such as "Introduction", "Conclusion"..etc
In areas where malaria mosquitoes have become resistant to chemical
pesticides, mosquito-killing fungi can be an effective tool. Fungal
spores can effectively infect and kill malaria mosquitoes, even those
that are resistant to pesticides. Moreover, the mosquitoes become more
susceptible to the pesticides as the fungal infection increases.
Researchers from Wageningen University and their colleagues from
South Africa have published an article on this effect in the journal PNAS
(Proceedings of the National Academy of Sciences) of this
Malaria mosquitoes are becoming increasingly resistant to pesticides.
As a result, malaria is difficult to control. Besides the existing
chemical pesticides such as DDT and pyrethroids, which are applied
indoors and on mosquito nets, there are few options for mosquito
control. The use of insect-killing fungi is a novel biological control
method for malaria mosquitoes that was developed in 2005 in cooperation
with Wageningen researchers. The spores of the fungi can infect
mosquitoes upon contact and kill them within several days. Moreover, a
fungal infection reduces the mosquito's appetite and slows the
development of malaria parasites inside the mosquito.
Together with her colleagues in South Africa, the Wageningen
researcher Marit Farenhorst tested these fungi for the first time on
various species of pesticide-resistant malaria mosquitoes. In the
laboratory in Johannesburg, the research team compared the effectiveness
of fungi on mosquitoes that are susceptible to insecticides and their
relatives who are resistant. The fungus Beauveria bassiana was
able to kill both susceptible and resistant malaria mosquitoes. This
indicates that malaria mosquitoes that are resistant to the pesticide
are not resistant to the fungus.
In addition, the team studied to what extent mosquitoes that are
infected with the fungus are also susceptible to pesticides. To this
end, resistant mosquitoes were infected with spores of the fungi Beauveria
bassiana or Metarhizium anisopliae. After three days of
incubation, they were tested for their resistance to the pesticides
permethrin and DDT. Both fungus species increased the mosquitoes‘
susceptibility to these agents; more mosquitoes died after exposure to
the chemicals when they were infected with fungus. The researchers
believe that the toxins excreted by the fungi undermine the mosquitoes'
Biological mosquito control
The results show the potential of fungi as an effective and
sustainable biological control agent for malaria mosquitoes. Due to the
increasing problem of pesticide resistance in Africa, they offer a
crucial alternative for current control methods.
Because infected mosquitoes die slowly, within several days, they are
still capable of reproducing. As a result, there is much less chance of
their offspring becoming resistant to fungi. According to the
researchers, the relatively slow effect of the fungi is sufficient to
block transmission of malaria. On average, it takes 10-14 days before a
mosquito that has acquired the malaria parasite during a blood meal can
transmit the disease to another person. "In fact you only kill 'old'
mosquitoes, and these are actually the most dangerous ones!", explains
researcher Bart Knols.
Because fungi enhance the effectiveness of pesticides against
resistant mosquitoes, the researchers see a fungus-pesticide combination
as an important addition to the limited arsenal of anti-malaria
Worldwide, more than one million people die every year from malaria,
primarily African children less than five years old and pregnant women.
More than 3 billion people live in regions where there is a risk of
malaria infection, and every year more than 500 million people suffer
from an infection. The disease is transmitted by mosquitoes, and
mosquito control takes place with mosquito nets that are treated with a
pesticide or by applying pesticides to the indoor walls.
Resistance to the standard agents that are used for mosquito control,
primarily resistance to the so-called pyrethroids that are used to
impregnate mosquito netting, is becoming increasingly widespread,
especially in West Africa. In some countries, such as Benin, treated
mosquito nets and indoor spraying no longer offer sufficient protection.
During the past 20 years, no chemical alternative has appeared on the
market, and the possibilities for controlling the mosquitoes
biologically (with fungi) is seen as a sustainable alternative to avoid
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