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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

M.anisopliae conidia attached to front tarsal segments of a male of Ae. aegypti.Intersection of gray line denotes the conidia layer pasted on the tarsi and white arrows show the polyhedronic shapes of conidia clusters which appeared pasted on tarsal segments.
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pntd.0004144.g006: M.anisopliae conidia attached to front tarsal segments of a male of Ae. aegypti.Intersection of gray line denotes the conidia layer pasted on the tarsi and white arrows show the polyhedronic shapes of conidia clusters which appeared pasted on tarsal segments.

Mentions: The LSM of conidia per pool varied significantly between treatments (F = 63.51, df = 2, p< 0.0001) in the model. The ratio Pearson χ2/freedom degrees of the NB goodness of fit test was 0.29. The LSM estimated per pool of three FEMs was 147,866± 21,064 mL-1, equivalent to 49,288 ±7,021 mL-1 per individual FEM. The SEM photograph indicated that conidia layers and clumps of polyhedronic shape of conidia remained attached on cuticle of front tarsi (Fig 6). The LSM conidial load per pool of 3 females from those that participated in the 1st copulation was of 31,348 ± 4,507 spores mL-1(10,449 ± 1,502 mL-1 per individual female), whilst the same for those involved in the 5th copulation was 15,811 ± 2,285 conidia mL-1(5,270 ± 761 mL-1 per individual female). Therefore, the conidial load of females of the 5th copulation was 50% lower than for females from the 1st copulation, and only 10% of the conidial load of 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)

M.anisopliae conidia attached to front tarsal segments of a male of Ae. aegypti.Intersection of gray line denotes the conidia layer pasted on the tarsi and white arrows show the polyhedronic shapes of conidia clusters which appeared pasted on tarsal segments.
© Copyright Policy
Related In: Results  -  Collection

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

pntd.0004144.g006: M.anisopliae conidia attached to front tarsal segments of a male of Ae. aegypti.Intersection of gray line denotes the conidia layer pasted on the tarsi and white arrows show the polyhedronic shapes of conidia clusters which appeared pasted on tarsal segments.
Mentions: The LSM of conidia per pool varied significantly between treatments (F = 63.51, df = 2, p< 0.0001) in the model. The ratio Pearson χ2/freedom degrees of the NB goodness of fit test was 0.29. The LSM estimated per pool of three FEMs was 147,866± 21,064 mL-1, equivalent to 49,288 ±7,021 mL-1 per individual FEM. The SEM photograph indicated that conidia layers and clumps of polyhedronic shape of conidia remained attached on cuticle of front tarsi (Fig 6). The LSM conidial load per pool of 3 females from those that participated in the 1st copulation was of 31,348 ± 4,507 spores mL-1(10,449 ± 1,502 mL-1 per individual female), whilst the same for those involved in the 5th copulation was 15,811 ± 2,285 conidia mL-1(5,270 ± 761 mL-1 per individual female). Therefore, the conidial load of females of the 5th copulation was 50% lower than for females from the 1st copulation, and only 10% of the conidial load of 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