Winners and losers in the cotton field
Indirect side-effects of the cultivation of genetically modified plants
Genetically modified Bt cotton plants contain a poison that protects them from their most significant enemies. As a result, these plants rely less on their own defence system. This benefits other pests, such as aphids. These insights stem from a study supported by the Swiss National Science Foundation (SNSF).
Only ten years ago, genetically modified cotton grew on 12% of all fields – today it is cultivated on over 80% of all cotton fields around the world. Bt cotton contains a gene of Bacillus thuringiensis, a species of soil bacteria. The plant uses it to produce a poison whose effects are fatal to the principal cotton pests – voracious caterpillars. However, certain types of bugs and other pests begin to spread across cotton fields instead, as is the case in China. The decline in the use of chemical pesticides may be partly responsible for this development, but it is probably not the only factor.
Spoiling their appetites
A team of researchers led by Jörg Romeis from the Agroscope Reckenholz-Tänikon Research Station has now identified a biological mechanism that offers an additional explanation for the increase in new pests in Bt cotton fields (*). Cotton plants have a sophisticated defence system. When caterpillars begin to nibble on them, they form defensive substances, so-called terpenoids. This spoils the appetite of not only the caterpillars, but of many other nibblers as well.
The experiments of Romeis and his colleagues have shown that the poison contained in the Bt cotton kills the caterpillars before they cause enough damage for the plant to activate its defence system. Aphids – which are not disturbed by the Bt toxin – were thus able to multiply more strongly on these plants than on conventional cotton plants that used terpenoids to fight the caterpillars.
Also helpful against bugs?
Cotton aphids generally do not cause severe agricultural damage because they succumb to their natural enemies out in the open. His results are therefore not relevant to farming, says Romeis. However, he has for the first time revealed an indirect effect of Bt cotton: the killing of the caterpillars also affects other plant-eating insects because the plants' defence system remains inactive. Romeis now wants to investigate whether this effect is relevant to aphids only or also to the bugs that are creating problems for cotton farmers in China and in other cotton-growing regions of the world.
(*) Steffen Hagenbucher, Felix Wäckers, Felix Wettstein, Dawn Olson, John Ruberson and Jörg Romeis (2013). Pest tradeoffs in technology: Reduced damage by caterpillars in Bt cotton benefits aphids. Proceedings of the Royal Society B online. doi: 10.1098/rspb.2013.0042
(PDF available from the SNSF; e-mail: email@example.com)
Dr. Jörg Romeis
Forschungsanstalt Agroscope Reckenholz-Tänikon ART
Phone: +41 44 377 72 99
Communication division | idw
The most recent press releases about innovation >>>
Die letzten 5 Focus-News des innovations-reports im Überblick:
The more objects we make "smart," from watches to entire buildings, the greater the need for these devices to store and retrieve massive amounts of data quickly without consuming too much power.
Millions of new memory cells could be part of a computer chip and provide that speed and energy savings, thanks to the discovery of a previously unobserved...
Personal patches could reduce energy waste in buildings, Rutgers-led study says
What if, instead of turning up the thermostat, you could warm up with high-tech, flexible patches sewn into your clothes - while significantly reducing your...
A widely used diabetes medication combined with an antihypertensive drug specifically inhibits tumor growth – this was discovered by researchers from the University of Basel’s Biozentrum two years ago. In a follow-up study, recently published in “Cell Reports”, the scientists report that this drug cocktail induces cancer cell death by switching off their energy supply.
The widely used anti-diabetes drug metformin not only reduces blood sugar but also has an anti-cancer effect. However, the metformin dose commonly used in the...
A research team from the University of Zurich has developed a new drone that can retract its propeller arms in flight and make itself small to fit through narrow gaps and holes. This is particularly useful when searching for victims of natural disasters.
Inspecting a damaged building after an earthquake or during a fire is exactly the kind of job that human rescuers would like drones to do for them. A flying...
Key advance for future topological transistors
Over the last decade, there has been much excitement about the discovery, recognised by the Nobel Prize in Physics only two years ago, that there are two types...