title: Larvicidal and Growth-Inhibitory Activity of Entomopathogenic Bacteria Culture Fluids Against Aedes aegypti (Diptera: Culicidae).
abstract: Dengue, Chikungunya, and Zika are important vector-borne diseases, and Aedes aegypti L. is their main transmitter. As the disease management is mainly based on mosquito control strategies, the search for alternative and cost-effective approaches is ongoing. The Gram-negative bacteria Xenorhabdus nematophila and Photorhabdus luminescens are symbiotically associated with entomopathogenic nematodes and are highly pathogenic for insect larvae. After we have recently confirmed the toxicity of these bacteria in Ae. aegypti larvae, we here evaluated the toxic activity of culture fluids on the development of this mosquito species. Larval susceptibility was assessed by exposing larvae to different concentrations of P. luminescens or X. nematophila culture fluids to confirm whether secondary metabolites might cause the mosquitos' death. Xenorhabdus nematophila culture fluid was more effective and stable during the mosquito pathogenicity bioassays compared to that of P. luminescens. Larval mortality started a few hours after exposure of the insects to the fluids. Furthermore, the residual effect of larvicidal activity of X. nematophila fluid persisted at full efficiency for 4 d. Particularly, larval mortality was still higher than 50% for up to 8 d. Exposure of larvae to a sublethal dose of X. nematophila fluid delayed pupation as well as emergence of adult mosquitoes and caused cumulative larval mortality higher than 90% by day 14. Here, we describe for the first time the use of stable culture fluids and therefore secondary metabolites of P. luminescens and X. nematophila as a promising basis for the use as biopesticide for control of Ae. aegypti in the future.
authors.affiliation: Departamento de Microbiologia, Imunologia e Parasitologia, Instituto de Ciências Básicas da Saúde, Universidade Federal do Rio Grande do Sul, Rua Sarmento Leite 500, 90050-170, Porto Alegre, Rio Grande do Sul, Brazil (onilda.silva@ufrgs.br).
authors.forename: João
authors.initials: J
authors.lastname: Luiz Rosa da Silva
authors.affiliation: Departamento de Microbiologia, Imunologia e Parasitologia, Instituto de Ciências Básicas da Saúde, Universidade Federal do Rio Grande do Sul, Rua Sarmento Leite 500, 90050-170, Porto Alegre, Rio Grande do Sul, Brazil (onilda.silva@ufrgs.br).
authors.forename: Fernanda
authors.initials: F
authors.lastname: Undurraga Schwalm
authors.affiliation: Departamento de Microbiologia, Imunologia e Parasitologia, Instituto de Ciências Básicas da Saúde, Universidade Federal do Rio Grande do Sul, Rua Sarmento Leite 500, 90050-170, Porto Alegre, Rio Grande do Sul, Brazil (onilda.silva@ufrgs.br).
authors.forename: Carlos
authors.initials: C
authors.lastname: Eugênio Silva
authors.affiliation: Departamento de Microbiologia, Imunologia e Parasitologia, Instituto de Ciências Básicas da Saúde, Universidade Federal do Rio Grande do Sul, Rua Sarmento Leite 500, 90050-170, Porto Alegre, Rio Grande do Sul, Brazil (onilda.silva@ufrgs.br).
authors.forename: Marisa
authors.initials: M
authors.lastname: da Costa
authors.affiliation: Biozentrum, Bereich Mikrobiologie, Ludwig-Maximilians-Universität München, Großhaderner Str. 2-4, 82152 Martinsried/München, Germany (ralf.heermann@lrz.uni-muenchen.de).
authors.forename: Ralf
authors.initials: R
authors.lastname: Heermann
authors.affiliation: Departamento de Microbiologia, Imunologia e Parasitologia, Instituto de Ciências Básicas da Saúde, Universidade Federal do Rio Grande do Sul, Rua Sarmento Leite 500, 90050-170, Porto Alegre, Rio Grande do Sul, Brazil (onilda.silva@ufrgs.br).
authors.forename: Onilda
authors.initials: O
authors.lastname: Santos da Silva
mesh_terms: D000330:Aedes / Q000254:growth & development / Q000382:microbiology*; D000818:Animals; D007814:Larva / Q000254:growth & development / Q000382:microbiology; D009032:Mosquito Control; D010572:Pest Control, Biological; D020637:Photorhabdus / Q000502:physiology*; D020593:Xenorhabdus / Q000502:physiology*
keywords: Photorhabdus luminescens; Xenorhabdus nematophila; biopesticide; larvicidal activity; mosquito