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 Cryo-electron microscopy achieves unprecedented resolution using new computational methods
24.03.2017 | DOE/Lawrence Berkeley National Laboratory

nachricht How cheetahs stay fit and healthy
24.03.2017 | Forschungsverbund Berlin e.V.

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Giant Magnetic Fields in the Universe

Astronomers from Bonn and Tautenburg in Thuringia (Germany) used the 100-m radio telescope at Effelsberg to observe several galaxy clusters. At the edges of these large accumulations of dark matter, stellar systems (galaxies), hot gas, and charged particles, they found magnetic fields that are exceptionally ordered over distances of many million light years. This makes them the most extended magnetic fields in the universe known so far.

The results will be published on March 22 in the journal „Astronomy & Astrophysics“.

Galaxy clusters are the largest gravitationally bound structures in the universe. With a typical extent of about 10 million light years, i.e. 100 times the...

Im Focus: Tracing down linear ubiquitination

Researchers at the Goethe University Frankfurt, together with partners from the University of Tübingen in Germany and Queen Mary University as well as Francis Crick Institute from London (UK) have developed a novel technology to decipher the secret ubiquitin code.

Ubiquitin is a small protein that can be linked to other cellular proteins, thereby controlling and modulating their functions. The attachment occurs in many...

Im Focus: Perovskite edges can be tuned for optoelectronic performance

Layered 2D material improves efficiency for solar cells and LEDs

In the eternal search for next generation high-efficiency solar cells and LEDs, scientists at Los Alamos National Laboratory and their partners are creating...

Im Focus: Polymer-coated silicon nanosheets as alternative to graphene: A perfect team for nanoelectronics

Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are less stable. Now researchers at the Technical University of Munich (TUM) have, for the first time ever, produced a composite material combining silicon nanosheets and a polymer that is both UV-resistant and easy to process. This brings the scientists a significant step closer to industrial applications like flexible displays and photosensors.

Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are...

Im Focus: Researchers Imitate Molecular Crowding in Cells

Enzymes behave differently in a test tube compared with the molecular scrum of a living cell. Chemists from the University of Basel have now been able to simulate these confined natural conditions in artificial vesicles for the first time. As reported in the academic journal Small, the results are offering better insight into the development of nanoreactors and artificial organelles.

Enzymes behave differently in a test tube compared with the molecular scrum of a living cell. Chemists from the University of Basel have now been able to...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

International Land Use Symposium ILUS 2017: Call for Abstracts and Registration open

20.03.2017 | Event News

CONNECT 2017: International congress on connective tissue

14.03.2017 | Event News

ICTM Conference: Turbine Construction between Big Data and Additive Manufacturing

07.03.2017 | Event News

 
Latest News

Argon is not the 'dope' for metallic hydrogen

24.03.2017 | Materials Sciences

Astronomers find unexpected, dust-obscured star formation in distant galaxy

24.03.2017 | Physics and Astronomy

Gravitational wave kicks monster black hole out of galactic core

24.03.2017 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>