Organic pesticides not always 'greener' choice, study finds

Jun 22, 2010

Consumers shouldn't assume that, because a product is organic, it's also environmentally friendly.

A new University of Guelph study reveals some organic pesticides can have a higher environmental impact than conventional pesticides because the organic product may require larger doses.

Environmental sciences professor Rebecca Hallett and PhD candidate Christine Bahlai compared the effectiveness and environmental impact of organic pesticides to those of conventional and novel reduced-risk synthetic products on soybean crops.

"The consumer demand for organic products is increasing partly because of a concern for the environment," said Hallett. "But it's too simplistic to say that because it's organic it's better for the environment. Organic growers are permitted to use pesticides that are of natural origin and in some cases these organic pesticides can have higher environmental impacts than synthetic pesticides often because they have to be used in large doses."

The study, which is published today in the journal , involved testing six pesticides and comparing their environmental impact and effectiveness in killing - the main pest of soybean crops across North America.

The two scientists examined four synthetic pesticides: two conventional products commonly used by soybean farmers and two new, reduced-risk pesticides. They also examined a mineral oil-based organic pesticide that smothers aphids and another product containing a fungus that infects and kills insects.

The researchers used the environmental impact quotient, a database indicating impact of active ingredients based on such factors as leaching rate into soil, runoff, toxicity from skin exposure, consumer risk, toxicity to birds and fish, and duration of the chemical in the soil and on the plant.

They also conducted field tests on how well each pesticide targeted aphids while leaving their predators -- ladybugs and flower bugs -- unharmed.

"We found the organic pesticide had the most impact on the environment because it works by smothering the aphids and therefore requires large amounts to be applied to the plants," said Hallett.

Compared to the synthetic pesticides, the mineral oil-based and fungal products were less effective, as they also killed ladybugs and flower bugs, which are important regulators of aphid population and growth.

These predator insects reduce environmental impact because they naturally protect the crop, reducing the amount of pesticides that are needed, she added.

"Ultimately, the organic products were much less effective than the novel and conventional pesticides at killing the aphids and they have a potentially higher environmental impact," she said. "In terms of making pest management decisions and trying to do what is best for the environment, it's important to look at every compound and make a selection based on the environmental impact quotient rather than if it's simply natural or synthetic. It's a simplification that just doesn't work when it comes to minimizing ."

Explore further: Stanford researchers rethink 'natural' habitat for wildlife

More information: The paper will be available here: dx.plos.org/10.1371/journal.pone.0011250

Provided by University of Guelph

3.7 /5 (3 votes)

Related Stories

Study: Pesticides found in wine

Apr 04, 2008

A European environmental group said pesticides used on grapes were found in 35 of the 40 bottles of wine they tested.

The future of organic ornamental plants

Dec 11, 2009

Whether plants are grown for food or ornamental use, conventional agricultural production methods have the same environmental impact. Pesticides, herbicides, and chemical fertilizers can find their way into ...

Pesticides need sunscreen to beat the heat

Dec 18, 2006

A pesticide with a new in-built sunscreen will help farmers beat the heat in crop protection. This means that the bug sprays last longer, as they are protected from the strong rays of sunshine, reports Chemistry & Industry, the ma ...

Getting plants to rid themselves of pesticide residues

Sep 09, 2009

Scientists in China are reporting the "intriguing" discovery that a natural plant hormone, applied to crops, can help plants eliminate residues of certain pesticides. The study is scheduled for the Sept. 23 ...

Glacial melting may release pollutants in the environment

Oct 21, 2009

Those pristine-looking Alpine glaciers now melting as global warming sets in may explain the mysterious increase in persistent organic pollutants in sediment from certain lakes since the 1990s, despite decreased ...

Recommended for you

Plants with dormant seeds give rise to more species

Apr 18, 2014

Seeds that sprout as soon as they're planted may be good news for a garden. But wild plants need to be more careful. In the wild, a plant whose seeds sprouted at the first warm spell or rainy day would risk disaster. More ...

Scientists tether lionfish to Cayman reefs

Apr 18, 2014

Research done by U.S. scientists in the Cayman Islands suggests that native predators can be trained to gobble up invasive lionfish that colonize regional reefs and voraciously prey on juvenile marine creatures.

User comments : 0

More news stories

Researchers successfully clone adult human stem cells

(Phys.org) —An international team of researchers, led by Robert Lanza, of Advanced Cell Technology, has announced that they have performed the first successful cloning of adult human skin cells into stem ...

Biologists help solve fungi mysteries

(Phys.org) —A new genetic analysis revealing the previously unknown biodiversity and distribution of thousands of fungi in North America might also reveal a previously underappreciated contributor to climate ...

NASA's space station Robonaut finally getting legs

Robonaut, the first out-of-this-world humanoid, is finally getting its space legs. For three years, Robonaut has had to manage from the waist up. This new pair of legs means the experimental robot—now stuck ...

Ex-Apple chief plans mobile phone for India

Former Apple chief executive John Sculley, whose marketing skills helped bring the personal computer to desktops worldwide, says he plans to launch a mobile phone in India to exploit its still largely untapped ...

Filipino tests negative for Middle East virus

A Filipino nurse who tested positive for the Middle East virus has been found free of infection in a subsequent examination after he returned home, Philippine health officials said Saturday.

Egypt archaeologists find ancient writer's tomb

Egypt's minister of antiquities says a team of Spanish archaeologists has discovered two tombs in the southern part of the country, one of them belonging to a writer and containing a trove of artifacts including reed pens ...

Airbnb rental site raises $450 mn

Online lodging listings website Airbnb inked a $450 million funding deal with investors led by TPG, a source close to the matter said Friday.