Category: Food

Feeding our furry friends.

An insight into the eating behaviours of cats and dogs.

As it happens, Jean and I are vegetarians; Jean going way back in years to when she first turned away from meat. Thus the only meat that we purchase is from Cartwrights’, a local butcher in Grants Pass, where we buy hearts and liver for the dogs. The cats are fed on dried cat biscuits and canned cat food.

All owners of cats and dogs know that they have very different eating habits, and behaviours.

So to put some flesh on the bone, so to speak, about the eating behaviours of cats and dogs I am going to republish a recent essay that appeared over on The Conversation. As always, it is republished within the terms of The Conversation.

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Why cats are fussy eaters but dogs will consume almost anything

by Hannah Rowland, Lecturer in Ecology and Evolution & Research Fellow at Zoological Society of London, University of Cambridge

November 13, 2015

Anyone who’s watched a cat throwing up after munching on grass knows that our feline friends aren’t natural plant eaters. So you might be surprised to discover that these carnivorous animals share some important genes that are more typically associated with herbivores. And this might help explain why cats aren’t always easy to please when it comes to food.

New research suggests that cats possess the genes that protect vegetarian animals from ingesting poisonous plants by giving them the ability to taste bitter. Animals use their sense of taste to detect whether a potential food is nutritious or harmful. A sweet taste signals the presence of sugars, an important source of energy. A bitter taste, on the other hand, evolved as a defence mechanism against harmful toxins commonly found in plants and unripe fruits.

Evolution has repeatedly tweaked animals’ taste buds to suit various dietary needs. Changes in an animal’s diet can eliminate the need to sense certain chemicals in food, and so receptor genes mutate, destroying their ability to make a working protein.

I can haz chlorophyll. Lisa Sympson/Wikimedia Commons, CC BY-SA
I can haz chlorophyll. Lisa Sympson/Wikimedia Commons, CC BY-SA

One example of this comes from strictly meat-eating cats, who can no longer taste sweetness. But if bitter detection evolved to warn of plant toxins, then it stands to reason that cats, which (usually) eschew plants, shouldn’t be able to taste bitter either. Humans and other vegetable-munching animals can taste bitter because we possess bitter taste receptor genes. If cats have lost the ability to taste bitterness, we should find that their receptor genes are riddled with mutations.

Geneticists at the Monell Chemical Senses Center in Philadelphia scoured the genome of cats and other carnivorous mammals like dogs, ferrets, and polar bears to see if our carnivorous cousins have bitter genes. They were surprised to find that cats have 12 different genes for bitter taste. Dogs, ferrets, and polar bears are equally well endowed. So, if meat eating animals are unlikely to encounter any bitter morsels, why do they boast genes for tasting bitterness?

Taste test

To find out, Peihua Jiang, a molecular biologist at Monell, put cat taste buds to the test. He inserted the cat taste receptor gene into human tissue cells in the lab. When combined, the cell and the gene act as a taste receptor that responds to chemicals dropped onto it.

Jiang discovered that the cat’s taste receptors responded to bitter chemicals found in toxic plants and to compounds that also activate human bitter receptors. The cat bitter taste receptor, known as Tas2r2, responded to the chemical denatonium benzoate, a bitter substance commonly smeared on the fingernails of nail-biting children.

So why have cats retained the ability to detect bitter tastes? Domestic cats owners know how unpredictable cats’ dietary choices can be. Some of the “presents” cats bring to their owners include frogs, toads, and other animals that can contain bitter and toxic compounds in their skin and bodies. Jiang’s results show that bitter receptors empower cats to detect these potential toxins, giving them the ability to reject noxious foods and avoid poisoning.

Hair of the dog. Michal Hrabovec/Flickr, CC BY-NC-SA
Hair of the dog. Michal Hrabovec/Flickr, CC BY-NC-SA

But how often do meat-loving cats actually get exposed to bitter and toxic compounds in their diet, compared with the plethora of plant toxins that their vegetarian counterparts have to contend with? Jiang suggests this is not enough to explain why cats have retained such an arsenal of receptors.

Instead, cat taste receptors may have evolved for reasons other than taste. In humans, bitter taste receptors are found not only in the mouth, but also in the heart and in the lungs, where they are thought to detect infections. It remains to be seen if feline bitter receptor genes also double-up as disease detectors.

The discovery of feline bitter receptors might explain why cats have got a reputation as picky eaters. But their unfussy canine counterparts have a similar number of bitter taste receptors – so why are cats so finicky? One answer might lie in how the cat receptors detect bitter-tasting compounds. Research published earlier this year by another team of researchers showed that some of the cat taste receptors are especially sensitive to bitter compounds, and even more sensitive to denatonium than the same receptor in humans.

Perhaps cats are also more sensitive to bitter chemicals than dogs, or they may detect a greater number of bitter compounds in their everyday diet. Food that tastes bland to us or to a dog could be an unpleasant gastronomic experience for cats. So rather than branding cats as picky, perhaps we should think of them as discerning feline foodies.

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Once again, I find it wonderful and incredible that there is so much knowledge and experience “out there” and how quickly a few clicks of a computer mouse can make it available to all of you wonderful readers!

And with that, it’s time to go off and feed the dogs. (Only showing off – Jean is the one who feeds both our dogs and our cats!)

Speaking of Jean – it’s her birthday today!

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Dog Food Product Alert

Please share.

Dear Fellow Dog Lover,

According to a notice posted at PetSmart retail stores, Hill’s Science Diet is in the process of conducting a voluntary market withdrawal of some of its canned dog food products for unspecified reasons.

To learn which products are affected, please visit the following link:

Hill’s Science Diet Dog Food Market Withdrawal

Please be sure to share the news of this alert with other pet owners.

Mike Sagman, Editor
The Dog Food Advisor

P.S. Not already on our dog food recall notification list yet? Sign up to get critical dog food recall alerts sent to you by email. There’s no cost for this service.

Food, agriculture, and our climate.

Locavore or vegetarian? What’s the best way to reduce climate impact of food?

With Thanksgiving Day just behind us and Christmas just around the corner, this is the season of feasting.

Just last Monday I published an essay written by George Monbiot, Pregnant Silence, that highlighted the impact on our climate of modern food production. Here are a couple of paragraphs from that essay:

Freshwater life is being wiped out across the world by farm manure. In England, as I reported last week, the system designed to protect us from the tide of crap has comprehensively broken down. Dead zones now extend from many coasts, as farm sewage erases ocean life across thousands of square kilometres.

Livestock farming causes around 14% of the world’s greenhouse gas emissions: slightly more than the output of the world’s cars, lorries, buses, trains, ships and planes. If you eat soya, your emissions per unit of protein are 20 times lower than eating pork or chicken, and 150 times lower than eating beef.

Thus it seemed both timely and appropriate to republish a further essay on the topic. This one published in The Conversation by Elliott Campbell, who is Associate Professor, Environmental Engineering, at the University of California.  It is republished here under the terms of essays published in The Conversation.

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Locavore or vegetarian? What’s the best way to reduce climate impact of food?

November 25, 2015

Elliott Campbell

This year’s Thanksgiving feast falls only a few days before the start of the global climate summit in Paris. Although the connections are not always obvious, the topic of food – and what you choose to eat – has a lot to do with climate change.

Our global agriculture system puts food on the table but it also puts greenhouse gases (GHG) in the air, which represent a huge portion of global emissions. GHG emissions come directly from farms such as methane from cows and nitrous oxide from fertilized fields, while other emissions come from the industries that support agriculture, such as fertilizer factories that consume fossil fuels.

Still other emissions come from natural lands, which have massive stocks of natural carbon stored in plants and soils. When natural lands are cleared to make room for more food production, the carbon in those natural pools is emitted to the atmosphere as carbon dioxide.

Adding all these emissions together makes agriculture responsible for between roughly one fifth and one third of all global anthropogenic, or man-made, greenhouse gas emissions.

How can these emissions be reduced? My own research through the University of California Global Food Initiative has focused on evaluating a wide range of factors from biofuels to local food systems.

Undoubtedly, broad emissions reductions must come from political action and industry commitments. Nevertheless, an enlightened consumer can also help achieve meaningful reductions in GHG emissions, particularly for the case of food. The trick is to understanding what food means for your personal carbon footprint and how to effectively shrink this footprint.

On par with electricity

Zooming in from the global picture on emissions to a single home reveals how important our personal food choices are for climate change. You can use carbon footprint calculators, such as the University of California CoolClimate Tool, to get an idea of how important food is in relation to choices we make about commuting, air travel, home energy use, and consumption of other goods and services.

For the average U.S. household, food consumption will be responsible for about the same GHG emissions as home electricity consumption for the average US household.

Measuring the greenhouse gas impact of different foods is complex but in general, it’s commonly agreed that plant-based diets have a lower carbon footprint. davidwoliver/flickr, CC BY-NC
Measuring the greenhouse gas impact of different foods is complex but in general, it’s commonly agreed that plant-based diets have a lower carbon footprint. davidwoliver/flickr, CC BY-NC

That’s a significant portion of an individual’s GHG footprint but it could be seen as a blessing in disguise. While you may be stuck with your home or your vehicle for some time and their associated GHG emissions, food is something we purchase with great frequency. And every trip to the grocery store or farmer’s market is another opportunity for an action that has a significant and lasting impact on our climate.

Making concrete decisions, though, is not always straight-forward. Many consumers are faced with a perplexing array of options from organic to conventional foods, supermarkets to farmers markets, and genetically modified organisms to more traditional varieties.

And in truth, the carbon footprint of many food options is disputed in the scientific literature. Despite the need for more research, there appears to be a very clear advantage for individuals to chose a more plant-based diet. A meat-intensive diet has more than twice the emissions of a vegan diet. Reducing the quantity of meat (particularly red meat) and dairy on the table can go a long way to reducing the carbon footprint of your food.

Food miles and water recycling

Local food systems are popularly thought to reduce GHG emissions through decreased food transport or food miles. But in many cases food miles turn out to be a meaningful but small piece of the overall GHG emissions from food.

For example, a broad analysis of the US food supply suggests that food miles may be responsible for less than 10% of the GHG emissions associated with food. This general trend suggests that where you get your food from is much less important than first-order issues, such as shifting to a more plant-based diet.

A little-appreciated way of reducing the carbon footprint of food is to recycle nearby water rather than pump it long distances. The Pajaro Valley Water Management Agency (PVWMA) Water Resources Center in California sanitizes wastewater for direct use or blending with ground (well) water. US Department of Agriculture, CC BY
A little-appreciated way of reducing the carbon footprint of food is to recycle nearby water rather than pump it long distances. The Pajaro Valley Water Management Agency (PVWMA) Water Resources Center in California sanitizes wastewater for direct use or blending with ground (well) water. US Department of Agriculture, CC BY

Where, then, does this leave a rapidly emerging local food movement?

For starters, there are some cases where food miles have greater importance. For example, food miles can play a big part in the carbon footprint of foods when airplanes or refrigeration are required during transport.

There is, however, untapped potential for locally produced food to deliver carbon savings around water and fertilizers.

When water is pumped long distances, it can add to food’s carbon footprint. Re-use of purified urban wastewater for irrigating crops represents one strategy for addressing this challenge but is only economically and environmentally feasible when food production is in close proximity to cities.

Using fossil fuels to produce fertilizers, such as ammonia, can also be a big piece of the carbon footprint of food. Nutrients in reclaimed wastewater and urban compost may provide a low-carbon alternative to fossil fuel-based fertilizers. But similar to water re-use, reusing nutrients is most easily done when there is a short distance between food production and consumption.

To be sure, buying local food doesn’t imply that food or nutrient recycling has happened. But developing local food systems could certainly be a first step towards exploring how to close the water and nutrient loop.

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I am sure many, as with me, tend not to follow through on all the links in an online essay. But there was one that really caught my eye. It was the CoolClimate Calculator on the Berkeley Edu website. It allows one to fill in a number of figures in terms of living, travel, food and more, and determine one’s total tons CO2/year emitted and how that compares with other people in your neighbourhood.  Unfortunately, it only calculates CO2/year for US locations. Does anyone know of similar calculators online in, say, the United Kingdom? Would love to know.

You couldn’t make it up!

However hard one tried to!

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In Chapter Eight, Behaviours and Relationships, I speak of how the development of humans has been, unsurprisingly, the result of our human behaviours. Adding that it is likely that our behaviours have been damaging, in varying degrees, to the survival of our species and countless others for a very long time. Continuing:

But 2,000 years ago, the global population of man was only 300 million persons[1]. It took 1,200 years for that global population to become 1 billion persons; in 1800. Now track the intervals as we come forward in time.

In 1927, just 127 years later, the two-billionth baby was born. In 1960, only 33 years on, came the birth of the three-billionth baby. Just 16 years later, in 1974, the four-billionth baby was born. In 1987, now only 13 years later, we have a population of five billion persons. Around October 1999, the sixth-billionth baby was born.
The growth rate of global population is slowing[2] but nevertheless it is trending to a billion additional persons every decade. In other words, a 100-million population growth every year, or about 270,000 more persons every single day.

Combine man’s behaviours rooted in times way back with this growth in population and we have the present situation. A totally unsustainable situation for one basic and fundamental reason. We all live on a finite planet.

[1] http://en.wikipedia.org/wiki/Population_growth
[2] According to UN’s 2010 revision to its population projections, world population will peak at 10.1bn in 2100 compared to 7bn in 2011. A 2014 paper by demographers from several universities and the United Nations Population Division forecast that the world’s population will reach about 10.9 billion in 2100 and continue growing thereafter. However, some experts dispute the UN’s forecast and have argued that birthrates will fall below replacement rate in the 2020s. According to these forecasters, population growth will be only sustained till the 2040s by rising longevity but will peak below 9bn by 2050.

A growth of about 270,000 more persons every single day!

I am sure that I am not alone in seeing this growth in our population as something that is both unsustainable and a critical component of long-term damage to our planet.

But George Monbiot in a recent essay, in true Monbiot style, highlights an aspect of our human population and the damage resulting that would have never previously occurred to me.

Read it and see if you don’t agree likewise. (Again, there are just too many links in George’s essay to reconstruct in this republishing and, as the other day, I have highlighted those phrases that are a link to other material in red. Go here if you wish to further investigate those links.)

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Pregnant Silence

19th November 2015

It’s about time we discussed the real population crisis.

By George Monbiot, published in the Guardian 18th November 2015

This column is about the population crisis. About the breeding that’s laying waste to the world’s living systems. But it’s probably not the population crisis you’re thinking of. This is about another one, that we seem to find almost impossible to discuss.

You’ll hear a lot about population in the next three weeks, as the Paris climate summit approaches. Across the airwaves and on the comment threads it will invariably be described as “the elephant in the room”. When people are not using their own words, it means they are not thinking their own thoughts. Ten thousand voices each ask why no one is talking about it. The growth in human numbers, they say, is our foremost environmental threat.

At their best, population campaigners seek to extend women’s reproductive choices. Some 225 million women have an unmet need for contraception. If this need were answered, the impact on population growth would be significant, though not decisive: the annual growth rate of 83 million would be reduced to 62m (1). But contraception is rarely limited only by the physical availability of contraceptives. In most cases, it’s about power: women are denied control of their wombs. The social transformations they need are wider and deeper than donations from the other side of the world are likely to achieve.

At their worst, they seek to shift the blame from their own environmental impacts. Perhaps it’s no coincidence that so many post-reproductive white men are obsessed with human population growth, as it’s about the only environmental problem of which they can wash their hands. Nor, I believe, is it a coincidence that of all such topics this is the least tractable. When there is almost nothing to be done, there is no requirement to act.

Such is the momentum behind population growth, an analysis in the Proceedings of the National Academy of Sciences discovered, that were every government to adopt the one-child policy China has just abandoned, there would still be as many people on Earth at the end of this century as there are today. If two billion people were wiped out by a catastrophe in mid-century, the planet would still hold a billion more by 2100 than it does now.

If we want to reduce our impacts this century, the paper concludes, it’s consumption we must address. Population growth is outpaced by the growth in our consumption of almost all resources. There is enough to meet everyone’s need, even in a world of 10 billion people. There is not enough to meet everyone’s greed, even in a world of 2 billion people.

So let’s turn to a population crisis over which we do have some influence. I’m talking about the growth in livestock numbers. Human numbers are rising at roughly 1.2% a year. Livestock numbers are rising at around 2.4% a year. By 2050, the world’s living systems will have to support about 120m tonnes of extra human, and 400m tonnes of extra farm animals(2).

Raising them already uses three quarters of the world’s agricultural land. One third of our cereal crops are used to feed them. This may rise to roughly half by 2050. More people will starve as a result, because the poor rely mainly on grain for their subsistence, and diverting it to livestock raises the price. Now the grain that farm animals eat is being supplemented by oil crops, particularly soya, for which the forests and savannahs of South America are being cleared at shocking rates.

This might seem counter-intuitive, but were we to eat soya, rather than meat, the clearance of natural vegetation required to supply us with the same amount of protein would decline by 94%. Producing protein from chickens requires three times as much land as protein from soybeans. Pork needs nine times, beef 32 times.

A recent paper in the journal Science of the Total Environment suggests that our consumption of meat is likely to be “the leading cause of modern species extinctions”. Not only is livestock farming the major reason for habitat destruction and the killing of predators, but its waste products are overwhelming the world’s capacity to absorb them. Factory farms in the US generate 13 times as much sewage as the human population. The dairy farms in Tulare county, California produce five times as much as New York City.

Freshwater life is being wiped out across the world by farm manure. In England, as I reported last week, the system designed to protect us from the tide of crap has comprehensively broken down. Dead zones now extend from many coasts, as farm sewage erases ocean life across thousands of square kilometres.

Livestock farming causes around 14% of the world’s greenhouse gas emissions: slightly more than the output of the world’s cars, lorries, buses, trains, ships and planes. If you eat soya, your emissions per unit of protein are 20 times lower than eating pork or chicken, and 150 times lower than eating beef.

So why is hardly anyone talking about the cow, pig, sheep and chicken in the room? Why are there no government campaigns to reduce the consumption of animal products, just as they sometimes discourage our excessive use of electricity? A survey by the Royal Institute of International Affairs found that people are not unwilling to change their diets, once they become aware of the problem, but that many have no idea that livestock farming damages the living world.

It’s not as if eating less meat and dairy will harm us. If we did as our doctors advise, our environmental impacts would decline in step with heart disease, strokes, diabetes and cancer. British people eat, on average, slightly more than their bodyweight in meat every year, while Americans consume another 50%: wildly more, in both cases, than is good for us or the rest of life on Earth.

But while plenty in the rich world are happy to discuss the dangers of brown people reproducing, the other population crisis scarcely crosses the threshold of perception. Livestock numbers present a direct moral challenge, as in this case we have agency. Hence the pregnant silence.

www.monbiot.com

Footnotes:

  1. While the number of unintended pregnancies would fall by 52m (or 70%), this does not mean that the number of babies would fall by the same amount. The Guttmacher/UNFPA report breaks down the outcome thus: “21 million fewer unplanned births; 24 million fewer abortions; six million fewer miscarriages; and 0.6 million fewer stillbirths.”
  2. Additional global meat consumption by this date is estimated to be roughly 200 million tonnes. Boned meat comprises roughly half the weight of a living animal. So total additional livestock biomass will be in the order of 400 million tonnes, or 400 billion kg. The average human weight is 52 kg and the anticipated rise in population by 2050 is 2.3 billion (the median estimate is 9.7 billion by that date). So the additional human weight is likely to be somewhere around 120 billion kg.

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Powerful reasons to turn vegetarian or vegan. And well done if you are already there. Well done, indeed!

Dog Treats Recall

Dear Fellow Dog Lover.

Because you signed up on our website and asked to be notified, I’m sending you this special recall alert.

On October 25, 2015, Salix Animal Health of Deerfield, Florida announced it is expanding the recall of its Good ‘n’ Fun Beefhide Chicken Sticks because the product has the potential to be contaminated with Salmonella.

Salmonella is a bacteria that can affect the health of both pets and humans.

To learn which products are affected, please visit the following link:

Good ‘n’ Fun Beefhide Chicken Sticks Dog Chews Recall Expands

Please be sure to share the news of this alert with other pet owners.

Mike Sagman, Editor
The Dog Food Advisor

P.S. Not already on our dog food recall notification list yet? Sign up to get critical dog food recall alerts sent to you by email. There’s no cost for this service.

Yet another dog food recall

Dear Fellow Dog Lover,

Because you signed up on our website and asked to be notified, I’m sending you this special recall alert.

On October 2, 2015, K-9 Kraving Dog Food of Baltimore, Maryland, announced the recall of its Chicken Patties dog food because the product has the potential to be contaminated with Salmonella and Listeria mitocytogenes.

Salmonella and Listeria are bacteria that can affect the health of both pets and humans.

To learn which products are affected, please visit the following link: K-9 Kraving Raw Dog Food Recall of October 2015

Please be sure to share the news of this alert with other pet owners.

Mike Sagman, Editor
The Dog Food Advisor

P.S. Not already on our dog food recall notification list yet? Sign up to get critical dog food recall alerts sent to you by email. There’s no cost for this service.

Dog Food Recall Alert

Yet another one!

Note: If readers find these food recall alerts a waste of time, then do let me know – I’m aware that for many there are already too many emails in the ‘in-box’.

Dear Fellow Dog Lover,

On September 30, 2015, Salix Animal Health of Deerfield, Florida announced the recall of one lot of its Good ‘n’ Fun Beefhide Chicken Sticks because the product has the potential to be contaminated with Salmonella.

Salmonella is a bacteria that can affect the health of both pets and humans.

To learn which products are affected, please visit the following link: Good ‘n’ Fun Beefhide Chicken Sticks Dog Chews Recall

Please be sure to share the news of this alert with other pet owners.

Mike Sagman, Editor
The Dog Food Advisor

If you click on that link above, you will see pictures of the packets and also read this:

What’s Being Recalled?

The recalled product is packaged in a 2.8 ounce bag stamped on the back side with:

Lot # AO15010
Expiration date of 03/2018
UPC code 0 91093 82247 1

No other product is affected at this time.

Where Was It Sold?

The recalled “Good ‘n’ Fun Beefhide Chicken Sticks” was distributed nationwide by Salix Animal Health at the following retail stores:

Dollar General Stores
Dollar Tree Stores

Dog Food Recall Alert

Reminds me of London buses: You wait for hours and then two arrive almost one behind the other!

(Previous alert was just two days ago.)

Dear Fellow Dog Lover,

Because you signed up on our website and asked to be notified, I’m sending you this special recall alert.

On September 23, 2015, The U.S. Food and Drug Administration announced the recall of certain lots of Dingo brand dog chews because the product has the potential to contain amantadine.

Amantadine is a human antiviral drug not approved for use in animal food.

To learn which products are affected, please visit the following link: Dingo Chip Twists Dog Chew Treats Recall of September 2015

Please be sure to share the news of this alert with other pet owners.

Mike Sagman, Editor
The Dog Food Advisor

P.S. Not already on our dog food recall notification list yet? Sign up to get critical dog food recall alerts sent to you by email. There’s no cost for this service.

Dog Food Recall Alert

Republished for the wider promotion of this alert.

Dear Fellow Dog Lover,

Because you signed up on our website and asked to be notified, I’m sending you this special recall alert.

On September 25, OC Raw Dog of Rancho Santa Margarita, CA, announced it is recalling its OC Raw Chicken, Fish and Produce Raw Frozen Canine Formulation because it has the potential to be contaminated with Salmonella.

To learn which products are affected, please visit the following link:

OC Raw Dog Food Recall of September 2015

Please be sure to share the news of this alert with other pet owners.

Mike Sagman, Editor
The Dog Food Advisor

P.S. Not already on our dog food recall notification list yet? Sign up to get critical dog food recall alerts sent to you by email. There’s no cost for this service.

For safer, cheaper pest control, just add ants!

A very interesting report that recently appeared on Mother Nature Network (MNN).

We live in Josephine County here in Southern Oregon. Our next door neighbours to the East are Jackson County. Josephine and Jackson Counties share one very noble attribute: each is only one of just nine GMO-free counties in the entire United States of America.  Plus, as evidenced at our local Grants Pass Farmers’ Market every Saturday, the growing of organic fruit and vegetables is widespread in our county.  We feel very happy to have ended up in this part of America.

All of which makes a logical introduction to a report that appeared on MNN on September, 1st.  It is republished below.

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For safer, cheaper pest control, just add ants

Ants offer a surprisingly effective alternative to synthetic pesticides on crops ranging from cashews to sugar cane, according to a new review of more than 70 scientific studies.

By: Russell McLendon, September 1, 2015, 9:30 a.m.

Weaver ants can not only protect tree crops from pests, but may also benefit the quality of produce. (Photo: Rushen/Flickr)
Weaver ants can not only protect tree crops from pests, but may also benefit the quality of produce. (Photo: Rushen/Flickr)

Sometimes ants are pests, marching through our kitchens on an industrious quest for crumbs. But when faced with more serious pests — namely those that destroy crops on which people’s livelihoods depend — we can also use ants to our advantage.

Published in the Journal of Applied Ecology, a new research review suggests ants can control agricultural pests as efficiently as synthetic pesticides, with the bonus of being more cost-effective and generally safer. And since many pesticides pose a danger to helpful wildlife like birds, bees and spiders — not to mention humans — ants might be a key ally in feeding the planet’s booming human population.

The review covers more than 70 scientific studies on dozens of pest species that plague nine crop varieties in Africa, Southeast Asia and Australia. Because ants are organized as “superorganisms” — meaning the colony itself is like an organism, with individual ants acting as “cells” that can move around independently — they are uniquely capable of hunting down pests and then overwhelming them.

“Ants are great hunters and they work cooperatively,” says author Joachim Offenberg, a biologist at Aarhus University in Denmark, in a press release about the research. “When an ant finds its prey, it uses pheromones to summon help from other ants in the nest. By working together, they can subdue even large pests.”

Most studies in the review focused on weaver ants, a tropical genus of tree-dwelling ants that weave ball-shaped nests using leaves and larval silk. Since they live in the canopy of their host trees, near the fruit and flowers that need protection, weaver ants have a natural tendency to control pest populations in orchards.

A colony of weaver ants in India works on converting leaves into a nest. (Photo: Raghu Mohan/Flickr)
A colony of weaver ants in India works on converting leaves into a nest. (Photo: Raghu Mohan/Flickr)

In one three-year study, Australian cashew growers recorded yields 49 percent higher in trees guarded by weaver ants versus trees treated with synthetic chemicals. But higher yields were only part of the prize: The farmers also got higher-quality cashews from the trees with ants, resulting in a 71 percent higher net income.

Similar results were reported in mango orchards. While mango trees with ants had roughly the same yields as those with synthetic chemicals, the ants were cheaper — and the trees they inhabited grew higher-quality fruit. That led to a 73 percent higher net income compared with pesticide-treated trees. Not all crops had such dramatic results, but studies on more than 50 pests showed that ants can protect crops including cocoa, citrus and palm oil at least as effectively as pesticides.

“Although these are rare cases where the ants were superior to chemicals, many studies show that ants are just as efficient as chemical controls,” Offenberg says. “And of course ant technology is much cheaper than chemical pest control.”

To recruit weaver ants in their orchards, farmers just collect nests from the wild, hang them in plastic bags from tree branches and feed them a sugar solution while they build new nests. Once the ants establish their colony, farmers can help them expand by connecting target trees with aerial walkways made from string or vines.

The ants are mostly self-sufficient from there, needing only some water during the dry season — provided via plastic bottles in the trees — and pruning of non-target trees that host different ant colonies to prevent fights. Farmers can also help their ants by avoiding broad-spectrum insecticide sprays, researchers say.

Ants protect mango trees about as effectively as pesticides, but at less cost, research suggests. (Photo: Shutterstock)

It’s worth noting that ants can also be detrimental to some plants, such as when they herd sap-feeding insects like aphids and leafhoppers. But if they still fend off fruit-ruining flies and beetles, their net impact may be positive nonetheless. Not only do weaver ants kill pest insects on their trees, but their presence alone is reportedly enough to scare away marauders as large as snakes and fruit bats. And research suggests their urine even contains important plant nutrients.

The use of ants for pest control isn’t new. As early as 300 B.C., Chinese farmers could buy weaver ants in markets to release in their citrus groves, a practice that has faded over time, especially after the advent of chemical pesticides. But it may be coming back, both because ants are cheaper than pesticides and because certified organic produce can fetch higher prices, due to concerns that broad-spectrum pesticides harm more than just pests. Aarhus University is studying the use of weaver ants as pest control in Benin and Tanzania, for example, where the insects could lead to increased export revenue of $120 million and $65 million, respectively.

“To kill the flies with pesticides, you have to make the mango so poisonous that it can kill the maggot,” Aarhus University biologist Mogens Gissel Nielsen told China’s Xinhua news agency in 2010. “But when it is too poisoned for the maggot to eat, it might not be good for us to eat either.”

While the research in Offenberg’s review focused largely on weaver ants, he points out they “share beneficial traits with almost 13,000 other ant species, and are unlikely to be unique in their properties as control agents.” Lots of ants nest in the ground, and while it may be a challenge to relocate them, they too have shown promise in protecting a variety of commercially important crops.

“Weaver ants need a canopy for their nests, so they are limited to plantations and forestry in the tropics,” Offenberg says. “But ground-living ants can be used in crops such as maize and sugar cane. European wood ants are renowned for controlling pests in forestry, and new projects are trying to use wood ants to control winter moths in apple orchards. Ants could even be used to fight plant pathogens because they produce antibiotics to combat diseases in their dense societies.”

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