Infection of the malaria mosquito, Anopheles gambiae s.s., with two species of entomopathogenic fungi: effects of concentration, co-formulation, exposure time and persistence

Mnyone, Ladslaus L., Kirby, Matthew J., Lwetoijera, Dickson W., Mpingwa, Monica W., Knols, Bart G.J., Takken, Willem, and Russell, Tanya L. (2009) Infection of the malaria mosquito, Anopheles gambiae s.s., with two species of entomopathogenic fungi: effects of concentration, co-formulation, exposure time and persistence. Malaria Journal, 8. 309.

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Abstract

Background: Entomopathogenic fungi Metarhizium anisopliae and Beauveria bassiana isolates have been shown to infect and reduce the survival of mosquito vectors.

Methods: Here four different bioassays were conducted to study the effect of conidia concentration, co-formulation, exposure time and persistence of the isolates M. anisopliae ICIPE-30 and B. bassiana I93-925 on infection and survival rates of female Anopheles gambiae sensu stricto. Test concentrations and exposure times ranged between 1 x 107 - 4 x 1010 conidia m-2 and 15 min - 6 h. In co-formulations, 2 x 1010 conidia m-2 of both fungus isolates were mixed at ratios of 4:1, 2:1, 1:1,1:0, 0:1, 1:2 and 1:4. To determine persistence, mosquitoes were exposed to surfaces treated 1, 14 or 28 d previously, with conidia concentrations of 2 x 109, 2 x 1010 or 4 x 1010.

Results: Mosquito survival varied with conidia concentration; 2 x 1010 conidia m-2 was the concentration above which no further reductions in survival were detectable for both isolates of fungus. The survival of mosquitoes exposed to single and co-formulated treatments was similar and no synergistic or additive effects were observed. Mosquitoes were infected within 30 min and longer exposure times did not result in a more rapid killing effect. Fifteen min exposure still achieved considerable mortality rates (100% mortality by 14 d) of mosquitoes, but at lower speed than with 30 min exposure (100% mortality by 9 d). Conidia remained infective up to 28 d post-application but higher concentrations did not increase persistence.

Conclusion: Both fungus isolates are effective and persistent at low concentrations and short exposure times.

Item ID: 34898
Item Type: Article (Research - C1)
ISSN: 1475-2875
Additional Information:

© 2009 Mnyone et al; licensee BioMed Central Ltd.

This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Funders: Addessium Foundation, The Netherlands
Date Deposited: 18 Sep 2014 04:12
FoR Codes: 10 TECHNOLOGY > 1002 Environmental Biotechnology > 100202 Biological Control @ 100%
SEO Codes: 92 HEALTH > 9204 Public Health (excl. Specific Population Health) > 920499 Public Health (excl. Specific Population Health) not elsewhere classified @ 50%
96 ENVIRONMENT > 9604 Control of Pests, Diseases and Exotic Species > 960405 Control of Pests, Diseases and Exotic Species at Regional or Larger Scales @ 50%
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