Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Fewer aphids in organic crop fields

20.05.2011
Farmers who spray insecticides against aphids as a preventative measure only achieve a short-term effect with this method. In the long term, their fields will end up with even more aphids than untreated fields. This has been reported by researchers at the Biocenter of the University of Würzburg in the scientific journal PLoS One.

What's the status of the biodiversity in differently managed triticale fields? This is what the biologists at the Department of Animal Ecology & Tropical Biology wanted to find out. Triticale is a cross between wheat and rye. The cultivation of this crop is on the rise across the globe, because it delivers good yields even in poor soil conditions.

When comparing conventionally managed crop fields, which were either sprayed with insecticides or were left untreated, Jochen Krauss, Iris Gallenberger and Ingolf Steffan-Dewenter made a discovery, which should catch the attention of every farmer: "According to our results, the preventative application of insecticides against aphids does not produce any advantages even though it consumes a lot of time and money," Jochen Krauss sums up.

The scientists studied five triticale fields that were sprayed with insecticides against aphids, comparing them to ten other fields without any such treatment. "To be sure, the application of the insecticide led to a short-term decrease of the pest density," says Krauss. "After four week's time, however, significantly more aphids could be found in these fields than in insecticide-free fields. This also astonished the farmers who made their fields available for our study."

More aphids as a result of a decrease in natural enemies

The scientists offer two possible explanations for this phenomenon. One possibility is: The insecticides indiscriminately kill off beneficial animals that feed on the aphids, such as ladybugs or the larvae of lacewings and hoverflies. Because their enemies are missing, the aphids find it easier to return and proliferate than in insecticide-free fields.

Another possibility is an indirect effect: The insecticide just kills the aphids, after which their enemies leave the field for a lack of prey. Final result: In this scenario, the aphid population can also recover better after their return because the natural enemies are missing.

Greater biodiversity in organic crop fields

In conventional fields that have not been sprayed with insecticides, the pest control through natural enemies seems to work better – thanks to the higher biodiversity in these fields. The biodiversity is far greater still in fields under organic management, as reported in PLoS One by the Würzburg scientists.

The researchers found five times as many plant species and 20 times more types of pollinating insects in the 15 organic crop fields included in the study than they did in conventional fields. Furthermore, they detected three times as many natural enemies of aphids and five times fewer aphids in the organic fields than in the conventional fields.

"Decreased functional diversity and biological pest control in conventional compared to organic crop fields", Jochen Krauss, Iris Gallenberger und Ingolf Steffan-Dewenter, PloS One, 18 May 2011

Contact person

PD Dr. Jochen Krauss, Department of Animal Ecology & Tropical Biology at the University of Würzburg, T (0931) 31-82382, j.krauss@uni-wuerzburg.de

Robert Emmerich | idw
Further information:
http://dx.plos.org/10.1371/journal.pone.0019502
http://www.uni-wuerzburg.de

More articles from Agricultural and Forestry Science:

nachricht Plasma-zapping process could yield trans fat-free soybean oil product
02.12.2016 | Purdue University

nachricht New findings about the deformed wing virus, a major factor in honey bee colony mortality
11.11.2016 | Veterinärmedizinische Universität Wien

All articles from Agricultural and Forestry Science >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Significantly more productivity in USP lasers

In recent years, lasers with ultrashort pulses (USP) down to the femtosecond range have become established on an industrial scale. They could advance some applications with the much-lauded “cold ablation” – if that meant they would then achieve more throughput. A new generation of process engineering that will address this issue in particular will be discussed at the “4th UKP Workshop – Ultrafast Laser Technology” in April 2017.

Even back in the 1990s, scientists were comparing materials processing with nanosecond, picosecond and femtosesecond pulses. The result was surprising:...

Im Focus: Shape matters when light meets atom

Mapping the interaction of a single atom with a single photon may inform design of quantum devices

Have you ever wondered how you see the world? Vision is about photons of light, which are packets of energy, interacting with the atoms or molecules in what...

Im Focus: Novel silicon etching technique crafts 3-D gradient refractive index micro-optics

A multi-institutional research collaboration has created a novel approach for fabricating three-dimensional micro-optics through the shape-defined formation of porous silicon (PSi), with broad impacts in integrated optoelectronics, imaging, and photovoltaics.

Working with colleagues at Stanford and The Dow Chemical Company, researchers at the University of Illinois at Urbana-Champaign fabricated 3-D birefringent...

Im Focus: Quantum Particles Form Droplets

In experiments with magnetic atoms conducted at extremely low temperatures, scientists have demonstrated a unique phase of matter: The atoms form a new type of quantum liquid or quantum droplet state. These so called quantum droplets may preserve their form in absence of external confinement because of quantum effects. The joint team of experimental physicists from Innsbruck and theoretical physicists from Hannover report on their findings in the journal Physical Review X.

“Our Quantum droplets are in the gas phase but they still drop like a rock,” explains experimental physicist Francesca Ferlaino when talking about the...

Im Focus: MADMAX: Max Planck Institute for Physics takes up axion research

The Max Planck Institute for Physics (MPP) is opening up a new research field. A workshop from November 21 - 22, 2016 will mark the start of activities for an innovative axion experiment. Axions are still only purely hypothetical particles. Their detection could solve two fundamental problems in particle physics: What dark matter consists of and why it has not yet been possible to directly observe a CP violation for the strong interaction.

The “MADMAX” project is the MPP’s commitment to axion research. Axions are so far only a theoretical prediction and are difficult to detect: on the one hand,...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

ICTM Conference 2017: Production technology for turbomachine manufacturing of the future

16.11.2016 | Event News

Innovation Day Laser Technology – Laser Additive Manufacturing

01.11.2016 | Event News

#IC2S2: When Social Science meets Computer Science - GESIS will host the IC2S2 conference 2017

14.10.2016 | Event News

 
Latest News

Will Earth still exist 5 billion years from now?

08.12.2016 | Physics and Astronomy

Oxygen can wake up dormant bacteria for antibiotic attacks

08.12.2016 | Health and Medicine

Newly discovered bacteria-binding protein in the intestine

08.12.2016 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>