Removal of invasive shrub could be an easy way to help reduce malaria transmission

July 4, 2017
A picture of the shrub Prosopis juliflora. Credit: Muller et al., Malaria Journal, 2017'

Removing the flowers of an invasive shrub from mosquito-prone areas might be a simple way to help reduce malaria transmission, according to a new study published in the open access Malaria Journal. Removing the flowers from villages in Mali decreased the local mosquito vector population by nearly 60%.

The study, carried out in the Bandiagra District in Mali, is the first of its kind to trial a direct environmental manipulation as a way to control mosquito vector populations in areas at risk of .

Dr Gunter Muller, lead author of the study from Hebrew University Hadassah Medical School, said: "Mosquitos obtain most of their energy needs from plant sugars taken from the nectar of so we wanted to test the effect removing the flowers of the shrub Prosopis juliflora would have on local mosquito vector populations. Our results show that of this particular shrub reduces total levels of mosquitoes and reduces the number of older female mosquitoes in the population, which are known to transmit 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."

The study focused on the removal of the flowers of the invasive shrub Prosopis juliflora, which 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. Prosopis juliflora 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.

Light traps to catch mosquitoes were set up across nine villages in the Bandiagra District, six of which were home to flowering Prosopis juliflora and three that had no presence of the shrub. After a first round of analysis was conducted to assess mosquito populations, the researchers cut all the flowering branches from Prosopis juliflora in three of the six infested villages, before setting up light traps to determine the effect removal of the shrub had on mosquito vector populations.

Dr John Beier, co-author of the research from the University of Miami, said: "The presence or absence of Prosopis juliflora in villages has a significant influence on the size of the mosquito population in general, on their species composition, on the sugar feeding status and, the age structure of female populations. As well as offering a potentially environmentally reasonable and sustainable strategy in reducing the incidence of malaria, there are also other benefits to be gained from removal of these plants. For example, these plants are known to encroach on crop and pasture lands."

The researchers found that villages where they removed the flowers saw mosquito numbers collected in the traps fall from an average of 11 to 4.5 for females, and 6 to 0.7 for male mosquitoes. The total number of mosquitoes across these villages decreased by nearly 60% after removal of the flowers. After flower removal, the number of older more dangerous vector females in the population dropped to levels similar to those recorded in the villages that had no presence of the shrub. Villages infested with Prosopis juliflora also had a higher proportion of with a sugar meal in their gut, which enhances their survival. This proportion was reduced 5-fold following removal of the flowers.

According to the researchers, it may be worthwhile to abstain from the introduction of exotic plants that have the potential to become invasive, not only because of their potential negative impacts on the environment and livelihoods, but because some of them may have negative significant consequences for public health and specifically for malaria.

Explore further: Reported 'Odyssean' malaria cases not linked to new malaria vector discovery

More information: Gunter C. Muller et al, The invasive shrub Prosopis juliflora enhances the malaria parasite transmission capacity of Anopheles mosquitoes: a habitat manipulation experiment, Malaria Journal (2017). DOI: 10.1186/s12936-017-1878-9

Related Stories

Reported 'Odyssean' malaria cases not linked to new malaria vector discovery

March 13, 2017
A new malaria vector discovered in South Africa is not linked to the 'Odyssean' malaria cases reported in two provinces this week.

Trapped Amazonian mosquitos reveal their last meals: humans, birds, and small mammals

February 23, 2017
The mosquito Anopheles darlingi is the main vector of malaria in Central and South America, but little has been investigated about its behavior. Now, researchers, reporting in PLOS Neglected Tropical Diseases, have used traps ...

The malaria mosquito is disappearing -- but it is not just good news

August 25, 2011
The incidence of malaria in many African countries south of the Sahara is falling rapidly. A Danish-Tanzanian research group has discovered that the mosquito carrying the malaria parasite has practically disappeared from ...

Recommended for you

Two Group A Streptococcus genes linked to 'flesh-eating' bacterial infections

September 22, 2017
Group A Streptococcus bacteria cause a variety of illnesses that range from mild nuisances like strep throat to life-threatening conditions including pneumonia, toxic shock syndrome and the flesh-eating disease formally known ...

Ecosystem approach makes urinary tract infection more treatable

September 22, 2017
The biological term 'ecosystem' is not usually associated with urinary tract infections, but this should change according to Wageningen scientists.

Residents: Frontline defenders against antibiotic resistance?

September 22, 2017
Antibiotic resistance continues to grow around the world, with sometimes disastrous results. Some strains of bacteria no longer respond to any currently available antibiotic, making death by infections that were once easily ...

Individualized diets for irritable bowel syndrome better than placebo

September 21, 2017
Patients with irritable bowel syndrome who follow individualized diets based on food sensitivity testing experience fewer symptoms, say Yale researchers. Their study is among the first to provide scientific evidence for this ...

Superbug's spread to Vietnam threatens malaria control

September 21, 2017
A highly drug resistant malaria 'superbug' from western Cambodia is now present in southern Vietnam, leading to alarming failure rates for dihydroartemisinin (DHA)-piperaquine—Vietnam's national first-line malaria treatment, ...

Investigators may unlock mystery of how staph cells dodge the body's immune system

September 21, 2017
For years, medical investigators have tried and failed to develop vaccines for a type of staph bacteria associated with the deadly superbug MRSA. But a new study by Cedars-Sinai investigators shows how staph cells evade the ...

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.