title: [Studies of the time of effectiveness and the characterization of compounds in insecticide tests with Aedes aegypti].
abstract: The contact-toxicity of 5 insecticides (2 chlorinated hydrocarbons, 2 organophosphate compounds 1 P-substance) are tested against Aedes aegypti L (adults). Because of the relationship between dosage (quantity of application) and time of effectiveness of a compound, we are able to design a specific curve of time-efficacy of each insecticide at graded intervals (= increasing dilutions). This curve may be characteristic of different pure compounds--possibly in connection with other features. The time measurement as a quantitative response was chosen according to the directions of Finney 1952 (mean time to response--dosage). The simple statistical analysis was possible after continuous observation until response-metameter as criterion for time of bioassay = time of exposure. Transformation into complete records (Finney) in feasible with a long period of observation, corresponding response-metameter, extreme values etc. This was found to be the only way to obtain a statistical analysis without complications, and only a few parameters in this model. For statistical evaluation of the differences of the mean reaction times for each dilution of DDT, gamma-BHC, Methylparathion and Trichlorofon the U-test according to Mann & Whitney has been applied. Percentages of 'inactivity' at each dilution are added (decreasing from D7). --The curve of time--efficacy is described, and the possibilities of characterization and indentification of the compounds discussed. General features of ET 50 values and mean reaction times are pointed out, and also the relation of time to response (= exposure time) and dosage, expressed by a simple hyperbolic equation (Haber's formula). The uptake of insecticides by "self-dosine" of insects (as practised in this bioassay) is the closest approximation to natural conditions, but the real dose is unknown [and will depend on the physiological condition of the insects]. Some values with Aedes aegypti (whole activity of the pure compound of each test object labelled with radioactive Trichlorfon) are added (exposure on 1 per cent deposite of insecticide).
mesh_terms: D000330:Aedes; D003634:DDT; D001556:Hexachlorocyclohexane; D007306:Insecticides / Q000032:analysis; D010278:Parathion; D013995:Time
chemical_list: D007306:Insecticides; D001556:Hexachlorocyclohexane; D010278:Parathion; D003634:DDT
vernacular_title: Wirkungszeit-Ermittlungen und Wirkstoff-Charakterisierung bei Insektizidtestungen mit Aedes aegypti