London School of Hygiene & Tropical Medicine Malaria Centre

New Mosquito Net technology to combat insecticide resistance


22 November 2016
A net that combines a novel insecticide (chlorfenapyr) with a pyrethroid marks a breakthrough in the development of long-lasting insecticidal nets to control resistant mosquitoes

A new net that can kill insecticide resistant mosquitoes which would normally survive exposure to standard pyrethroid treated nets is a significant development in long-lasting net (LLIN) technology. In experimental hut trials in Benin, led by Malaria Centre members from the London School of Hygiene & Tropical Medicine, the new net killed 70-80% of pyrethroid-resistant Anopheles gambiae whereas the standard pyrethroid LLIN killed only 20%. The new LLIN, now named Interceptor® G2, is co-formulated with the pyrrole insecticide, chlorfenapyr, and a pyrethroid and remained fully effective after 20 washes which is an important threshold to meet for WHO recommendation.

The field trial is the culmination of many years of partnership between The School, the chemical company BASF SE of Germany, and the IVCC to develop a new type of long lasting net to meet the future needs of malaria control. WHO estimates that over half the population of sub-Saharan Africa now sleeps under LLIN so it is important to preserve the effectiveness of this method of malaria prevention.

Few insecticides have the necessary attributes of high activity against mosquitoes, no cross resistance to pyrethroids, low solubility in water, and safe to use on nets. Chlorfenapyr is one of the few. However, it presented many puzzles during the research and development process. Because its mode of action is on cellular respiration and energy transfer, it is most toxic to anopheline mosquitoes when they are naturally active at night and trying find a blood meal. Hence its effectiveness on nets. This the first of several trials to be reported, and BASF will be submitting the Interceptor® G2 dossier to the WHO Pesticide Evaluation Scheme in 2017.

For a full report on the study, recently published in PLOS ONE, follow the link below to the article on The School's website: