Contribution of midgut bacteria to blood digestion and egg production in Aedes aegypti (diptera: culicidae) (L.)

Abstract

BackgroundThe insect gut harbors a variety of microorganisms that probably exceed the number of cells in insects themselves. These microorganisms can live and multiply in the insect, contributing to digestion, nutrition, and development of their host.Recent studies have shown that midgut bacteria appear to strengthen the mosquito's immune system and indirectly enhance protection from invading pathogens. Nevertheless, the physiological significance of these bacteria for mosquitoes has not been established to date. In this study, oral administration of antibiotics was employed in order to examine the contribution of gut bacteria to blood digestion and fecundity in Aedes aegypti.ResultsThe antibiotics carbenicillin, tetracycline, spectinomycin, gentamycin and kanamycin, were individually offered to female mosquitoes. Treatment of female mosquitoes with antibiotics affected the lysis of red blood cells (RBCs), retarded the digestion of blood proteins and reduced egg production. In addition, antibiotics did not affect the survival of mosquitoes. Mosquito fertility was restored in the second gonotrophic cycle after suspension of the antibiotic treatment, showing that the negative effects of antibiotics in blood digestion and egg production in the first gonotrophic cycle were reversible.ConclusionsThe reduction of bacteria affected RBC lysis, subsequently retarded protein digestion, deprived mosquito from essential nutrients and, finally, oocyte maturation was affected, resulting in the production of fewer viable eggs. These results indicate that Ae. aegypti and its midgut bacteria work in synergism to digest a blood meal.Our findings open new possibilities to investigate Ae. aegypti-associated bacteria as targets for mosquito control strategies.

Mosquito Microbiome Dynamics, a Background for Prevalence and Seasonality of West Nile Virus

“…Abundant Pseudomonas are commonly found across mosquito species (Charan et al, 2013; Minard et al, 2013). The presence of at least some bacterial strains, regardless of their origin, may be essential for successful mosquito development (Chouaia et al, 2012; Coon et al, 2014), digestion, and fecundity (Gaio et al, 2011). …”

Dynamics of midgut microflora and dengue virus impact on life history traits in Aedes aegypti

“…Egg production of microbially cleansed Ae. aegypti has been explored among females allowed to blood feed on mice (Gaio et al, 2011). After females were cleansed using single antibiotic treatments, oocytes and laid eggs were enumerated.…”

“…In the case of Ae. aegypti , the reduction of bacteria affected RBC lysis, subsequently retarded protein digestion, depleted nutrients availability and reduced fecundity (Gaio et al, 2011). Evidence for commensal specificity and coadaptation in Ae.…”

“…aegypti . Reduction of microbes with antibiotics resulted in delayed red blood cell lysis, impaired protein digestion and nutrient deprivation (Gaio et al, 2011). Oocyte maturation was also reduced due to microbe reduction.…”

The microbiome modulates arbovirus transmission in mosquitoes

“…For example, antibiotic treatment of larvae results in aborted development, however this effect can be rescued by bacterial supplementation [8 •• ,35]. In another case, bacteria isolated from the midgut of A. aegypti have been shown to influence blood digestion and egg development [36]. Parameters such as mosquito survival, development time, and reproductive capacity can have large influences on the population-level vectorial capacity for arboviruses that are equal or greater than the direct effects on vector competence.…”