Copulation Activity, Sperm Production and Conidia Transfer in Aedes aegypti Males Contaminated by Metarhizium anisopliae: A Biological Control Prospect
| Autor: | Tanya L. Russell, Javier A. Garza-Hernández, Alberto M. Garcia-Munguia, Filiberto Reyes-Villanueva, Marieta A. H. Braks, Mario A. Rodríguez-Pérez |
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| Jazyk: | angličtina |
| Rok vydání: | 2015 |
| Předmět: |
Male
Veterinary medicine Metarhizium lcsh:Arctic medicine. Tropical medicine Mosquito Control lcsh:RC955-962 Colony Count Microbial Metarhizium anisopliae Aedes aegypti Insemination Conidium Aedes Botany Copulation Animals Mating Pest Control Biological Spermatogenesis biology lcsh:Public aspects of medicine fungi Public Health Environmental and Occupational Health lcsh:RA1-1270 Spores Fungal biology.organism_classification Sperm Survival Analysis Infectious Diseases Female Research Article |
| Zdroj: | PLoS Neglected Tropical Diseases PLoS Neglected Tropical Diseases, Vol 9, Iss 10, p e0004144 (2015) |
| ISSN: | 1935-2735 1935-2727 |
| Popis: | 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. Author Summary Dengue virus (four serotypes) is transmitted primarily by the mosquitoes Aedes aegypti and currently 2.5 billion people are in risk of being infected. The incidence of this neglected disease is increasing in developing countries where communities have not been able to effectively remove mosquito sources and their economies cannot afford the vector chemical control. Our study is collecting some of the baseline information necessary to evaluate a novel biological control strategy that would release Ae. aegypti males mosquitoes infected with the fungus Metarhizium anisopliae. These fungus-infected males transfer the fungus to female mosquitoes through leg contact during the mating process (This is called auto-dissemination). The fungus killed 50% of males within 4 days of being exposed. The fungus infection also increase the time that males need to mate with 5 females mosquitoes and reduced the sperm production by 87% 5 days after being infected. The ability of fungus-exposed males (FEMs) to find and mate with females in the laboratory or a small greenhouse was the same as for uninfected males. In particular, in the small greenhouse FEMs made more mating attempts without insemination than the uninfected males (more than twice the attempts). During both attempts and successful matings, the FEMS were able to transfer fungus to females confirming that auto-dissemination does occur. We also showed that the amount of fungus transferred to female, even after the 5thmating (about 10% of male’s conidia load) was sufficient to kill 50% of females within 3 days. These results indicate that there is potential for auto-dissemination of M. anisopliae from males to females as a dengue control tool. |
| Databáze: | OpenAIRE |
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