Malaria is a major scourge on health in many parts of the world, particularly in Sub-Saharan Africa where over 90% of declared cases have been recorded. Mosquito nets impregnated with insecticides are considered as a good prevention and control weapon against the mosquito vectors, in particular in areas where malaria is strongly endemic.
The only insecticides currently recommended by WHO (1) are pyrethroids whose rapid action causes a “knock-down (KD)” (2) effect and high mortality when mosquitoes come into contact with it, at much smaller doses than those which are toxic for humans and other mammals. Resistance is, however, emerging among many vector species, including Anopheles gambiae in tropical Africa. IRD scientists from the research unit “Vector population characterization and control” therefore investigated a new strategy. This involves combining as a mixture, in the same mosquito net, two insecticides with distinct action mechanisms, a pyrethroid (bifenthrin) and a carbamate (carbosulfan) (3). The results of a recent trial conducted in the Bouaké region of the Ivory Coast show that use of doubly impregnated mosquito nets are effective in terms of mortality and blood-feeding inhibition among adult A. gambiae and Culex resistant to one or other of the insecticides. The positive interaction, or synergy, which sets in between the pyrethroid and the carbamate gives such combined impregnation a clear advantage. The process requires doses far below those usually applied in single impregnation. It consequently reduces the cost and toxicity of the treatment, thus ensuring the safety of users, especially of children.
The synergy between the pyrethroid and the carbamate underwent prior investigation in laboratory experiments on adult A. gambiae susceptible to these two classes of insecticide. The strongest synergy of action was observed in the proportion of 6.25 mg/m2 of carbamate (in other words 1/50th of the recommended dose) to 25 mg/m2 of pyrethroid (1/2 the recommended dose). That ratio was subsequently repeated in the Ivory Coast field trial. This mixture led to a mosquito mortality rate of 80%, about twice the expected rate assuming absence of any interaction between the two insecticides (41%). However, if the carbamate proportion was stepped up, there was a corresponding loss in the speed of action and the KD effect of the pyrethroid. This antagonism, strongest when the minimum effective dose of pyrethroid was combined with the maximum recommended dose of carbamate, was attributable to carbamate’s irritant and repellent action which keeps the mosquitoes away and precludes sufficiently long tarsal contact with the pyrethroid for it to work.
Marie Guillaume | alfa
Farming with forests
23.09.2016 | University of Illinois College of Agricultural, Consumer and Environmental Sciences (ACES)
Ecological intensification of agriculture
09.09.2016 | Julius-Maximilians-Universität Würzburg
The Fraunhofer Institute for Organic Electronics, Electron Beam and Plasma Technology FEP has been developing various applications for OLED microdisplays based on organic semiconductors. By integrating the capabilities of an image sensor directly into the microdisplay, eye movements can be recorded by the smart glasses and utilized for guidance and control functions, as one example. The new design will be debuted at Augmented World Expo Europe (AWE) in Berlin at Booth B25, October 18th – 19th.
“Augmented-reality” and “wearables” have become terms we encounter almost daily. Both can make daily life a little simpler and provide valuable assistance for...
With the help of artificial intelligence, chemists from the University of Basel in Switzerland have computed the characteristics of about two million crystals made up of four chemical elements. The researchers were able to identify 90 previously unknown thermodynamically stable crystals that can be regarded as new materials. They report on their findings in the scientific journal Physical Review Letters.
Elpasolite is a glassy, transparent, shiny and soft mineral with a cubic crystal structure. First discovered in El Paso County (Colorado, USA), it can also be...
For the first time, Fraunhofer IKTS shows additively manufactured hardmetal tools at WorldPM 2016 in Hamburg. Mechanical, chemical as well as a high heat resistance and extreme hardness are required from tools that are used in mechanical and automotive engineering or in plastics and building materials industry. Researchers at the Fraunhofer Institute for Ceramic Technologies and Systems IKTS in Dresden managed the production of complex hardmetal tools via 3D printing in a quality that are in no way inferior to conventionally produced high-performance tools.
Fraunhofer IKTS counts decades of proven expertise in the development of hardmetals. To date, reliable cutting, drilling, pressing and stamping tools made of...
At AKL’16, the International Laser Technology Congress held in May this year, interest in the topic of process control was greater than expected. Appropriately, the event was also used to launch the Industry Working Group for Process Control in Laser Material Processing. The group provides a forum for representatives from industry and research to initiate pre-competitive projects and discuss issues such as standards, potential cost savings and feasibility.
In the age of industry 4.0, laser technology is firmly established within manufacturing. A wide variety of laser techniques – from USP ablation and additive...
Every three years, the plastics industry gathers at K, the international trade fair for plastics and rubber in Düsseldorf. The Fraunhofer Institute for Laser Technology ILT will also be attending again and presenting many innovative technologies, such as for joining plastics and metals using ultrashort pulse lasers. From October 19 to 26, you can find the Fraunhofer ILT at the joint Fraunhofer booth SC01 in Hall 7.
K is the world’s largest trade fair for the plastics and rubber industry. As in previous years, the organizers are expecting 3,000 exhibitors and more than...
23.09.2016 | Event News
20.09.2016 | Event News
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26.09.2016 | Materials Sciences
26.09.2016 | Materials Sciences
26.09.2016 | Materials Sciences