Pollution: Damaging ecosystems


Public Release: 

Pollution in cities damaging insects and ecosystems

University of Sheffield

High levels of pollution found in many of the world’s major cities are having negative effects on plants and insects, according to new research from the University of Sheffield.

The study, published in Nature Communications, reveals that plants exposed to high levels of nitrogen dioxide (NO2) – similar to levels recorded in major urban centres – are able to better defend themselves against herbivorous insects.

Led by Dr Stuart Campbell from the University’s Department of Animal and Plant Sciences, the research has discovered that plants exposed to increased levels of pollution produce more defensive chemicals in their leaves.

Results from the study show that insects feeding on these leaves grew poorly, which suggests high levels of air pollution may be having cascading negative effects on communities of herbivorous creatures.

Dr Campbell, who is also part of the P3 Centre – a centre of excellence for translational plant science at the University of Sheffield, said: “Nitrogen dioxide is a pollutant that causes severe health problems in humans, but our research has found that it may also be having a significant impact on plants and insects.

“Insects are a crucial part of nature and the world we live in. Insects are critical to the healthy functioning of ecosystems.

“Many people may be aware that insect pollinators, such as the thousands of species of bees, along with flies, moths and butterflies, are crucial for food production – but they also ensure the long-term survival of wildflowers, shrubs and trees.”

Dr Campbell added: “Insects that feed on plants (herbivorous insects) help return plant nutrients to the soil, and are themselves food for wild birds, reptiles, mammals, and yet more insects. Insects are also immensely important for decomposing decaying organic matter and maintaining healthy soils. Scientists are warning about massive declines in insect numbers, which should be incredibly alarming to anyone who values the natural world and our sources of food.

“Nitrogen dioxide is a major component of smog and is an example of pollution caused from human activity, particularly our reliance on fossil fuels. Levels of this pollutant in the atmosphere remain particularly high in cities, and especially in the UK. Our research shows another example of the dangers of pollution to our environments and the reasons why we need to make a united effort to tackle it.”

The international team of scientists, which includes a researcher now based at the US Environmental Protection Agency, also looked at whether insects have an effect on the ability of plants to absorb NO2 from the environment.

Plants that had been fed on by insects absorbed much less NO2, according to the study. The authors believe this indicates that insects could be influencing the amount of pollution removed from the air by urban green spaces. Urban trees can absorb gaseous pollutants like NO2, but the effects appear to vary between species and locations, and this may be due in part to the actions of leaf-feeding insects. Dr Campbell emphasised, however, that the primary concern would be for the insects themselves, and that further research is needed: “Research suggests that urban vegetation plays a modest role in taking up NO2. More work is needed, because many factors may influence the effect of urban plants on air quality, including herbivory. Plant feeding insects, however, face a number of different human threats, potentially including air pollution.”

The study, Plant defences mediate interactions between herbivory and the direct foliar uptake of atmospheric reactive nitrogen, is published in the journal Nature Communications.

The University of Sheffield’s Department of Animal and Plant Sciences is a leading department for whole organism biology, with the UK’s highest concentration of animal and plant researchers.

It is among the top five animal and plant research centres in the country for research excellence, according to the last Research Excellence Framework in 2014.

Animal and plant scientists at Sheffield study in locations from the Polar Regions to the tropics, at scales from within cells up to entire ecosystems. Their research aims both to understand the fundamental processes that drive biological systems and to solve pressing environmental problems.


The P3 Centre (Plant Production and Protection) at the University of Sheffield aims to apply exemplary theoretical research to tackle real world problems surrounding food sustainability. Find out more about P3 and how to collaborate with its experts in plant and soil science by visiting: http://p3.sheffield.ac.uk/

For more information on studying at the University’s Department of Animal and Plant Sciences, visit: https://www.sheffield.ac.uk/aps/index

Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.

science daily

New tracking system could show—at last—how pesticides are harming bee colonies

Neonicotinoids, the world’s most commonly used insecticides, effectively thwart many crop pests but they also have insidious effects on vital pollinators: bees. At high doses, these neurotoxins—which wind up in the pollen and nectar the bees collect—harm their memory and ability to gather food. Now, using an innovative tracking technique, researchers have shown that neonicotinoids broadly reduce activity in bumble bee colonies, making bees less likely to care for their young, and making it hard for the colony to regulate nest temperature. The findings could help unravel a long-standing mystery: how the pesticides harm bee colonies.

For years, laboratory studies have shown the damage that neonicotinoids can inflict on individual bees. But it’s much harder to conclusively demonstrate how the pesticides damage entire colonies, which contain hundreds or even thousands of bees, all interacting as one complex “superorganism.” Part of the difficulty is the variability of conditions in nature, where weather, disease, the floral richness of the landscape, and other factors that influence colony health can interact and skew results in unknown ways.

To figure out how the pesticides were affecting colonies, James Crall, an animal behavior biologist at Harvard University, decided to examine the bees’ collective behavior after exposure to the chemicals. But doing so was far from simple. Past efforts to track bees involve dotting them with paint, taping the footage for short periods of time, and then carefully examining and annotating their actions. “It’s hard to track them even for a 5-minute video,” Crall says. “It’s unimaginable to do that for many days for multiple colonies.”

Crall and his team found a solution by turning to tracking software that he had written as a Ph.D. student studying insect flight biomechanics at Harvard. He and colleagues glued uniquely patterned 3-by-4-millimeter tags onto the backs of hundreds of bumble bees. Finally, by adapting robotic equipment from a fruit fly lab, they assembled a moveable platform with two high-resolution cameras. Those cameras can regularly spy on up to a dozen bumble bee colonies, picking up the movement of the tags, and passing them onto computers for analysis.

The group chose bumble bees because they are much easier to work with than the iconic honey bee for two reasons: Their colonies contain hundreds, rather than tens of thousands, of individuals; and they are relatively content to forage in a confined space, whereas honey bees want to fly free outdoors.

The team then gave nine colonies sugar syrup laced with six parts per billion of a common neonicotinoid called imidacloprid, allowing them to feed on it whenever they wanted. Over the 12-day experiment, the overall level of activity of the bees and their social interactions decreased. Whereas bees in control colonies spent about 25% of the night caring for the brood, for example, the pesticide-consuming bees spent less than 20%, the researchers report today in Science. The team discovered that the lethargy was, inexplicably, stronger at night. In a further experiment, Crall and his colleagues showed that imidacloprid can hinder the ability of colonies to regulate their temperature, which they normally do by flexing their muscles and fanning their wings.

It’s important that a hive stay at a constant temperature for the colony’s larvae to develop properly. “That brood is their future. If they don’t take care of them, then there’s a likelihood of an effect on the colony,” says Richard Gill, a bee ecologist at Imperial College London. More broadly, he says, it’s important that the many workers communicate and interact. “All the cogs need to be turning at the right time for the machine to be functioning well,” Gill says. It’s possible that the various pesticide-induced effects could stunt the growth of the colony.

Now that Crall has shown these effects, he plans to develop tools for tracking and manipulating temperature in colonies to learn more about how pesticides and temperature interact. Ultimately, he hopes, the system of automated video surveillance could be used to make pesticide testing faster, cheaper, and more sophisticated. Entomologist Reed Johnson of The Ohio State University in Wooster, who was not involved in the research, thinks that likely. “It’s the future of how we’re going to be looking at pesticide effects.”


The future for coastal farmers in Bangladesh


A recent study published in Nature Climate Change has suggested that the future global effects of climate change will impact the livelihoods of over 200,000 coastal farmers in Bangladesh as sea levels rise. Flooding of saltwater is already negatively impacting coastal residents in the country as soil conditions alter, causing farmers to either change from historic rice farming to aquaculture or to relocate further inland to avoid such salinity changes.

Members of the study, including researchers from Ohio State University and the International Food Policy Research Institute gathered socioeconomic, geographic, population and climate change data to create models to allow them to estimate population shifts in the future based on varying levels of water encroachment within coastal areas and the resulting rising of soil salinity.

It was estimated that farms will lose up to 21% of their crop revenue every year when faced with these salinity changes, which will result in a large drive for migration within the country. Over the next 120 years, communities in coastal areas which are currently home to 1.3 billion people globally will be overwhelmed with seawater. This will result in roughly 40% of Bangladesh’s agricultural land being at risk. It has already been noted that residents of such areas are experiencing more frequent flooding and as a result some have begun altering their livelihoods to alternate solutions and practices.

“Many farmers have already converted some of their operations to aquaculture, raising shrimp and fish that do well in brackish water,” said Joyce Chen of Ohio State University in ScienceDaily.


As soil contamination increases due to flooding of seawater, the share of agricultural revenue from seafood farming such as shrimp is predicted to increase by up to 60%. However, converting from rice farming to aquaculture isn’t a cheap or simple process, with many rural farming communities expected to be unable to make these changes on such a large-scale.

The idea of increased flooding in the future is worrying to many; however to those who already base their livelihoods on the availability of seawater or brackish water resources, they require it to sustain their businesses. This is a notable issue which will need to be addressed and incorporated into future policy making so to reduce potentially harmful impacts to either industry.

Interestingly, the study stated that internal migration is likely to increase by 23% due to the factors mentioned above, however, migration abroad is estimated to decrease by 66% as soil salinity levels increase. This is believed to be due to the aquaculture industry providing more desirable jobs for residents.

“My concern is that the most vulnerable people will be the least resilient in the face of climate change, because they have limited resources to adapt their farming practices or to move longer distances in search of other employment,” said Chen.

The study concluded in stating that regional, governmental and international policy makers should plan early for such population shifts due to climate change and that specific effects in one country will impact on all neighboring countries and other industries as ripple effects will be seen on both a national and international level.

If you would like to read further on this subject then please see the links below:



 NUS study explains how two predators can benefit from collaboration

The crab spider lives exclusively in the slender pitcher plant and ‘steals’ the host’s prey – this ‘pilfering’ benefits the plant when the prey is big

Article ID: 703763

Released: 11-Nov-2018 10:45 PM EST

Source Newsroom: National University of Singapore

  • Credit: Lam Weng Ngai, NUS Department of Biological Sciences

    Although the crab spider Thomisus nepenthiphilus ‘steals’ prey from its host, the slender pitcher plant Nepenthes gracilis, a study by ecologists from the National University of Singapore found that the net effect of this ‘burglary’ can still be beneficial to the pitcher plant as it gets the residual nutrients from the prey discarded by the crab spider.

  • Credit: National University of Singapore

    A study conducted by ecologists from the NUS Department of Biological Sciences showed that the crab spider Thomisus nepenthiphilus lives exclusively in the slender pitcher plant Nepenthes gracilis, and provides supplementary nutrients for its host. NUS doctoral student Mr Lam Weng Ngai is a key member of the research team.

Newswise — Two recent studies by ecologists from the National University of Singapore (NUS) have shed light on the relationship between the slender pitcher plant and its ‘tenant’, the crab spider Thomisus nepenthiphilus, providing insights to the little known foraging behaviours of the spider.

Thomisus nepenthiphilus is found only in the slender pitcher plant Nepenthes gracilis, which is native to Singapore and can also be found in Indonesia, Borneo, and Malaysia. Although the pitcher plant is a carnivore that traps and devours insects to supplement its nutrient requirements, the crab spider Thomisus nepenthiphilus is able to exploit the pitcher plant’s sweet-smelling nectar to catch its prey while at the same time, provide supplementary nutrients for its host.

“Our two studies provide important insights into the circumstances that favour cooperation over parasitism, and the results are pivotal in attaining a better understanding of these interactions,” said research supervisor Associate Professor Hugh Tan, who is from the Department of Biological Sciences at the NUS Faculty of Science.

The benefit of being ‘robbed’

In the first study, Assoc Prof Tan, together with doctoral student Mr Lam Weng Ngai and former undergraduate student Miss Robyn Lim, found that pitchers that are without any crab spider get more nutrients out of each prey, while those inhabited by ‘tenants’ trap more prey but get less nutrients from each prey.

Their laboratory experiments found that the crab spider ambushes flies that feed at the pitcher plant and sucks the body fluids of the insect prey. The crab spider subsequently drops the carcasses of the prey, which still contain some nutrients, into the fluids in the pitcher for it to digest. As such, although the crab spider ‘steals’ from the pitcher plant and gets the first taste of the prey, the net effect of this ‘burglary’ can still be beneficial to the pitcher plant as it gets the residual nutrients from the prey.

The findings suggest that when resources are scarce, this partnership between the crab spider and the pitcher plant is beneficial. However, when resources are abundant, this partnership is not favourable. The results of the study were published in the journal Oecologia on 14 August 2018.

“A trend that has been observed in recent mutualism research is that under more stressful conditions, the frequency and intensity of mutualism between the different organisms increases. Our findings support this observation. In other words, the age-old adage ‘a friend in need is a friend indeed’ is true not just for humans, but also for plants and animals,” said Assoc Prof Tan.

Big prey, big gains

Assoc Prof Tan and Mr Lam also conducted additional experiments in the natural habitat of the plants. Through field surveys, the researchers identified the species of prey that were found to be in greater numbers in pitchers that were inhabited by spiders, and those that were not.

Laboratory experiments were conducted to measure the nutrient contents of these prey species to estimate how much nutrients the pitchers would obtain if the prey had been trapped with, and without, the help of the crab spiders.

“Our results confirm the findings of our earlier study – the T. nepenthiphilus crab spider does indeed help the N. gracilis pitcher plant catch many different species of prey. More importantly, the net contribution of T. nepenthiphilus to N. gracilis’ nutrition appears to be proportional to the size of prey that T. nepenthiphilus catches,” explained Mr Lam.

He elaborated, “If the crab spider only catches small prey, such as mosquitoes or scuttle flies, the net benefit to the pitcher plant will be negative – it will be ‘stealing’ nutrients from the pitcher plant. However, when the crab spider catches large insects like cockroaches or large bugs, the pitcher plant will benefit, as the ’service charge’ paid to the crab spider becomes small compared to the total amount of nutrients gained through the interaction. As such, the residual nutrients that the pitcher plant receives from the carcasses discarded by the crab spider is a good trade-off.”

The results of this study were published in the Journal of Animal Ecology on 10 October 2018.

Theoretical model to be constructed

Based on the insights gained from these two studies, the research team is now constructing a theoretical model on mutualisms that involve the provision of nutrients by one species to another. Such a model will allow scientists to examine the factors that make mutualisms stable, and monitor how changes in the environment, such as global warming or habitat modification, will alter the ecological outcomes.

Genetic literacy project


You may not like GMOs, but our planet sure does.

By Elizabeth Hood, PhD

(Image credit: Getty Images)

First of all, for plants that have been changed through incorporation of new genes, I prefer the term Genetically Engineered, or GE, rather than GMO. Thus, I will use GE in this blog.

As a young newly married person not in the field of science, I began learning about organic gardening and farming practices and was impressed by the methods they supported that limited spraying chemicals on their crop or garden plants. I also bought books that described how to sow plants next to each other (companion planting) so that they could ward off pests.

In theory, this sounds great, however, in practice it is very difficult. It also works better in some locations than in others. For example, the south has much higher insect pressure and many “organic” solutions are not very helpful.

I also understood at an early age that many commodity crop plants no longer had resistance to diseases or insects, which were controlled with pesticides. Therefore, when I first heard about genetic engineering when visiting my eventual graduate school home, I was really excited about the possibility of being able to add specific characteristics to crop plants that would help them to resist insects, diseases and weeds. To me, this was the perfect solution to a crisis in farming that would be beneficial not only to farmers, but also to human health — fewer chemicals, better health.

The first GE plants had new characteristics that made them resistant to environmental conditions. One of the very first improved crops through genetic engineering saved the papaya industry in Hawaii.

Anyone who has ever been to Hawaii has been introduced to this wonderful, orange, creamy-fleshed fruit. However, if not for genetic engineering, this fruit would not be available. The trees were plagued by a virus disease called Papaya Ringspot Virus (PRSV). The virus was transferred from tree to tree by a small insect, so the practice was to spray the trees with insecticide to kill the insect. This practice was not very successful and most of the trees in an orchard became infected anyway. When a Hawaiian scientist put a gene from the virus into the papaya tree, the virus could no longer infect the trees, and the orchards no longer were dying, AND the tree-growers no longer had to spray with insecticides. In this case, the winners were the growers, the consumers, and the environment. This same technology can be used for ANY viral disease of plants.

Another example of how GE can help the environment (and farmers and consumers) is through control of insects.

Organic farmers use a bacterium to combat insects by sprinkling the bacterium on the leaves of their plants. Genetic Engineers took this a few steps further by taking the bacterium’s genes (called Bt genes) that kill insects and putting them directly into the plant. The bacterium has more than 50 genes that kill insects.

By learning which ones kill which insects, scientists can make the plant resistant to their most damaging predators. Bt genes in corn, cotton, soybeans and eggplant (as well as other traits) have removed 6 million tons of pesticides from the environment. The Bt eggplant, which was developed for Bangladesh, has replaced insect sprays that were done without farmer’s protection at least 3 times per week, causing human health problems as well as environmental problems.

Again, we are all winners — the farmers, the consumers and the environment.

Dr. Elizabeth Hood has studied plant biology for 37 years — with a focus on the production of enzymes — to bring to reality the ‘biomass to bioproducts’ industry through biotechnology. She has over 80 publications and patents and is an invited speaker globally. Dr. Hood received an MS in Botany from Oklahoma State University and her Ph.D. in Plant Biology from Washington University in St. Louis.

The Economist

How does your garden grow?Africa needs a green revolution

Governments can help, but need to get their policies right

GETAHUN SHUMULO is what the Ethiopian government calls a “model farmer”. In the past he would toss seeds at random over his fields near Butajira, in the arable south. These days, using a plastic bottle in which he has cut a small hole, he plants them in pencil-straight lines. To keep the soil healthy he rotates his crops each year. Thanks to hardier seeds from the local agricultural office he now grows mostly maize, Ethiopia’s cheapest staple. “If you do everything the government tells you, you can grow more of it every year,” he says. After feeding his family of nine, he sells more than half his produce.

Farmers like Getahun are sowing the seeds of transformation. The more they grow, the more money they have. The more they spend, the more jobs they help create in market towns and cities. Meanwhile, many rural people are giving up farming entirely and moving to the towns. On average, they work longer hours than they once did in the fields, and are more productive.

Something akin to Asia’s rural development may, at last, be happening in parts of Africa. Since 2002 the proportion of African workers employed in agriculture has fallen from 66% to 57%. Yet the real value of agricultural production has grown at an average pace of 4.6% a year, double the rate between 1970 and 2000. Even so, the region is lagging behind. Most of the increase comes from using more land, rather than improved productivity.

A green revolution—the increase in agricultural yields seen in most parts of the poor world apart from Africa since the 1960s—is unlikely to succeed if government is obstructive. “Government is the most important partner,” says Boaz Keizire of the Alliance for a Green Revolution in Africa, a think-tank with its headquarters in Kenya, “but in Africa it is the weakest link.”

Ideally, governments would pay for public goods, such as research and roads, and regulate markets lightly but fairly. Too often in Africa, they fail at these basic tasks. In Uganda, for instance, the market is so awash with understrength bags of fertiliser and feeble seeds that farmers are reluctant to invest in them. Many are also unable to get their crops to the market because of bad roads.

Earlier African regimes were even worse. After independence many squeezed farmers mercilessly, forcing them to sell their crops for a pittance through state-run marketing boards. (The aim was to provide cheap food for city dwellers—the result was to deter investment in farming and encourage smuggling.)

Then, in the 1980s, many African states liberalised trade, cut spending on agricultural research and subsidies, and hoped for the best. In 2003, with farm yields stagnating (see chart), the rhetoric shifted again. Governments pledged to allocate 10% of their budgets to agriculture. But by 2016 only ten countries were meeting that target, out of 44 with available data.

Malawi tops the public-spending charts, consistently allocating over 15% of its budget to agriculture. But much of that is swallowed up in a costly system of seed and fertiliser subsidies. The scheme has raised yields. It has also lined the pockets of the well-connected businessmen who win procurement contracts. It has had unintended consequences, too. Farmers who slap cheap fertiliser on their fields grow fewer nitrogen-fixing legumes, a cheap and green way of improving the soil.

Ethiopia, another big spender, offers a different approach. Farming output has grown by 6% a year since 2000, according to official figures, more than three times the rate in Malawi. Subsidies are relatively low. Instead, the government has pumped money into research, infrastructure and training. Its network of 72,000 “development agents”—experts sent to teach modern farming techniques—is Africa’s largest. They knock on Getahun’s door several times a month. “Sometimes they will even visit my fields when I’m not there,” he says approvingly. “They’ll ring me if they find something wrong.”

Reds in the seed beds

Why do approaches vary? Some researchers, such as Robert Bates and Steven Block of Harvard and Tufts universities, think that democracy improves policies by giving rural farmers more of a say. It does not always work out that way. In Malawi politicians use wasteful subsidies to win votes. By contrast, in authoritarian Ethiopia the government worked to avert the rural discontent that fed rebellions against its communist predecessors. It sees agricultural development as a way to build legitimacy.

Yet Ethiopia is not a model to emulate. In practice, its development agents “do everything” from tax collection to mobilising locals to attend meetings and vote for the ruling party, sighs an agricultural expert. They are part of an oppressive system of state control, which works well in some places while failing spectacularly in others. In recent years rural state structures have been among the first targets for violent unrest.

Elsewhere, poor governance has derailed policy altogether. In Uganda the state’s training services for farmers have crumbled, along with the waning popularity of Yoweri Museveni, the president. In a quest for votes the focus has shifted from training farmers to handing out inputs. Since 2014 distribution has been run by the army, creating jobs for veterans. “It’s a military operation,” says one of the officers in charge, “but with no bombs or bullets.” Farmers complain that seedlings arrive late or do not grow. Grace Apiyo, a 30-year-old farmer in the north, says she has never received any help or advice from the government. The value added by the average Ugandan farm worker has fallen by a quarter since 2002.

Political obstacles are not insuperable. On the whole, governance in Africa has improved. And better data can make governments more accountable, says Shenggen Fan, the head of the International Food Policy Research Institute, a think-tank in Washington. But it is hard to uproot “good practice” from one context and replant it in another. Agricultural policy, like farming itself, is a messy business. It needs the right soils and careful husbandry to thrive.

This article appeared in the Middle East and Africa section of the print edition under the headline “How does your garden grow?”

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About The Economist


Genetic literacy project

Viewpoint: Obstructionist governments have kept the ‘green revolution’ out of Africa

| November 7, 2018

A green revolution—the increase in agricultural yields seen in most parts of the poor world apart from Africa since the 1960s—is unlikely to succeed if government is obstructive. “Government is the most important partner,” says Boaz Keizire of the Alliance for a Green Revolution …. “but in Africa it is the weakest link.”

Ideally, governments would pay for public goods, such as research and roads, and regulate markets lightly but fairly. Too often in Africa, they fail at these basic tasks. In Uganda, for instance, the market is so awash with understrength bags of fertilizer and feeble seeds that farmers are reluctant to invest in them. Many are also unable to get their crops to the market because of bad roads.

Robert Bates and Steven Block of Harvard and Tufts universities think that democracy improves policies by giving rural farmers more of a say. It does not always work out that way. In Malawi politicians use wasteful subsidies to win votes. By contrast, in authoritarian Ethiopia the government worked to avert the rural discontent that fed rebellions against its communist predecessors ….

Yet Ethiopia is not a model to emulate …. its development agents “do everything” from tax collection to mobilizing locals to attend meetings and vote for the ruling party, sighs an agricultural expert. They are part of an oppressive system of state control ….

Read full, original article: Africa needs a green revolution