pesticides

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#New weapons on the way to battle wicked weedsa somber picture of the struggle against super-weeds emerged today as scientists described the relentless spread of herbicide-resistant menaces like pigweed

and horseweed that shrug off powerful herbicides and have forced farmers in some areas to return to the hand-held hoes that were a mainstay of weed control a century ago.

The reports on herbicide resistance and its challenges and how modern agriculture is coping were part of a symposium on the topic at the 246th National Meeting & Exposition of the American Chemical Society (ACS) the world's largest scientific society.

The problems associated with herbicide-resistant weeds are spreading and intensifying especially weed species resistant to multiple products including the mainstay of 21st century agriculture the herbicide glyphosate said Bryan Young Ph d. who spoke at the symposium.

He is with Southern Illinois University in Carbondale. More than 200 individual weed species have been confirmed resistant to at least a single herbicide with infestations covering millions of acres in the United states and 60 other countries.

It is spreading beyond soybeans and cotton. Weed management in corn has become more and more difficult in recent years due to herbicide-resistant weeds.

Farmers he pointed out are not battling the mild-mannered dandelion or snow thistle that home gardeners visualize at the mention of weed.

Young said that growers are responding to such challenges by integrating alternative herbicides into their weed control programs herbicides that work a different way

They also are turning to herbicides that have residual activity in the soil preventing weed seeds from growing into a new generation of weeds.

Herbicides however remain the most effective tools for managing weeds in terms of overall control and for cost efficiency Young emphasized.

They include new herbicide formulations that work in ways that sidestep the resistance mechanisms in today's weeds.

And they include crop seeds with genetic traits that enable farmers to apply herbicides to their fields without harming the crops.

We must remember that herbicides or herbicide-resistant crop traits don't create herbicide-resistant weeds Young said.

Rather the use and management of these technologies to gain control of weeds by practitioners determines the risk of herbicide-resistant weeds evolving.

We need to be better stewards of herbicides to reduce the impact of herbicide-resistant weed species. Story Source:

The above story is provided based on materials by American Chemical Society (ACS. Note: Materials may be edited for content and length h

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#Relationship between landscape simplification and insecticide use exploreda new UCSB study that analyzed U s. Department of agriculture (USDA) Census of Agriculture data spanning two decades (1987-2007) shows that the statistical magnitude existence

--and insecticide use varies enormously year to year. While there was a positive relationship in 2007--more simplified landscapes received more insecticides--it is absent

or reversed in all previous years. The findings were published in the Proceedings of the National Academy of Science (PNAS.

and insecticide use when examining 2007 data for seven midwestern states. Larsen's results also showed 2007 was increased positive with land area in cropland leading to increased cropland treated with insecticides.

But in 2002 and 1997 there was no statistically significant relationship; 1992 was increased negative cropland but decreased insecticides;

and 1987 was generally negative but sometimes null depending on the model specification used. According to Larsen the increase in agricultural production over the past four to five decades has corresponded to massive changes in land use often resulting in large scale monocultures separated by small fragments of natural land.

They just show that we don't really understand how either of those policies will affect insecticide use.

With just county-fixed effects the analysis showed a strong negative relationship between landscape simplification and insecticide use.

or land sharing in terms of insecticide use if the relationship between landscape simplification and insecticide use flip flops year to year concluded Larsen.

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Suppose a sustainability contract lists that the default should be integrated pest management rather than application of traditional pesticides Endres said.

if the farmer assumes the risk of IPM as opposed to traditional pesticide options there has to be some sort of up-front payment

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or larviciding by adding chemicals or biological larvicides to standing water to kill larvae. Currently the use of long-lasting insecticide treated bed nets and indoor residual spraying of homes are used widely for malaria transmission control

and are having a major impact on the burden of the disease. However this success is threatened now by factors such as a growing resistance to insecticides among mosquitoes.

Complementary methods of mosquito control such as LSM may become increasingly necessary in helping tackle the disease

Interventions included adding larvicide to abandoned mine pits streams irrigation ditches and rice paddies where mosquitoes breed

The tremendous progress made in malaria control in the last decade is threatened now by mosquito resistance to the insecticides available for long-lasting insecticide treated nets and indoor residual spraying.

in this case spraying swamps with larvicide using ground teams did not show any benefit. Current World health organization (WHO) guidelines on the use of LSM distinguish between urban

It will therefore be combined with insecticide-treated bed nets or indoor residual spraying to hammer down malaria across the tropics.

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and around plants can substantially reduce the need for chemical fertilizers pesticides and herbicides. The report How Microbes can Help Feed the World is based on the deliberation of a group of scientific experts who gathered for two days in WASHINGTON DC in December 2012 to consider a series of questions regarding how plant-microbe interactions

%while reducing fertilizer and pesticide requirements by 20%within 20 years according to the report. These estimates rest on the recognition that all plants rely on microbial partners to secure nutrients deter pathogens

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#Toxic nanoparticles might be entering human food supplyover the last few years the use of nanomaterials for water treatment food packaging pesticides cosmetics

For example farmers have used silver nanoparticles as a pesticide because of their capability to suppress the growth of harmful organisms.

First the scientists immersed the pears in a silver nanoparticle solution similar to pesticide application.

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#Insecticide-treated bed nets critical to global elimination of filariasisan international team of scientists have demonstrated that a simple low-cost intervention holds the potential to eradicate a debilitating tropical disease that threatens nearly 1. 4

The researchers including Case Western Reserve University School of medicine professor James Kazura MD found that insecticide-treated bed nets reduce transmission of lymphatic filariasis to undetectable levels--even

Our study quantifies the effect of the most widely implemented vector control measure--insecticide-treated bed nets

Insecticide-treated bed nets already are used widely in areas where lymphatic filariasis and malaria are present.

The insecticide reduces the life-span of the insect by half preventing it from living long enough for the parasite to become capable of transmission.

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#Do herbicides alter ecosystems around the world? Scant research makes it hard to provethe number of humans on the planet has doubled almost in the past 50 years

As a result the use of pesticides and their effect on humans animals and plants have become more important.

Many laboratory studies have shown that pesticides can harm organisms which they were meant not to affect.

Can the biochemical effects of pesticides upset entire ecosystems? Professor Heinz KÃ hler and Professor Rita Triebskorn from the University of TÃ bingen's Institute of Evolution and Ecology (Eve) have published a study on the link between pesticides and changing ecological systems

in the latest edition of Science. The two ecotoxicologists cite deficits in the research which have prevented recognition of the consequences of biochemical pesticide effects on a species population or on the composition of biological communities.

Although there are many indications of animal populations and ecosystems changing because of pesticides there are few studies proving the connection without a doubt KÃ hler

and Triebskorn say. The researchers point to mathematical and experimental approaches which can be used to recognize links between the effects of pesticides in individuals

and ecological changes in biological communities and ecosystems in regions where intensive farming is practiced. An important role is played by number of rare studies combining experimental fieldwork and research on sections of ecosystems as well as a broad selection of chemical and biological analyses.

KÃ hler and Triebskorn also postulate interdependent effects between pesticides and global warming. The researchers forecast changes to natural selection the spread of infections and the sexual development and fertility of wild animals.

The researchers say it is a further challenge for science to show how strongly the effects of pesticides are influenced by climate change

The links to the effect of pesticides at every level of increasing biological complexity require more thorough research say KÃ hler and Triebskorn.

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of agricultural pesticides. For bees in Northern europe poor weather conditions--combined with these various other factors

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--despite intensive and costly use of insecticides new University of Michigan-led study in northwest India concludes.

--despite heavy use of insecticides--is concentrated in the areas adjacent to the main irrigation canal that have experienced the most pronounced change in irrigation levels in the last decade.

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because typically insecticides work only during one or two of the life stages of these pests.

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#Early exposure to insecticides gives amphibians higher tolerance lateramphibians exposed to insecticides early in life--even those not yet hatched--have a higher tolerance to those same insecticides later in life according to a recent University of Pittsburgh study.

Published in Evolutionary Applications the Pitt study found that wood frog populations residing farther from agricultural fields are not very tolerant to a particular type of insecticide

This is the first study to show that tadpole tolerance to insecticides can be influenced by exposure to insecticides extremely early on in life--in this case as early as the embryonic stage said study principal investigator Rick Relyea Pitt professor of biological sciences within the Kenneth P

and pesticides and insecticides are hypothesized one cause said Jessica Hua lead author of the paper and a Phd candidate studying biological sciences in Relyea's laboratory.

--which also included Nathan Morehouse Pitt assistant professor of biological sciences--examined three potential factors that might allow larval wood frogs to have a high tolerance to the insecticide:

the concentration of the initial insecticide exposure the timing of the exposure and the population's history of exposure.

They chose to work with carbaryl a popular household insecticide that also is used for malaria prevention.

Both embryos and hatchlings from all four environs were exposed first to a low nonlethal concentration of the insecticide.

Later they exposed the same individuals to a lethal concentration of the insecticide at the tadpole stage

whether insecticide tolerance played a role in the frogs'acetylcholinesterase (ACHE) a key enzyme in the nervous system of animals.

The Pitt team measured the concentration of total tadpole ACHE in a sample of tadpole bodies finding that low exposure levels of carbaryl stimulated the tadpoles to produce greater amounts of the enzyme--making them more tolerant to the insecticide later in life.

whether exposure to an insecticide early in life can make amphibians more tolerant to other insecticides.

if a tolerance to one insecticide can convey cross tolerance to other insecticides that affect the nervous system similarly said Hua.

The paper Pesticide Tolerance in Amphibians: Induced Tolerance in Susceptible Populations Constitutive Tolerance in Tolerant Populations first appeared online in Evolutionary Applications.

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#Virus to control potato mothnew biological insecticides have emerged in recent years which make use of so-called entomopathogenic viruses that are harmful to insects in particular the baculovirus.

therefore relatively slow compared to chemical insecticides that have an immediate effect upon contact. Its use also requires expert knowledge and detailed monitoring of the moth's biological cycle ecology and behaviour

and is a worthwhile alternative to chemical insecticides which are still the primary method used by farmers in Ecuador.

Using biological pesticides that rapidly degrade in the environment would reduce the risks of pollution.

Need for an integrated control strategyfor efficient control of the Guatemalan potato moth the use of this viral pesticide must therefore necessarily form part of an integrated control strategy.

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#Pesticides contaminate frogs from Californian national parkspesticides commonly used in California's Central Valley one of the world's most productive agricultural regions have been found in remote frog species miles from farmland.

supporting past research on the potential transport of pesticides by the elements. California's Central Valley is one of the most intensely farmed regions in North america producing 8%of U s agricultural output by value.

While the use of pesticides such as triazines endosulfan and organophosphates is common across the U s. California uses more pesticides than any other state.

Our results show that current-use pesticides particularly fungicides are accumulating in the bodies of Pacific chorus frogs in the Sierra nevada said Kelly Smalling a research hydrologist from the U s. Geological Survey.

This is the first time we've detected many of these compounds including fungicides in these remote locations.

As with other amphibians agrochemicals potentially pose a threat to chorus frogs as exposure to pesticides can decrease their immune system thereby increasing the risk of disease.

The samples were tested for 98 types of pesticides traces of which were found in frog tissues from all sites said Smalling.

We found that even frogs living in the most remote mountain locations were contaminated by agricultural pesticides transported long distances in dust and by rain.

Two fungicides commonly used in agriculture pyraclostrobin and tebuconazole and one herbicide simazine were the most frequently detected compounds

and this is the first time these compounds have ever been reported in wild frog tissue. Another commonly detected pesticide was DDE (Dichlorodiphenyldichloroethylene) a breakdown product of DDT

which was banned in the United states in 1972. The continued presence of a DDT byproduct reveals how long this banned chemical can impact biodiversity.

Very few studies have considered the environmental occurrence of pesticides particularly fungicides which can be transported beyond farmland concluded Smalling.

demonstrating the need to keep track of continual changes in pesticides use and to determine potential routes of exposure in the wild.

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#Common agricultural chemicals shown to impair honey bees healthcommercial honey bees used to pollinate crops are exposed to a wide variety of agricultural chemicals including common fungicides

The researchers fed the pesticide-laden pollen samples to healthy bees which were tested then for their ability to resist infection with Nosema ceranae--a parasite of adult honey bees that has been linked to a lethal phenomenon known as colony collapse disorder.

On average the pollen samples contained 9 different agricultural chemicals including fungicides insecticides herbicides and miticides.

Sublethal levels of multiple agricultural chemicals were present in every sample with one sample containing 21 different pesticides.

Pesticides found most frequently in the bees'pollen were the fungicide chlorothalonil used on apples

and other crops and the insecticide fluvalinate used by beekeepers to control Varroa mites common honey bee pests.

But the study's finding that common fungicides can be harmful at real world dosages is new

We don't think of fungicides as having a negative effect on bees because they're not designed to kill insects vanengelsdorp said.

Federal regulations restrict the use of insecticides while pollinating insects are said foraging he but there are no such restrictions on fungicides

so you'll often see fungicide applications going on while bees are foraging on the crop.

This finding suggests that we have to reconsider that policy. In an unexpected finding most of the crops that the bees were pollinating appeared to provide their hives with little nourishment.

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and used as an organic pesticide could be a safe inexpensive treatment for parasitic worms in humans

which is applied to crops as a natural insecticide on some organic farms and Cryb proteins have been engineered into food crops such as corn

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In addition butterflies are also vulnerable to pesticides often used in intensively managed farming systems. Farmland is abandoned often for socioeconomic reasons.

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#Widely used pesticide toxic to honeybeesforthcoming research in the journal Environmental Toxicology and Chemistry analyzes the physiological effects of three separate pesticides on honey bees (Apis mellifera.

Deltamethrin fipronil and spinosad widely used pesticides in agriculture and home pest control were applied to healthy honeybees and proved toxic to some degree irrespective of dosage.

At sublethal doses the pesticides modulated key enzymes that regulate physiological processes cognitive capacities and immune responses such as homing flight associative learning foraging behavior and brood development.

Sensitivity to these insecticides and foraging range (as far as 1. 5 to 3 km) make A. mellifera an optimal candidate for monitoring the environmental impacts of pesticides.

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and inorganic chemicals dyes and pesticides and they can also be used in large scale applications. The results were published in the Royal Society of Chemistry journal RSC Advances in September 2012.

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In the U s. weedy rice is combatted increasingly by growing herbicide resistant crop strains Olsen says.

In recent years more than a third of U s. rice fields have been planted with herbicide-resistant rice.

But that places huge pressure on the weeds to acquire herbicide resistance by hook or by crook.

The mechanism of herbicide resistance that is bred into the crop is pretty simple Olsen says.

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#RNA-interference pesticides will need special safety testingstandard toxicity testing is inadequate to assess the safety of a new technology with potential for creating pesticides

The authors of the article Jonathan G. Lundgren and Jian J. Duan of the USDA Agricultural research service argue that pesticides

The safety concern as with other types of genetic modification and with pesticides generally is that the artificial interfering RNAS will also harm desirable insects or other animals.

Lundgren and Duan suggest that researchers investigating the potential of interference RNA pesticides create types that are designed to be unlikely to affect non-target species. They also suggest a research program to evaluate how the chemicals move in real-life situations.

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#Second door discovered in war against mosquito-borne diseasesin the global war against disease-carrying mosquitoes scientists have believed long that a single molecular door was the key target for insecticide.

For many years pyrethroid insecticides have been deployed in developing countries to fend off diseases such as malaria dengue fever and more.

They're so effective that they are the only insecticides the World health organization uses with their mosquito nets they distribute around the globe.

Our discovery of a second receptor in the mosquitoes'sodium channel gives us a better understanding of how the insecticide works at a molecular level as well as could lead to ways to stem mosquitoes'resistance to pyrethroids.

At the molecular level resistance appears as mutations in the primary receptor in the sodium channel that allow mosquitoes to survive exposure to the insecticide.

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#Insecticide causes changes in honeybee genes, research findsnew research by academics at The University of Nottingham has shown that exposure to a neonicotinoid insecticide causes changes to the genes of the honeybee.

The study published in the online journal PLOS ONE supports the recent decision taken by the European commission to temporarily ban three neonicotinoids amid concerns that they could be linked to bee deaths.

and insecticides but this is the first comprehensive study to look at changes in the activity of honeybee genes linked to one of the recently banned neonicotinoids imidacloprid.

and increase the activity of genes involved in breaking down toxins most likely to cope with the insecticide.

This is a very significant piece of research which clearly shows clear changes in honeybee gene activity as a result of exposure to a pesticide

and prohibited the use of six neonicotinoid pesticides including imidacloprid on our own-brand fresh and frozen produce

and have welcomed the recent approach by the European commission to temporarily ban three neonicotinoid pesticides as this will allow for research into the impact on both pollinators and agricultural productivity.

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Physicians and scientists from the university and from the California Department of public health found no increase in specific diagnoses that are considered most likely to be associated with pesticide exposure including respiratory gastrointestinal skin eye and neurological conditions.

The study evaluated emergency room visits in Sacramento County hospitals on days that pesticides were sprayed as well as the three days following spraying.

During the time of the study ultra-low volume of pyrethrin insecticide was used for spraying;

It is the same pesticide used to treat head lice in children and to kill fleas and ticks in pets.

Exposure to the pesticide has been reported to pose risks to human health including skin and eye irritation respiratory and gastrointestinal disturbances lethargy fatigue and dizziness.

She said it would be worthwhile to reproduce the study for other pesticides and spraying techniques.

The article is titled Correlation between aerial insecticide spraying to interrupt West Nile virus transmission and emergency department visits in Sacramento County California.

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A previous study published last summer by the research team documented that rodenticides were being found in the tissues of the cat-sized weasel-like critters

This new study solidifies that link documenting that female fishers who live in areas with a higher number of marijuana sites had more exposure to rodenticides

or agricultural areas where rodenticides are used often legally. Illegal marijuana cultivation on public lands is widespread

and some growers apply large quantities of numerous pesticides to deter a wide range of animals and insects from encroaching on their crops.

While the exposure of wildlife to rodenticides and insecticides near agricultural fields is not uncommon the amount

According to co-author PSW wildlife biologist Dr. Kathryn Purcell exposure of wildlife to pesticides has been documented widely

In marijuana cultivation sites regulations regarding proper use of pesticides are ignored completely and multiple compounds are used to target any

either directly consuming flavored rodenticides or by consuming prey that had ingested recently the poisons exposure may also predispose animals to dying from other causes.

Fishers in the southern Sierra nevada are highly susceptible to pesticide exposure because unlike their larger bodied relatives in other parts of the country that eat larger prey their diet consists of small mammals birds carrion insects fungi and other plant material.

By increasing the number of animals that die from supposedly natural causes these pesticides may be tipping the balance of recovery for fishers says Dr. Craig Thompson a PSW wildlife ecologist and the study's lead author.

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