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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

Daily number of Ae. aegypti female mosquitoes mated by a fungus-exposed and an uninfected male in a greenhouse.Data are the least square means (LSMs) ± standard error (SE) number of Ae. aegypti female mosquitoes in five “copulation status” (combination of insemination or not/M. anisopliae-infection). LSMs were calculated by a glimmix model from 10 replicates. Different letters above bars denote significant differences (p < 0.05) accordingly to pair-wise t tests conducted by Tukey-Cramer multiple comparisons.
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pntd.0004144.g004: Daily number of Ae. aegypti female mosquitoes mated by a fungus-exposed and an uninfected male in a greenhouse.Data are the least square means (LSMs) ± standard error (SE) number of Ae. aegypti female mosquitoes in five “copulation status” (combination of insemination or not/M. anisopliae-infection). LSMs were calculated by a glimmix model from 10 replicates. Different letters above bars denote significant differences (p < 0.05) accordingly to pair-wise t tests conducted by Tukey-Cramer multiple comparisons.

Mentions: In the small greenhouse, there was no difference in the ability of FEMs and uninfected males to search for and contact females. The LSMs number of females were not affected by treatment and day, but only by copulation status (F = 9.31, df = 4, p<0.0001) in the model, which was robust with a ratio Pearson χ2/ freedom degrees of 0.69; that is there was no statistical difference between the average number females inseminated by FEMs (9.86 ± 1.44) or controls (8.17 ± 1.17). Furthermore the number of females that were grasped (marked with red powder) but not inseminated (copulation attempts) by FEMs (7.48 ± 1.18) was greater than controls (with yellow powder) captured by uninfected males (3.25 ± 0.62); though both groups did not differ from total females (with no powder marking) that were not contacted by any male (5.10 ± 0.50) (Fig 4). During this experiment the daily temperature varied between 28°C and 35°C, and RH between 68 and 88%.


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)

Daily number of Ae. aegypti female mosquitoes mated by a fungus-exposed and an uninfected male in a greenhouse.Data are the least square means (LSMs) ± standard error (SE) number of Ae. aegypti female mosquitoes in five “copulation status” (combination of insemination or not/M. anisopliae-infection). LSMs were calculated by a glimmix model from 10 replicates. Different letters above bars denote significant differences (p < 0.05) accordingly to pair-wise t tests conducted by Tukey-Cramer multiple comparisons.
© Copyright Policy
Related In: Results  -  Collection

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

pntd.0004144.g004: Daily number of Ae. aegypti female mosquitoes mated by a fungus-exposed and an uninfected male in a greenhouse.Data are the least square means (LSMs) ± standard error (SE) number of Ae. aegypti female mosquitoes in five “copulation status” (combination of insemination or not/M. anisopliae-infection). LSMs were calculated by a glimmix model from 10 replicates. Different letters above bars denote significant differences (p < 0.05) accordingly to pair-wise t tests conducted by Tukey-Cramer multiple comparisons.
Mentions: In the small greenhouse, there was no difference in the ability of FEMs and uninfected males to search for and contact females. The LSMs number of females were not affected by treatment and day, but only by copulation status (F = 9.31, df = 4, p<0.0001) in the model, which was robust with a ratio Pearson χ2/ freedom degrees of 0.69; that is there was no statistical difference between the average number females inseminated by FEMs (9.86 ± 1.44) or controls (8.17 ± 1.17). Furthermore the number of females that were grasped (marked with red powder) but not inseminated (copulation attempts) by FEMs (7.48 ± 1.18) was greater than controls (with yellow powder) captured by uninfected males (3.25 ± 0.62); though both groups did not differ from total females (with no powder marking) that were not contacted by any male (5.10 ± 0.50) (Fig 4). During this experiment the daily temperature varied between 28°C and 35°C, and RH between 68 and 88%.

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