Removing flowers helps reduce malaria transmission

Mosquitoes obtain most of their energy needs from plant sugars taken from the nectar of flowers. So, if these mosquitoes have found a suitable plant, they tend to stay in the vicinity of these plants. If those plants are located near human habitation, you know what will happen: mosquitoes will more easily bite humans and malaria can potentially be transmitted from mosquitoes to humans.

Thus, removing the flowers of an invasive tree from mosquito-prone areas might be a simple way to help reduce malaria transmission, according to a new study[1].

The study focused on the removal of the flowers of the invasive mesquite tree (Prosopis juliflora), that is native to Central and South America, but was introduced to new areas in the late 1970's and early 1980's as an attempt to reverse deforestation. The mesquite tree is a robust plant that grows rapidly and has become one of the worst invasive plants in many parts of the world. The shrub now occupies millions of hectares on the African continent, including countries such as Mali, Chad, Niger, Ethiopia, Sudan and Kenya. It tends to encroach on villages, bringing the mosquitoes ever closer and closer to humans.

Removing the flowers around some villages in Mali decreased the local mosquito vector population by nearly 60%.

Dr Gunter Muller, lead-author, said: "Mosquitoes obtain most of their energy needs from plant sugars taken from the nectar of flowers so we wanted to test the effect removing the flowers of the mesquite tree an invasive shrub would have on local mosquito vector populations. Our results show that the removal reduces total population levels of mosquitoes and reduces the number of older female mosquitoes in the population, which are known to transmit malaria parasites to humans. This suggests that removal of the flowers could be a new way to shift inherently high malaria transmission areas to low transmission areas, making elimination more feasible."

[1] Muller et al: The invasive shrub Prosopis juliflora enhances the malaria parasite transmission capacity of Anopheles mosquitoes: a habitat manipulation experiment in Malaria Journal - 2017