Tag: Pesticide control

The slippery food slope.

The second in this three-part focus on food; both for us and our dogs!

A republication, within the terms of The Conversation site, of an article that was originally published on June 26th, 2018.

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Why it’s time to curb widespread use of neonicotinoid pesticides

By  Associate Professor of Entomology and Extension Specialist, Pennsylvania State University

Planting season for corn and soybeans across the U.S. corn belt is drawing to a close. As they plant, farmers are participating in what is likely to be one of the largest deployments of insecticides in United States history.

Almost every field corn seed planted this year in the United States – approximately 90 million acres’ worth – will be coated with neonicotinoid insecticides, the most widely used class of insecticides in the world. The same is true for seeds in about half of U.S. soybeans – roughly 45 million acres and nearly all cotton – about 14 million acres. In total, by my estimate, these insecticides will be used across at least 150 million acres of cropland, an area about the size the Texas.

Neonicotinoids are very good at killing insects. In many cases they require only parts per billion, equivalent to a few drops of insecticide in a swimming pool of water.

In recent years, concerns have been raised about the influence of neonicotinoids on bee populations. As an applied insect ecologist and extension specialist who works with farmers on pest control, I believe the focus on bees has obscured larger concerns. In my view, U.S. farmers are using these pesticides far more heavily than necessary, with potential negative impacts on ecosystems that are poorly understood.

Pesticides on seeds 

Most neonicotinoids in the United States are used to coat field crop seeds. Their role is to protect against a relatively small suite of secondary insect pests – that is, not the main pests that tend to cause yield loss. National companies or seed suppliers apply these coatings, so that when farmers buy seed, they just have to plant it.

The percentage of corn and soybean acreage planted with neonicotinoid seed coatings has increased dramatically since 2004. By 2011, over 90 percent of field corn and 40 percent of soybeans planted were treated with a neonicotinoid. Between 2011 and 2014, the area treated crept toward 100 percent for corn and 50 percent for soybeans. And the mass of neonicotinoids deployed in each crop doubled, indicating that seed suppliers applied about twice as much insecticide per seed. Unfortunately, many farmers are unaware of what is coated on their seeds, while others like the peace of mind that comes from an apparently better protected seed.

Unlike most insecticides, neonicotinoids are water soluble. This means that when a seedling grows from a treated seed, its roots can absorb some of the insecticide that coated the seed. This can protect the seedling for a limited time from insects. But only a small fraction of the insecticide applied to seeds is actually taken up by seedlings. For example, corn seedlings only take up about 2 percent, and it only persists in the plant for two to three weeks. The critical question is where the rest goes.

Clothianidin is a neonicotinoid used almost exclusively as a coating on seed corn. Maps from USGS.

Pervading the environment

Because neonicotinoids are water soluble, the leftover insecticide not taken up by plants can easily wash into nearby waterways. Neonicotinoids from seed coatings are now routinely found polluting streams and rivers around the country.

Here it is likely that they are poisoning and killing off some of the aquatic insects that are vital food sources for fishes, birds and other wildlife. In the Netherlands, neonicotinoids in surface waters have been associated with widespread declines in insectivorous bird populations – a sign that concentrations of these insecticides are having strong effects on food webs.

Neonicotinoids also can strongly influence pest and predator populations in crop fields. My lab’s research has revealed that use of coated seeds can indirectly reduce crop yield by poisoning insect predators that usually kill slugs, which are important crop pests in mid-Atlantic corn and soybeans fields.

More broadly, planting coated seeds generally decreases populations of insect predators in crop fields by 15 to 20 percent. These predatory insects can eat insect pests, such as black cutworm and armyworm, that can reduce yield. Crop fields with fewer resident predators are more vulnerable to pest infestations.

Slugs, shown here on a soybean plant, are unaffected by neonicotinoids, but can transmit the insecticides to beetles that are important slug predators. Nick Sloff/Penn State University, CC BY-ND

An exaggerated need

Neonicotinoid advocates point to reports – often funded by industry – which argue that these products provide value to field crop agriculture and farmers. However, these sources typically assume that insecticides of some type are needed on every acre of corn and soybeans. Therefore, their value calculations rest on comparing neonicotinoid seed coatings to the cost of other available insecticides.

History shows that this assumption is clearly faulty. In the decade before neonicotinoid seed coatings entered the market, only about 35 percent of U.S. corn acres and 5 percent of soybean acres were treated with insecticides. In other words, pest populations did not cause economically significant harm very often.

Importantly, the pest complex attacking corn today is more or less the same as it was in the 1990s. This suggests that it is not necessary to treat hundreds of millions of acres of crops with neonicotinoid seed coatings.

Neonicotinoids can harm birds via multiple pathways, sometimes in very small quantities.

From overkill to moderation

Should the United States follow the European Union’s lead and pass a broad ban on neonicotinoids? In my view, action this drastic is not necessary. Neonicotinoids provide good value in controlling critical pest species, particularly in vegetable and fruit production. However, their use on field crops needs to be reined in.

In the Canadian province of Ontario, growers can only use neonicotinoid seed treatments on 20 percent of their acres. This seems like a good start, but does not accommodate farmers’ needs very well.

Integrated Pest Management (IPM), a control strategy based on using pesticides only when they are economically justified, offers valuable guidelines. It was introduced in the late 1950s in response to issues stemming from overuse of insecticides, including environmental damage and pest populations that had evolved resistance. Field-crop growers have a good history of using IPM, but current use of neonicotinoids ignores pest risk and conflicts with this approach.

To implement IPM in field crops with neonicotinoids, seed companies need to acknowledge that the current approach is overkill and poses serious environmental hazards. Extension entomologists will then need to provide growers with unbiased information on strengths and limitations of neonicotinoids, and help farmers identify crop acres that will benefit from their use. Finally, the agricultural industry needs to eliminate practices that encourage unnecessary use of seed coatings, such as bundling together various seed-based pest management products, and provide more uncoated seeds in their catalogs.

These steps could end the ongoing escalation of neonicotinoid use and change the goal from “wherever possible” to “just enough.”

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It’s enough to make one give up!!

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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As with many of the other fine articles that appear on Mother Nature Network, this report by Russell McLendon has many links to other information sources, too many for me to set up. So if this report ‘speaks’ to you and you want to look up the background information then please go here and read it over on MNN.