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Copulation Activity, Sperm Production and Conidia Transfer in Aedes aegypti Males Contaminated by Metarhizium anisopliae: A Biological Control Prospect.

Garza-Hernández JA, Reyes-Villanueva F, Russell TL, Braks MA, Garcia-Munguia AM, Rodríguez-Pérez MA - PLoS Negl Trop Dis (2015)

Bottom Line: 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.

View Article: PubMed Central - PubMed

Affiliation: Laboratorio de Biomedicina Molecular, Centro de Biotecnología Genómica, Instituto Politécnico Nacional, Tamaulipas, México.

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 5 th copulation, were compared between Aedes aegypti males exposed to 5.96 x 10(7) 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.

No MeSH data available.


Related in: MedlinePlus

Greenhouse to evaluate copulation activity of M. anisopliae-exposed and uninfected Ae. aegypti males with female mosquitoes.A wood floor was added to the structure to facilitate detecting dead mosquitoes on it; the greenhouse was at the Centro de Biotecnología Genómica, Instituto Politécnico Nacional, Reynosa, Mexico.
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pntd.0004144.g002: Greenhouse to evaluate copulation activity of M. anisopliae-exposed and uninfected Ae. aegypti males with female mosquitoes.A wood floor was added to the structure to facilitate detecting dead mosquitoes on it; the greenhouse was at the Centro de Biotecnología Genómica, Instituto Politécnico Nacional, Reynosa, Mexico.

Mentions: For each replicate, a single male Ae. aegypti (FEM or uninfected) was confined with 20 females in a small greenhouse constructed of gauze and cotton walls (6 x 3 x 2.80 meters) (Fig 2). This experiment examined the ability of FEMs to search for female mates in a large space and compared the copulation activity with that of an uninfected male. As with the laboratory experiments, the male (FEM or uninfected) and female mosquitoes were confined from 16:00 h to 19:00 h after which all of the mosquitoes were captured with a mouth aspirator. The females were then inspected with a UV light for florescent powder and the spermathecae were dissected to record insemination. First, 10 replicates conducted over 10 sequential days were carried out for uninfected males (yellow powder). After 5 days, the same process was carried out for FEMs (red powder). In contrast to the laboratory assay, 5 categories of the nominal RV were recorded: Inseminated by FEM, mating attempts made by FEM (where female remains uninseminated), inseminated by uninfected male, mating attempts by uninfected male, and uninseminated females not contacted by any male. A digital higrothermometer was placed into the greenhouse to register both temperature and relative humidity (RH) during the 3-hour interval of activity of the released males.


Copulation Activity, Sperm Production and Conidia Transfer in Aedes aegypti Males Contaminated by Metarhizium anisopliae: A Biological Control Prospect.

Garza-Hernández JA, Reyes-Villanueva F, Russell TL, Braks MA, Garcia-Munguia AM, Rodríguez-Pérez MA - PLoS Negl Trop Dis (2015)

Greenhouse to evaluate copulation activity of M. anisopliae-exposed and uninfected Ae. aegypti males with female mosquitoes.A wood floor was added to the structure to facilitate detecting dead mosquitoes on it; the greenhouse was at the Centro de Biotecnología Genómica, Instituto Politécnico Nacional, Reynosa, Mexico.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4608813&req=5

pntd.0004144.g002: Greenhouse to evaluate copulation activity of M. anisopliae-exposed and uninfected Ae. aegypti males with female mosquitoes.A wood floor was added to the structure to facilitate detecting dead mosquitoes on it; the greenhouse was at the Centro de Biotecnología Genómica, Instituto Politécnico Nacional, Reynosa, Mexico.
Mentions: For each replicate, a single male Ae. aegypti (FEM or uninfected) was confined with 20 females in a small greenhouse constructed of gauze and cotton walls (6 x 3 x 2.80 meters) (Fig 2). This experiment examined the ability of FEMs to search for female mates in a large space and compared the copulation activity with that of an uninfected male. As with the laboratory experiments, the male (FEM or uninfected) and female mosquitoes were confined from 16:00 h to 19:00 h after which all of the mosquitoes were captured with a mouth aspirator. The females were then inspected with a UV light for florescent powder and the spermathecae were dissected to record insemination. First, 10 replicates conducted over 10 sequential days were carried out for uninfected males (yellow powder). After 5 days, the same process was carried out for FEMs (red powder). In contrast to the laboratory assay, 5 categories of the nominal RV were recorded: Inseminated by FEM, mating attempts made by FEM (where female remains uninseminated), inseminated by uninfected male, mating attempts by uninfected male, and uninseminated females not contacted by any male. A digital higrothermometer was placed into the greenhouse to register both temperature and relative humidity (RH) during the 3-hour interval of activity of the released males.

Bottom Line: 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.

View Article: PubMed Central - PubMed

Affiliation: Laboratorio de Biomedicina Molecular, Centro de Biotecnología Genómica, Instituto Politécnico Nacional, Tamaulipas, México.

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 5 th copulation, were compared between Aedes aegypti males exposed to 5.96 x 10(7) 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.

No MeSH data available.


Related in: MedlinePlus