthesis capabilities of plants and were thought to have little to no effect on fish and wildlife.  But, as Science Daily reported in 2008, studies have revealed otherwise. For example, atrazine—one of the most commonly used herbicides on golf courses, home lawns and soybean and corn crops—is responsible for lethal changes...

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Fungus has been invading carpenter ants for 48 million years

Scientists have found that the parasitic fungus Ophiocordyceps unilateralis has possibly been invading carpenter ants (Camponotus) for 48 million years. The parasite not only infects the ant, but it manipulates the ant’s behavior, influencing it to bite the underside of the leaf at the veins. Once the ant hits an optimal location, the fungus grows rapidly, killing the ant and preparing it to release a new spore.

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Incorporating science into home gardening

Blanketing a home garden in pesticides poses a clear risk to the humans and animals who dine on it. But when the garden is compared to a human immune system, another problem becomes apparent: Just like antibiotics, pesticides wipe out the “good bugs” with the bad. These helpful predators and parasitoids are called natural enemies and they help to naturally control pests like aphids and caterpillars. Certain plants attract natural enemies and/or deter pests all together and can be used in place of harmful chemicals.

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From the Community: forming a biodiversity body and taxing tomatoes

Representatives from around 90 countries approved the formation of the Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services, Nature and Scientific American collaborated on a survey to analyze the public’s interest in science and the history of the tomato’s taxonomy in the United States is reviewed. Here are some stories in ecology from the second week in June.

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Nutrient enrichment linked to diseases in humans and wildlife

Scientists have provided a rather grim prognosis for global health: the recent increase in nutrient enrichment due to human activities, such as nitrogen pollution through fossil fuel combustion, is likely contributing to several varieties of infectious diseases in humans and wildlife.

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The silent force in the food web

Addition of parasites (red spheres) visibly increases connectivity of species in this representation of an Arctic food web. Studies of food webs fascinate community ecologists. There seems to be a never-ending supply of interactions to observe, analyze and use in predictions. From the largest apex predators, feeding once a week, to the smallest alga, constantly converting sunlight to energy, there’s a kind of wonder in the idea that all living things are connected. In truth, however, ecologists are just beginning to realize that in this picturesque painting of a community in harmony, some less cuddly players are conspicuously absent: parasites. In the May issue of the Journal of Animal Ecology, Per-Arne Amundsen of the Norwegian College of Fishery Science and his colleagues wanted to know whether including parasites in a food web would significantly alter the connectivity of the web itself. The connectivity is the proportion of possible interactions among species that are actually realized in the food web.  These numbers are usually low, since the possible number of connections equals the square of the number of species – if there are 20 species in a community, there are 400 possible connections. The authors examined a lake community where the interactions among species are especially well known.  They then produced a different food web that included parasites living within organisms in the original food web, and compared the two.  As expected, the number of connections increased. Predators often acquire parasites by preying on infected organisms; the authors found that each of the parasite types they studied was ingested by one-third of the free-living organisms. It’s well-known that parasites are ubiquitous within the food web, but, as pointed out in a commentary in the same issue, ecologists are at the point where they’re still talking about including parasites in food webs, but most are not actually doing it. The commentary, by Andrew Beckerman and Owen Petchey of the University of Sheffield, UK, also notes that another emerging line of research will be the study parasites’ effects not only on their hapless hosts, but also on each other. Amundsen, P., Lafferty, K., Knudsen, R., Primicerio, R., Klemetsen, A., & Kuris, A. (2009). Food web topology and parasites in the pelagic zone of a subarctic lake Journal of Animal Ecology, 78 (3), 563-572 DOI: 10.1111/j.1365-2656.2008.01518.x Beckerman, A., & Petchey, O. (2009). Infectious food webs Journal of Animal Ecology, 78 (3), 493-496 DOI:...

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