Background: In recent years, acetic acid bacteria have been shown to be frequently associated with insects, but knowledge on their biological role in the arthropod host is limited. The discovery that acetic acid bacteria of the genus Asaia are a main component of the microbiota of Anopheles stephensi makes this mosquito a useful model for studies on this novel group of symbionts. Here we present experimental results that provide a first evidence for a beneficial role of Asaia in An. stephensi. Results: Larvae of An. stephensi at different stages were treated with rifampicin, an antibiotic effective on wild-type Asaia spp., and the effects on the larval development were evaluated. Larvae treated with the antibiotic showed a delay in the development and an asynchrony in the appearance of later instars. In larvae treated with rifampicin, but supplemented with a rifampicin-resistant mutant strain of Asaia, larval development was comparable to that of control larvae not exposed to the antibiotic. Analysis of the bacterial diversity of the three mosquito populations confirmed that the level of Asaia was strongly decreased in the antibiotic-treated larvae, since the symbiont was not detectable by PCR-DGGE (denaturing gradient gel electrophoresis), while Asaia was consistently found in insects supplemented with rifampicin plus the antibiotic-resistant mutant in the diet, and in those not exposed to the antibiotic. Conclusions: The results here reported indicate that Asaia symbionts play a beneficial role in the normal development of An. stephensi larvae.
Bibliographical noteFunding Information:
This study was conceived thanks to the network established in the context of COST Action FA0701. Scientific missions of PhD stdudents and PostDocs involved in this study were also supported by this COST Action. The project was supported by the Firb-Ideas (grant RBID082MLZ) and Prin 2007 (grant 2007PK2HB7_002), both from the Italian Ministry of University and Research (MIUR), and by the EU-FP7 Capacities-Infrastructure 2008 (grant 228421) to G. F. The work has been also performed in the frame of the project BIODESERT (European Community’s Seventh Framework Programme CSA-SA REGPOT-2008-2 under grant agreement no 245746). CB and BC thank Massimo Pajoro for inspirations. This article has been published as part of BMC Microbiology Volume 11 Supplement 1, 2012: Arthropod symbioses: from fundamental studies to pest and disease mangement. The full contents of the supplement are available online at http://www.biomedcentral.com/1471-2180/12?issue=S1.
ASJC Scopus subject areas
- Microbiology (medical)