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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

Aedes aegypti mosquito adults marked with fluorescent powders.A: M. anisopliae-exposed male marked with red fluorescent powder. B: Uninfected male marked with yellow powder. C: A female mosquito that was mated by both fungus-exposed male and uninfected one, showing spots of powder of both colors on the last abdominal segments (red and yellow arrows).
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pntd.0004144.g001: Aedes aegypti mosquito adults marked with fluorescent powders.A: M. anisopliae-exposed male marked with red fluorescent powder. B: Uninfected male marked with yellow powder. C: A female mosquito that was mated by both fungus-exposed male and uninfected one, showing spots of powder of both colors on the last abdominal segments (red and yellow arrows).

Mentions: One FEM (marked with red dust), one uninfected male (marked with yellow dust) and 20 unmarked, uninseminated females were placed in a 1-liter plastic bottle, and confined together from 16:00 h to 19:00 h. At 19:00 h the mosquitoes were immobilized and the females were collected for dissection and removal of the spermathecae, which were examined for evidence of insemination. Before dissection the female mosquitoes were examined using a UV light for the presence of fluorescent powder transfer on to the last abdominal segment (Fig 1). Females were scored into the following four nominal response variable (RV) categories: Inseminated by FEM (red powder), inseminated by uninfected male (yellow powder), inseminated and encountered by both FEM and uninfected males (both red and yellow powder), and uninseminated females not contacted by any male (no powder). Ten replicates were carried out on different days all with a mixture of mosquitoes 4–7 days old.


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)

Aedes aegypti mosquito adults marked with fluorescent powders.A: M. anisopliae-exposed male marked with red fluorescent powder. B: Uninfected male marked with yellow powder. C: A female mosquito that was mated by both fungus-exposed male and uninfected one, showing spots of powder of both colors on the last abdominal segments (red and yellow arrows).
© Copyright Policy
Related In: Results  -  Collection

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

pntd.0004144.g001: Aedes aegypti mosquito adults marked with fluorescent powders.A: M. anisopliae-exposed male marked with red fluorescent powder. B: Uninfected male marked with yellow powder. C: A female mosquito that was mated by both fungus-exposed male and uninfected one, showing spots of powder of both colors on the last abdominal segments (red and yellow arrows).
Mentions: One FEM (marked with red dust), one uninfected male (marked with yellow dust) and 20 unmarked, uninseminated females were placed in a 1-liter plastic bottle, and confined together from 16:00 h to 19:00 h. At 19:00 h the mosquitoes were immobilized and the females were collected for dissection and removal of the spermathecae, which were examined for evidence of insemination. Before dissection the female mosquitoes were examined using a UV light for the presence of fluorescent powder transfer on to the last abdominal segment (Fig 1). Females were scored into the following four nominal response variable (RV) categories: Inseminated by FEM (red powder), inseminated by uninfected male (yellow powder), inseminated and encountered by both FEM and uninfected males (both red and yellow powder), and uninseminated females not contacted by any male (no powder). Ten replicates were carried out on different days all with a mixture of mosquitoes 4–7 days old.

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