Control of Aedes aegypti (Diptera: Culicidae) by means of biofilm-forming actinobacteria.

Actinobacteria are a group of widely known microorganisms used in the synthesis of insecticidal bioactive compounds. Nevertheless, over-exploitation of Streptomyces-derived metabolites has led to explore new bioactive molecules based on non-streptomycetes actinobacteria in order to minimize the development of insecticide resistance in Aedes aegypti. In accordance with to the use of eco-friendly bioagents, in this study biofilm-forming actinobacteria were characterized on the basis of assessment their growth dynamics, larvicidal mortality and sublethal effects. Actinobacteria identification, biofilm growth and larvicidal bioactivities were performed by employing bacterial cultures, photomicrograph-based image analysis and bioassays. Results indicated that bacterial morphotypes belong to Pseudonocardiaceae (PsA1TA) and Corynebacteriaceae (CoA2CA), which showed a distinctly substrate-dependent growth. PsA1TA microcolonies were randomly distributed on abdominal and thoracic membranous epicuticle. Afterwards, the thickness of mono- and bi-layered biofilms were increased fourfold the larval thoracoabdominal width (infectious breadth, 1010 µm - 1036 µm). In contrast, cephalic and anal sclerotized structures were radially encased by CoA2CA biofilms and increased threefold the size of both structures (infectious breadth, 1820 - 2030 µm y 1650 - 1860 µm, respectively). Although biofilms caused dissimilar mortality rates on the four larval instars, PsA1TA exerted highest larvicidal activity and virulence on second instar larvae (58 %-96 hours, LT50: 3.4 days) y CoA2CA on fourth instar larvae (85 %-96 hours, LT50: 2.5 days). CoA2CA also induced incomplete release of pharate individuals as well as buckled protruding tarsi in newly emergent adults, whilst larval cadavers were overwhelmingly encased within massive biofilm aggregates. Biofilm-forming actinobacteria performed biolarvicidal activity and sublethal responses in A. aegypti.

Bibliographic Details

Main Authors:	Bobadilla Alvarez, Miguel Constante, Palomino Cadenas, Edwin Julio
Format:	Digital revista
Language:	spa
Published:	Universidad Nacional de Colombia - Sede Bogotá - Facultad de Ciencias - Departamento de Biología 2021
Online Access:	https://revistas.unal.edu.co/index.php/actabiol/article/view/86966
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