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Infection of malaria (Anopheles gambiae s.s.) and filariasis (Culex quinquefasciatus) vectors with the entomopathogenic fungus Metarhizium anisopliae.

Scholte EJ, Njiru BN, Smallegange RC, Takken W, Knols BG - Malar. J. (2003)

Bottom Line: No differences in LT50 values were found for different exposure times (24, 48 hrs or continuous exposure) of An. gambiae to dry conidia.Our study marks the first to use an entomopathogenic fungus against adult Afrotropical disease vectors.Given its high pathogenicity for both adult Anopheles and Culex mosquitoes we recommend development of novel targeted indoor application methods for the control of endophagic host-seeking females.

View Article: PubMed Central - HTML - PubMed

Affiliation: Laboratory of Entomology, Wageningen University & Research Centre, PO Box 8031, 6700 EH, Wageningen, the Netherlands. ErnstJan.Scholte@wur.nl

ABSTRACT

Background: Current intra-domiciliary vector control depends on the application of residual insecticides and/or repellents. Although biological control agents have been developed against aquatic mosquito stages, none are available for adults. Following successful use of an entomopathogenic fungus against tsetse flies (Diptera: Glossinidae) we investigated the potency of this fungus as a biological control agent for adult malaria and filariasis vector mosquitoes.

Methods: In the laboratory, both sexes of Anopheles gambiae sensu stricto and Culex quinquefasciatus were passively contaminated with dry conidia of Metarhizium anisopliae. Pathogenicity of this fungus for An. gambiae was further tested for varying exposure times and different doses of oil-formulated conidia.

Results: Comparison of Gompertz survival curves and LT50 values for treated and untreated specimens showed that, for both species, infected mosquitoes died significantly earlier (p < 0.0001) than uninfected control groups. No differences in LT50 values were found for different exposure times (24, 48 hrs or continuous exposure) of An. gambiae to dry conidia. Exposure to oil-formulated conidia (doses ranging from 1.6 x 10(7) to 1.6 x 10(10) conidia/m2) gave LT50 values of 9.69 +/- 1.24 (lowest dose) to 5.89 +/- 0.35 days (highest dose), with infection percentages ranging from 4.4-83.7%.

Conclusion: Our study marks the first to use an entomopathogenic fungus against adult Afrotropical disease vectors. Given its high pathogenicity for both adult Anopheles and Culex mosquitoes we recommend development of novel targeted indoor application methods for the control of endophagic host-seeking females.

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Gompertz survival curves for adult male and female Anopheles gambiae s.s. infected with dry conidia of the entomopathogenic fungus Metarhizium anisopliae (pooled data for 24/48 hrs or continuous exposure).
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Figure 2: Gompertz survival curves for adult male and female Anopheles gambiae s.s. infected with dry conidia of the entomopathogenic fungus Metarhizium anisopliae (pooled data for 24/48 hrs or continuous exposure).

Mentions: Mosquito survival data from all three bioassays closely fitted the Gompertz distribution model (variance accounted for ranged from 96.2–99.6%; Figure 2 and 3). Estimates of daily survival rates derived from the Gompertz model [49] showed a dramatic reduction following exposure to conidia. In the dose-response experiment, daily survival rates were inversely related to the exposure dose. Table 3 shows estimated daily survival rates for An. gambiae at different ages for the doses tested.


Infection of malaria (Anopheles gambiae s.s.) and filariasis (Culex quinquefasciatus) vectors with the entomopathogenic fungus Metarhizium anisopliae.

Scholte EJ, Njiru BN, Smallegange RC, Takken W, Knols BG - Malar. J. (2003)

Gompertz survival curves for adult male and female Anopheles gambiae s.s. infected with dry conidia of the entomopathogenic fungus Metarhizium anisopliae (pooled data for 24/48 hrs or continuous exposure).
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC222926&req=5

Figure 2: Gompertz survival curves for adult male and female Anopheles gambiae s.s. infected with dry conidia of the entomopathogenic fungus Metarhizium anisopliae (pooled data for 24/48 hrs or continuous exposure).
Mentions: Mosquito survival data from all three bioassays closely fitted the Gompertz distribution model (variance accounted for ranged from 96.2–99.6%; Figure 2 and 3). Estimates of daily survival rates derived from the Gompertz model [49] showed a dramatic reduction following exposure to conidia. In the dose-response experiment, daily survival rates were inversely related to the exposure dose. Table 3 shows estimated daily survival rates for An. gambiae at different ages for the doses tested.

Bottom Line: No differences in LT50 values were found for different exposure times (24, 48 hrs or continuous exposure) of An. gambiae to dry conidia.Our study marks the first to use an entomopathogenic fungus against adult Afrotropical disease vectors.Given its high pathogenicity for both adult Anopheles and Culex mosquitoes we recommend development of novel targeted indoor application methods for the control of endophagic host-seeking females.

View Article: PubMed Central - HTML - PubMed

Affiliation: Laboratory of Entomology, Wageningen University & Research Centre, PO Box 8031, 6700 EH, Wageningen, the Netherlands. ErnstJan.Scholte@wur.nl

ABSTRACT

Background: Current intra-domiciliary vector control depends on the application of residual insecticides and/or repellents. Although biological control agents have been developed against aquatic mosquito stages, none are available for adults. Following successful use of an entomopathogenic fungus against tsetse flies (Diptera: Glossinidae) we investigated the potency of this fungus as a biological control agent for adult malaria and filariasis vector mosquitoes.

Methods: In the laboratory, both sexes of Anopheles gambiae sensu stricto and Culex quinquefasciatus were passively contaminated with dry conidia of Metarhizium anisopliae. Pathogenicity of this fungus for An. gambiae was further tested for varying exposure times and different doses of oil-formulated conidia.

Results: Comparison of Gompertz survival curves and LT50 values for treated and untreated specimens showed that, for both species, infected mosquitoes died significantly earlier (p < 0.0001) than uninfected control groups. No differences in LT50 values were found for different exposure times (24, 48 hrs or continuous exposure) of An. gambiae to dry conidia. Exposure to oil-formulated conidia (doses ranging from 1.6 x 10(7) to 1.6 x 10(10) conidia/m2) gave LT50 values of 9.69 +/- 1.24 (lowest dose) to 5.89 +/- 0.35 days (highest dose), with infection percentages ranging from 4.4-83.7%.

Conclusion: Our study marks the first to use an entomopathogenic fungus against adult Afrotropical disease vectors. Given its high pathogenicity for both adult Anopheles and Culex mosquitoes we recommend development of novel targeted indoor application methods for the control of endophagic host-seeking females.

Show MeSH
Related in: MedlinePlus