RESUMO
We show for the first time that the ventral diverticulum of the mosquito gut (impermeable sugar storage organ) harbors microorganisms. The gut diverticulum from newly emerged and non-fed Aedes aegypti was dissected under aseptic conditions, homogenized and plated on BHI medium. Microbial isolates were identified by sequencing of 16S rDNA for bacteria and 28S rDNA for yeast. A direct DNA extraction from Ae. aegypti gut diverticulum was also performed. The bacterial isolates were: Bacillus sp., Bacillus subtilis and Serratia sp. The latter was the predominant bacteria found in our isolations. The yeast species identified was Pichia caribbica.
Assuntos
Animais , Aedes/microbiologia , Bacillus/isolamento & purificação , Trato Gastrointestinal/microbiologia , Pichia/isolamento & purificação , Serratia/isolamento & purificação , Bacillus/genética , DNA Bacteriano/genética , DNA Ribossômico/genética , Pichia/genética , /genética , /genética , Serratia/genéticaRESUMO
In the first part of this study, four isolates of the fungus Beauveria bassiana (Bals.) Vuillemin (LPP1, LPP2, CG05 and CG24) and one isolate of Metarhizium anisopliae (Metsch.) Sorokin (CG46) were tested against adult foragers of Atta sexdens rubropilosa. Ants were allowed to walk on filter paper discs, inside Petri dishes, previously impregnated with 1 ml of a conidia suspension (2 x 10(7) conidia ml(-1)), maintained at 80% RH and 26 degrees C for 24 h and subsequently, transferred to sterile Petri dishes, maintained at 23 degrees C, 80% RH, 24 h dark. The mean values of LT(50) for LPP2, LPP1, CG46, CG24 and CG05 were 3.5, 3.7, 3.8, 4.2 and 4.4 days, respectively. Control insects for all tests in this study showed less than 10% mortality. Experiments were carried out to test the toxicity of imidacloprid (IMI) to A. sexdens rubropilosa. Mortality was evaluated 10 days following a 24 h exposure to the insecticide. Percent mortality caused by 500, 200, 100 and 10 ppm IMI was 77.8, 56.7, 45.5 and 5.5 respectively. Insects treated with 10 ppm IMI were observed to have reduced locomotor activity 24 h after exposure to the insecticide. The LC(50) of IMI was 154.3 ppm. Subsequent tests were carried out to evaluate the combination of a sub-lethal dose of IMI (10 ppm) and infection by CG24 (1 x 10(7) conidia ml(-1)). Mortality due to fungal infection alone was 43.3%. Mortality of insects treated with IMI followed by exposure to the fungus was 64.3%. These results indicate that IMI significantly increases the susceptibility of ants to infection by B. bassiana CG24.
Assuntos
Formigas/crescimento & desenvolvimento , Beauveria/patogenicidade , Imidazóis/administração & dosagem , Inseticidas/administração & dosagem , Metarhizium/patogenicidade , Nitrocompostos/administração & dosagem , Controle Biológico de Vetores , Animais , Formigas/efeitos dos fármacos , Formigas/fisiologia , Neonicotinoides , Controle Biológico de Vetores/métodosRESUMO
We show for the first time that the ventral diverticulum of the mosquito gut (impermeable sugar storage organ) harbors microorganisms. The gut diverticulum from newly emerged and non-fed Aedes aegypti was dissected under aseptic conditions, homogenized and plated on BHI medium. Microbial isolates were identified by sequencing of 16S rDNA for bacteria and 28S rDNA for yeast. A direct DNA extraction from Ae. aegypti gut diverticulum was also performed. The bacterial isolates were: Bacillus sp., Bacillus subtilis and Serratia sp. The latter was the predominant bacteria found in our isolations. The yeast species identified was Pichia caribbica.
Assuntos
Aedes/microbiologia , Bacillus/isolamento & purificação , Trato Gastrointestinal/microbiologia , Pichia/isolamento & purificação , Serratia/isolamento & purificação , Animais , Bacillus/genética , DNA Bacteriano/genética , DNA Ribossômico/genética , Pichia/genética , RNA Ribossômico 16S/genética , RNA Ribossômico 28S/genética , Serratia/genéticaRESUMO
Fungus garden material from recently established Atta sexdens rubropilosa colonies (6-12 months old) was sampled to detect antibiotic producing microorganisms that inhibited the growth of pathogens of insects and of the fungus gardens but did not affect their mutualistic fungus. A bacterium with activity against the entomopathogenic fungus Beauveria bassiana was isolated from 56% of the gardens tested (n=57) and identified from its biochemical profile and from 16S and 23S ribosomal DNA sequences as a member of the genus Burkholderia. The ant-associated Burkholderia isolates secreted a potent, anti-fungal agent that inhibited germination of conidia of the entomopathogenic fungi B. bassiana, Metarhizium anisopliae, of the saprophytic Verticillium lecanii, and also of a specialist fungus garden Escovopsis weberi. Growth of the ant's mutualist fungus was unaffected.
