Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:


DDT-resistant insects given genetic boost that helps resistance spread


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:

More articles from Life Sciences:

nachricht Novel mechanisms of action discovered for the skin cancer medication Imiquimod
21.10.2016 | Technische Universität München

nachricht Second research flight into zero gravity
21.10.2016 | Universität Zürich

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: New 3-D wiring technique brings scalable quantum computers closer to reality

Researchers from the Institute for Quantum Computing (IQC) at the University of Waterloo led the development of a new extensible wiring technique capable of controlling superconducting quantum bits, representing a significant step towards to the realization of a scalable quantum computer.

"The quantum socket is a wiring method that uses three-dimensional wires based on spring-loaded pins to address individual qubits," said Jeremy Béjanin, a PhD...

Im Focus: Scientists develop a semiconductor nanocomposite material that moves in response to light

In a paper in Scientific Reports, a research team at Worcester Polytechnic Institute describes a novel light-activated phenomenon that could become the basis for applications as diverse as microscopic robotic grippers and more efficient solar cells.

A research team at Worcester Polytechnic Institute (WPI) has developed a revolutionary, light-activated semiconductor nanocomposite material that can be used...

Im Focus: Diamonds aren't forever: Sandia, Harvard team create first quantum computer bridge

By forcefully embedding two silicon atoms in a diamond matrix, Sandia researchers have demonstrated for the first time on a single chip all the components needed to create a quantum bridge to link quantum computers together.

"People have already built small quantum computers," says Sandia researcher Ryan Camacho. "Maybe the first useful one won't be a single giant quantum computer...

Im Focus: New Products - Highlights of COMPAMED 2016

COMPAMED has become the leading international marketplace for suppliers of medical manufacturing. The trade fair, which takes place every November and is co-located to MEDICA in Dusseldorf, has been steadily growing over the past years and shows that medical technology remains a rapidly growing market.

In 2016, the joint pavilion by the IVAM Microtechnology Network, the Product Market “High-tech for Medical Devices”, will be located in Hall 8a again and will...

Im Focus: Ultra-thin ferroelectric material for next-generation electronics

'Ferroelectric' materials can switch between different states of electrical polarization in response to an external electric field. This flexibility means they show promise for many applications, for example in electronic devices and computer memory. Current ferroelectric materials are highly valued for their thermal and chemical stability and rapid electro-mechanical responses, but creating a material that is scalable down to the tiny sizes needed for technologies like silicon-based semiconductors (Si-based CMOS) has proven challenging.

Now, Hiroshi Funakubo and co-workers at the Tokyo Institute of Technology, in collaboration with researchers across Japan, have conducted experiments to...

All Focus news of the innovation-report >>>



Event News

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

14.10.2016 | Event News

Agricultural Trade Developments and Potentials in Central Asia and the South Caucasus

14.10.2016 | Event News

World Health Summit – Day Three: A Call to Action

12.10.2016 | Event News

Latest News

Resolving the mystery of preeclampsia

21.10.2016 | Health and Medicine

Stanford researchers create new special-purpose computer that may someday save us billions

21.10.2016 | Information Technology

From ancient fossils to future cars

21.10.2016 | Materials Sciences

More VideoLinks >>>