England :  Oxitec’s ground-breaking approach to pest control has again been demonstrated in a further trial carried out by Moscamed inBrazil. In this trial Moscamed achieved a 96% suppression of the dengue mosquito in the village of Mandacaru, Bahia state,Brazil.

Scientists from Oxitec together with Moscamed and the University of Sao Paulo, Oxitec’s partners in Brazil, are collaborating to carry out field demonstrations of Oxitec’s technology against the dengue mosquito, Aedes aegypti. In Mandacaru, a village near the city of Juazeiro, releases of the genetically engineered ‘sterile’ OX513A mosquitoes resulted in a 96% reduction of the wild mosquito population in the target area after only 6 months. This level of suppression was maintained for a further 7 months using continued releases, at reduced rates, to avoid re-infestation. Almost 3,000 people were protected from the dengue mosquito during this period.

These results follow a previous trial which demonstrated an 80% reduction of a mosquito population in Itaberaba, part of the city of Juazeiro, Brazil. Similar results were also achieved in the Cayman Islands in 2011. The latest evaluation in Mandacaru achieved even greater reduction because it was conducted in a more isolated area and therefore had less immigration of wild mosquitoes from un-treated areas.

“Today’s result shows that sustained releases of our OX513A mosquitos can be a highly effective tool in reducing populations of the dengue mosquito” said Oxitec’s Dr Luke Alphey. “In this trial we’ve seen that when releases are carried out in a relatively isolated area, our approach results in even greater population reduction than that which we have reported previously, as immigration from immediate neighbouring areas is reduced. This also indicates that in the right conditions, local elimination of a target pest species should be possible.”

Dr Alphey explained that the study was also able to show maintenance of control into the peak mosquito season through sustained low level releases. “It’s particularly pleasing that Moscamed demonstrated they were able to maintain control after the initial suppression period through smaller scale releases of our mosquitoes. The wet summer months are when we would normally expect mosquito populations to peak, but even with reduced releases in the treated areas we were barely seeing any wild mosquitoes. This indicates that the approach is not only effective at combating the threat posed by dengue mosquitoes through the peak wet season but also that this approach is sustainable over time.”

Moscamed director Dr Aldo Malavasi said that the Oxitec approach offered an important new tool in the fight against the dengue mosquito.

“Brazil has one of the highest incidences of dengue fever in the world” he said. “We are pioneering the development of this innovative approach because we desperately need new weapons to target the dengue mosquito, which is growing in number despite conventional efforts to control it. This evaluation was carried out following an extensive programme of community engagement, and local people are highly supportive of what we’re doing. They understand better than anyone the threat posed by dengue fever, so it’s tremendously exciting to see that this approach may offer real hope to them and to others living in the shadow of this disease.”