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R ELLIOTT

Publications and source records attributed to R ELLIOTT.

At least 19 recordsLinked to original sources
PubMed1964

STUDIES ON THE KINETIC RESPONSE OF MOSQUITOS TO CHEMICALS.

An apparatus is described for study of the activity of mosquitos either with or without stimulation by exposure to insecticides or other chemicals such as repellents. Batches of up to 30 mosquitos can be used and they can be studied for a longer time than is possible with, for instance, the method put forward in 1960 by the WHO Expert Committee on Insecticides. Random activity by the test insects, in the absence of directional stimuli due to light or chemicals, is converted to progress through baffles in the partitions separating a series of four boxes and is expressed as a percentage of the total possible activity that would be shown if all the insects passed all the baffles. Exposure to chemicals, by exposure to impregnated papers, can take place before the mosquitos are put in the apparatus, or in the first box. In the experiments described, the activity of recently fed female Anopheles was studied over periods of up to 20 hours.Comparison of the method described with other methods shows that it shares the high variance characteristic of all current procedures for studying mosquito behaviour, although the use of large numbers of insects over long periods has some advantages. The method does, however, give information on mortality under conditions of facultative contact that may be a valuable supplement to the results of conventional susceptibility tests.

Animals↗
PubMed1959

Insecticide resistance in populations of Anopheles gambiae in West Africa.

A method published by Elliott in 1958 for investigation of insecticide resistance in Anopheles larvae has been applied to strains of A. gambiae from various parts of West Africa, and the results analysed to provide information as to the proportions of the three possible genotypes in the different populations.At Kano, the gene conferring resistance to dieldrin and gamma-BHC appears to be increasing in the wild population, being present in about 50% and 42% of the population in the homozygous (RR) and heterozygous (RS) states respectively. Theoretical considerations suggest that in a situation where the male heterozygote is sterile, the gene in the minority will tend to become extinct in the absence of any specific selection. In a colony maintained in captivity for six generations without intentional selection the reverse was seen to happen, the S gene increasing its representation at the expense of the R gene.In Sokoto Province, some figures of the same type were obtained; these are analysed and found to produce results compatible with those from Kano, especially as regards the LC(50) level derived for the effect of gamma-BHC on the RS fraction of the population.At Freetown, a similar analysis suggests that the factor conferring resistance to gamma-BHC has also appeared. About 66% of the sample examined appear to carry the R gene.At Ibadan, samples of the population showed some tolerance to dieldrin, but the presence of the specific type of resistance seen elsewhere was not established. The tolerance appears to be non-specific, as some relative tolerance to DDT appeared to be present also.

Africa, Western↗