Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
. 2025 May 22:9:290.
doi: 10.12688/wellcomeopenres.21238.3. eCollection 2024.

Entomopathogenic fungi Metarhizium pingshaense increases susceptibility to insecticides in highly resistant malaria mosquitoes Anopheles coluzzii

Doubé Lucien Lamy  1   2   3 , Edounou Jacques Gnambani  1   3 , Issiaka Sare  1   3   4 , Souro Abel Millogo  1   2   3 , Fatimata Aïcha Sodre  1   2   3 , Moussa Namountougou  1   2   3 , Mafalda Viana  5 , Francesco Baldini  5   6 , Abdoulaye Diabaté  1   3 , Etienne Bilgo  1   3
Affiliations

Entomopathogenic fungi Metarhizium pingshaense increases susceptibility to insecticides in highly resistant malaria mosquitoes Anopheles coluzzii

Doubé Lucien Lamy et al. Wellcome Open Res. .

Abstract

Background: Metarhizium spp. based mosquito control products are among the most investigated and could potentially serve as promising complements to chemical insecticides. However, limited knowledge exists on the implementation of this biocontrol tool in conjunction with primary insecticide-based strategies to achieve synergy.

Methods: In laboratory bioassays, we combined 10 7 conidia/ml native Metarhizium pingshaense strains with deltamethrin standard dose in two ways : before and after insecticide exposure. For comparison, some mosquitoes were exposed to deltamethrin or fungi alone. These combinations were tested on laboratory insecticide resistant Anopheles coluzzii.

Results: We found that Metarhizium pingshaense and deltamethrin could be combined to achieve greater mortality against a highly insecticide resistance colony of Anopheles coluzzii. Specifically, when fungi were applied earlier than deltamethrin, mosquitoes became more sensitive to insecticide with a minimum Lethal Time to kill at least 50% of mosquito population (LT50) less than 8 days. In addition, when deltamethrin exposure was followed by Metarhizium infection, mosquito survival was similar to Metarhizium alone LT50 (LT50 ~11 days).

Conclusion: These findings suggest that early mosquito infection to Metarhizium pingshaense followed by chemical insecticide exposure synergically increased mosquito susceptibility to the insecticide in the laboratory.

Keywords: Anopheles coluzzii; Burkina Faso; Deltamethrin; Insecticide resistance; Integrated vector control; Metarhizium pingshaense.

Plain language summary

Mosquito control products that use fungal spores as active ingredients known as Metarhizium are currently under investigation. These have demonstrated the potential to eliminate mosquitoes that are vectors of malaria. Furthermore, these products could potentially be utilised in conjunction with conventional chemical insecticides. This is particularly important now as mosquitoes are becoming not affected by chemicals and new solutions are needed. Our hypothesis is that these fungi could increase mosquitoes vulnerability to chemical insecticide. To prove this, we tested three ways of combining this fungus with a common chemical insecticide (deltamethrin): treating mosquito with the fungus before, after, or at the same time as the insecticide. Our tests were conducted in the laboratory using a mosquito specie that transmit malaria, which is also less vulnerable to chemicals. We found that treating mosquitoes with fungus and then exposing them with the insecticide makes them more likely to be killed by the chemical. Our research indicates that this fungus can work together with chemical insecticides to help fight against mosquitoes that have become resistant to our usual insecticides, offering a new way to tackle malaria spread.

PubMed Disclaimer

Conflict of interest statement

No competing interests were disclosed.

Figures

Figure 1.
Figure 1.. Schematic of the experimental design.
This diagram illustrates the two combination sequences used to evaluate the effects of Metarhizium pingshaense and deltamethrin combination on insecticide resistant Anopheles coluzzii mosquitoes: ( A) control, spread with fungal free tween solution ( B) fungal infection only; ( C) Deltamethrin only exposure; ( D) Deltamethrin exposure followed by fungus infection; and ( E) fungal infection followed by deltamethrin exposure.
Figure 2.
Figure 2.. Mean percentage mortality of insecticide-resistant An. coluzzii VKPER infected with native Metarhizium strains 14 days after treatment.
Three Metarhizium strains were used: two reference strains (S10 and S26), and a newly isolated strain (S31). Mortality was significantly higher in fungus-treated groups, regardless of the fungal strain, compared to the control group.
Figure 3.
Figure 3.. Effect of Metarhizium and deltamethrin on survival in insecticide-resistant Anopheles mosquitoes.
Metarhizium and deltamethrin applied separately ( A). Deltamethrin followed by Metarhizium ( B). Metarhizium followed by deltamethrin ( C).
See this image and copyright information in PMC

Similar articles

See all similar articles

References

    1. Alout H, Dabire RK, Djogbenou LS, et al. : Interactive cost of Plasmodium infection and insecticide resistance in the malaria vector Anopheles gambiae . Sci Rep. 2016;19: 29755. 10.1038/srep29755 - DOI - PMC - PubMed
    1. Aw KMS, Hue SM: Mode of infection of Metarhizium spp. fungus and their potential as biological control agents. J Fungi (Basel). 2017;3(2):30. 10.3390/jof3020030 - DOI - PMC - PubMed
    1. Baró Y, Schuster C, Gato Y, et al. : Characterization, identification and virulence of Metarhizium species from cuba to control the sweet potato weevil, Cylas formicarius fabricius (Coleoptera: Brentidae). J Appl Microbiol. 2022;132(5):3705–16. 10.1111/jam.15460 - DOI - PubMed
    1. Beier JC, Keating J, Githure JI, et al. : Integrated vector management for malaria control. Malar J. 2008;7(S1): S4. 10.1186/1475-2875-7-S1-S4 - DOI - PMC - PubMed
    1. Bhatt S, Weiss DJ, Cameron E, et al. : The effect of malaria control on Plasmodium falciparum in Africa between 2000 and 2015. Nature. 2015;526(7572):207–211. 10.1038/nature15535 - DOI - PMC - PubMed

LinkOut - more resources