Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

DDT-resistant insects given genetic boost that helps resistance spread

09.08.2005


Insects that can withstand the powerful pesticide DDT that was banned in the 1970s have a genetic advantage over their rivals that has helped them spread across the globe ever since, according to research published in Current Biology tomorrow (9 August 2005).



This discovery overturns current theories that resistance to pesticides burdens insects with a genetic disadvantage that would stop them from competing with non-resistant insects once farmers stop using that pesticide.

Instead, researchers now believe that fruit flies that develop resistance to DDT gain a two-fold advantage: not only can they survive being sprayed with pesticide, which other insects cannot, but in doing so they develop a genetic advantage that makes them and their offspring more likely to thrive even when spraying is abandoned.


Researchers warn that the same process may be going on when doctors across the world prescribe antibiotics to cure infections.

Antibiotic resistance may potentially confer the same kind of genetic advantage to ‘superbug’ bacteria, and measures such as preventing certain antibiotics from being prescribed may not halt the spread of antibiotic resistance in bacteria.

“We found that DDT resistance in fruit flies not only carries no cost but in fact confers an advantage when inherited through the female,” said Richard ffrench-Constant (correct), from the University of Bath, who led the study.

“This suggests that by becoming DDT resistant the female flies are passing on some unknown advantage to their progeny, presumably associated with the single metabolic enzyme (cytochrome P450) that they over express.’’

“These results are important for the use of any drug, pesticide or antibiotic as they suggest that resistance will not always go away when we do not spray or prescribe antibiotics.”

Scientists had previously believed that the genetic ‘cost’ of resistance would mean that DDT resistance would dwindle once the pesticide taken out of use and DDT-susceptible insects would regain dominance.

“Although this assumption is widespread, data to support this contention is actually thin,” said Professor ffrench-Constant. He believes previous work may not have looked at genetically related strains and that ‘costs’ may therefore be associated with the differing genetic backgrounds of insects examined, and not the resistance genes themselves.

“Experimenters looking at genetic fitness in resistant insects often only look at single character traits such as number of eggs laid, and often compare resistant and susceptible lines that are genetically unrelated.

“Differences in fitness therefore often correspond to differences in genetic background rather and are not due to the resistance gene itself.”

Using DDT-resistant fruit flies (Drosophila melanogaster) in state-of-the-art controlled temperature rooms provided by the Wolfson Trust, Caroline McCart, a PhD student in the Department of Biology and Biochemistry at the University, went to great lengths to make sure that DDT resistant and susceptible strains differed only by the resistance gene itself.

Using antibiotics they also ‘cured’ the flies of the microbes that are known to affect their ability to reproduce and could affect the results.

In order to assess the genetic fitness of both the resistant and susceptible strains, the researchers monitored the survival and development rate of all life stages of their offspring.

They found that DDT resistance in fruit flies not only carries no cost but in fact confers an advantage when inherited through the female.

This discovery comes at a time when a number of developing nations, including South Africa, are considering re-introducing (or continuing the use of) DDT in an attempt to reduce the major health problems caused by malaria.

Use of DDT (Dichloro-diphenyl-trichloroethane) increased enormously on a worldwide basis after World War II, primarily because of its effectiveness against the mosquito that spreads malaria and lice that carry typhus.

DDT-resistant mosquitoes were first detected in India in 1959, and they have increased so rapidly that when a local spray program is begun now, most mosquitoes become resistant in a matter of months rather than years.

Worryingly, some resistant strains also show ‘cross-resistance’ to a number of different compounds, so spraying with one insecticide can unexpectedly increase resistance to newer compounds subsequently introduced to try and overcome resistance.

The World Health Organization estimates that during the period of DDT use, approximately 25 million human lives have been saved. Today pyrethroids are most commonly used in mosquito control but they act on the same target in the nervous system as DDT and ironically spraying with DDT may therefore have pre-selected for resistance to the newer pyrethroids.

The University of Bath is one of the UK’s leading universities, with an international reputation for quality research and teaching. In 16 subject areas the University of Bath is rated in the top ten in the country.

Andrew McLaughlin | EurekAlert!
Further information:
http://www.bath.ac.uk/news/releases
http://www.bath.ac.uk

More articles from Life Sciences:

nachricht Symbiotic bacteria: from hitchhiker to beetle bodyguard
28.04.2017 | Johannes Gutenberg-Universität Mainz

nachricht Nose2Brain – Better Therapy for Multiple Sclerosis
28.04.2017 | Fraunhofer-Institut für Grenzflächen- und Bioverfahrenstechnik IGB

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Making lightweight construction suitable for series production

More and more automobile companies are focusing on body parts made of carbon fiber reinforced plastics (CFRP). However, manufacturing and repair costs must be further reduced in order to make CFRP more economical in use. Together with the Volkswagen AG and five other partners in the project HolQueSt 3D, the Laser Zentrum Hannover e.V. (LZH) has developed laser processes for the automatic trimming, drilling and repair of three-dimensional components.

Automated manufacturing processes are the basis for ultimately establishing the series production of CFRP components. In the project HolQueSt 3D, the LZH has...

Im Focus: Wonder material? Novel nanotube structure strengthens thin films for flexible electronics

Reflecting the structure of composites found in nature and the ancient world, researchers at the University of Illinois at Urbana-Champaign have synthesized thin carbon nanotube (CNT) textiles that exhibit both high electrical conductivity and a level of toughness that is about fifty times higher than copper films, currently used in electronics.

"The structural robustness of thin metal films has significant importance for the reliable operation of smart skin and flexible electronics including...

Im Focus: Deep inside Galaxy M87

The nearby, giant radio galaxy M87 hosts a supermassive black hole (BH) and is well-known for its bright jet dominating the spectrum over ten orders of magnitude in frequency. Due to its proximity, jet prominence, and the large black hole mass, M87 is the best laboratory for investigating the formation, acceleration, and collimation of relativistic jets. A research team led by Silke Britzen from the Max Planck Institute for Radio Astronomy in Bonn, Germany, has found strong indication for turbulent processes connecting the accretion disk and the jet of that galaxy providing insights into the longstanding problem of the origin of astrophysical jets.

Supermassive black holes form some of the most enigmatic phenomena in astrophysics. Their enormous energy output is supposed to be generated by the...

Im Focus: A Quantum Low Pass for Photons

Physicists in Garching observe novel quantum effect that limits the number of emitted photons.

The probability to find a certain number of photons inside a laser pulse usually corresponds to a classical distribution of independent events, the so-called...

Im Focus: Microprocessors based on a layer of just three atoms

Microprocessors based on atomically thin materials hold the promise of the evolution of traditional processors as well as new applications in the field of flexible electronics. Now, a TU Wien research team led by Thomas Müller has made a breakthrough in this field as part of an ongoing research project.

Two-dimensional materials, or 2D materials for short, are extremely versatile, although – or often more precisely because – they are made up of just one or a...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Fighting drug resistant tuberculosis – InfectoGnostics meets MYCO-NET² partners in Peru

28.04.2017 | Event News

Expert meeting “Health Business Connect” will connect international medical technology companies

20.04.2017 | Event News

Wenn der Computer das Gehirn austrickst

18.04.2017 | Event News

 
Latest News

Wireless power can drive tiny electronic devices in the GI tract

28.04.2017 | Medical Engineering

Ice cave in Transylvania yields window into region's past

28.04.2017 | Earth Sciences

Nose2Brain – Better Therapy for Multiple Sclerosis

28.04.2017 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>