New cocktail tackles mosquitoes more efficiently and in a more environmentally friendly manner

Mosquitoes pass on all kinds of serious illnesses (such as Zika, Malaria and Dengue), so tackling these insects is high on the global agenda. Chemical pesticides are being used a lot at present. This is not only harmful to the environment, but also becoming decreasingly effective: insects are relatively quick to develop a resistance to the various products. This is also the case with Bti, the most common organic pesticide. Ever increasing doses of Bti are needed to kill off mosquitoes, meaning that this organic product is also starting to cause environmental damage.

Based on the knowledge that mosquitoes become stressed in the presence of aromas from their natural enemies, which in turn suppresses their immune systems, the doctorate student Lin Op de Beeck from the KU Leuven discovered that Bti can be made to work more efficiently by adding a synthetic variant of these aromas. Op de Beeck was also able to demonstrate that these aromas affect the immune system so significantly that any surviving mosquitoes will die more quickly. This means that parasites using the mosquito to spread further are not given the opportunity to complete their incubation period, reducing the risk of passing on the disease.

“We already knew that mosquitoes reacted stressfully to so-called predator aromas, aromas secreted by their natural enemies. It is this stress response that suppresses the mosquito's immune system,” says Op de Beeck. “Recently a synthetic copy was made of aromas produced by the water boatman, which feeds on mosquito larvae in the water. In our research we noticed that the mosquitoes also reacted stressfully to this synthetic variant, leaving them with diminished immunity. We developed a cocktail of aromas from predators and a low, non-deadly dose of Bti. With the extra stress caused by the predator aromas the low dose of Bti still had a significant effect and the cocktail caused a high death rate among the mosquitoes,” explained Lin Op de Beeck.

A further advantage of this combined strategy is that the predatory aromas from the water boatman are easy to copy synthetically, making production of the cocktail with Bti simple and relatively cheap. “This new cocktail offers plenty of potential for a more efficient and more sustainable method for fighting mosquitoes. The fact that we need less Bti means that the impact on the environment is reduced and the speed at which mosquitoes can become resistant is much slower,” concludes the researcher.

The research was carried out under laboratory conditions. In the next stage the cocktail will be tested in a more natural environment.