Copulation activity, sperm production and conidia transfer in Aedes aegypti males contaminated by Metarhizium anisopliae: a biological control prospect

Garza-Hernández, Javier A., Reyes-Villanueva, Filiberto, Russell, Tanya L., Braks, Marieta A.H., Garcia-Munguia, Alberto M., and Rodríguez-Pérez, Mario A. (2015) Copulation activity, sperm production and conidia transfer in Aedes aegypti males contaminated by Metarhizium anisopliae: a biological control prospect. PLoS Neglected Tropical Diseases, 9 (10). e0004144. pp. 1-14.

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Abstract

Background: Dengue is the most prevalent arboviral disease transmitted by Aedes aegypti worldwide, whose chemical control is difficult, expensive, and of inconsistent efficacy. Releases of Metarhizium anisopliae—exposed Ae. aegypti males to disseminate conidia among female mosquitoes by mating represents a promising biological control approach against this important vector. A better understanding of fungus virulence and impact on reproductive parameters of Ae. aegypti, is need before testing auto-dissemination strategies.

Methodology/Principal Findings: Mortality, mating competitiveness, sperm production, and the capacity to auto-disseminate the fungus to females up to the 5thcopulation, were compared between Aedes aegypti males exposed to 5.96 x 107 conidia per cm2 of M. anisopliae and uninfected males. Half (50%) of fungus-exposed males (FEMs) died within the first 4 days post-exposure (PE). FEMs required 34% more time to successively copulate with 5 females (165 ± 3 minutes) than uninfected males (109 ± 3 minutes). Additionally, fungus infection reduced the sperm production by 87% at 5 days PE. Some beneficial impacts were observed, FEMs were able to successfully compete with uninfected males in cages, inseminating an equivalent number of females (about 25%). Under semi-field conditions, the ability of FEMs to search for and inseminate females was also equivalent to uninfected males (both inseminating about 40% females); but for the remaining females that were not inseminated, evidence of tarsal contact (transfer of fluorescent dust) was significantly greater in FEMs compared to controls. The estimated conidia load of a female exposed on the 5th copulation was 5,200 mL-1 which was sufficient to cause mortality.

Conclusion/Significance: Our study is the first to demonstrate auto-dissemination of M. anisopliae through transfer of fungus from males to female Ae. aegypti during mating under semi-field conditions. Our results suggest that auto-dissemination studies using releases of FEMs inside households could successfully infect wild Ae. aegypti females, providing another viable biological control tool for this important the dengue vector.

Item ID: 41140
Item Type: Article (Research - C1)
ISSN: 1935-2735
Additional Information:

© 2015 Garza-Hernández et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

Funders: Consejo Nacional de Ciencia y Technología, Mexico (CONACYT)
Projects and Grants: CONACYT CB2011-168394, CONACYT S008-2013-200664
Date Deposited: 03 Nov 2015 03:33
FoR Codes: 10 TECHNOLOGY > 1002 Environmental Biotechnology > 100202 Biological Control @ 80%
11 MEDICAL AND HEALTH SCIENCES > 1117 Public Health and Health Services > 111799 Public Health and Health Services not elsewhere classified @ 20%
SEO Codes: 96 ENVIRONMENT > 9604 Control of Pests, Diseases and Exotic Species > 960405 Control of Pests, Diseases and Exotic Species at Regional or Larger Scales @ 20%
92 HEALTH > 9204 Public Health (excl. Specific Population Health) > 920499 Public Health (excl. Specific Population Health) not elsewhere classified @ 80%
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