Journal of Vector Ecology (1996) 21, 26-30

M. Beck, M. Ludwig and N. Becker (1996)
Impact of microorganisms and water quality on the efficacy of Bacillus sphaericus Neide against Culex pipiens larvae in the laboratory
Journal of Vector Ecology 21 (1), 26-30
Abstract: The influence of water quality on the efficacy of Bacillus sphaericus against Culex pipiens larvae was investigated. Bioassays were conducted with different dilutions of a filtrate of hay-infusion. Impact of microorganisms in the filtrate on mosquito larval mortality was studied by comparison of bioassays and spore counts in sterilized and nonsterilized filtrates of hay-infusion. Increasing concentrations of the hay-infusion filtrate (0, 1, 10, 100%) resulted in higher LC₅₀ and LC₉₀ values. There were significant differences between larval mortalities in distilled water and hay-infusion concentrations, resulting in to 5-fold higher LC₅₀ and LC₉₀ values in 1 to 100 % hay-infusion. A linear relationship was observed between the organic content of the various dilutions of the filtrate and the efficacy of B. sphaericus. The presence of microorganisms resulted in a 2.7-fold increase in the LC₉₀ values of a hay-infusion filtrate compared to a sterilized hay-infusion filtrate at the beginning of the test. Seven days later the increase was as much as five times. There was a significantly higher efficacy of B. sphaericus in the sterilized hay-infusion seven days after incubation, which was not observed with the nonsterilized hay-infusion.
(The abstract is excluded from the Creative Commons licence and has been copied with permission by the publisher.)
Database assignments for author(s): Norbert Becker

Research topic(s) for pests/diseases/weeds:
biocontrol - natural enemies
environment - cropping system/rotation
Research topic(s) for beneficials or antagonists:
environment/habitat manipulation

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Pest and/or beneficial records:

Beneficial	Pest/Disease/Weed	Crop/Product	Country	Quarant.
	Culex pipiens
Lysinibacillus sphaericus (entomopathogen)	Culex pipiens