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K S HOCKING

Publications and source records attributed to K S HOCKING.

6 recordsLinked to original sources
PubMed1964

ASSESSMENT OF THE KILL OF ANOPHELES GAMBIAE BY THE FUMIGANT INSECTICIDE DICHLORVOS IN EXPERIMENTAL HUTS.

As part of the World Health Organization's programme for the evaluation and testing of new insecticides, different types of dichlorvos dispenser were installed in experimental huts in Tanganyika for study of their effectiveness in killing Anopheles gambiae. It was found that satisfactorily high mosquito mortalities of 75% or more were maintained for one to two months after installation of a dispenser. Mortalities were about 10% higher in huts with grass roofs than in those with mud-lined roofs. The vapour toxicity was similar in the two types of hut, but the results of bio-assay tests on different types of surface showed that there was a residual contact effect of the insecticide as well as the fumigant effect; the lower mortalities in the mud-roofed huts may be due in part to removal or decomposition of the dichlorvos by the mud surface.Measurements of blood pseudo-cholinesterase levels in persons who slept in the experimental huts gave no indication that the dichlorvos had any harmful effect on them.

Animals↗
PubMed1963

Tsetse-fly control and eradication.

In many instances the cheapest and quickest way of controlling trypanosomiasis is to reduce the number of vectors and the opportunities for contact between man and vector. For permanent results, moreover, eradication of the vectors is necessary, since eradication of trypanosomiasis by chemotherapeutic means has so far not proved feasible.For a variety of reasons, game destruction as a method of fly control is gradually being replaced by other methods. Of these, the complete removal of bush cover will always effectively eradicate tsetse flies, but in order to save time, labour and money, partial clearing (selective or discriminative) is more usually resorted to. Provided this is preceded by extensive and accurate surveys of fly infestation, it is generally successful.Blanket applications of insecticides from aircraft or from ground aerosol machines can give good and rapid results; however, as knowledge of the habits and behaviour of Glossina species grows, the discriminative application of insecticides can be made more precise, economical and effective. This method of using the residual insecticides seems to be the most promising for the future.

Aerosols↗
PubMed1962

Assessment of the residual toxicity to Anopheles gambiae of the organophosphorus insecticides Malathion and Baytex.

As part of a WHO programme to evaluate possible substitutes for the chlorinated hydrocarbons to which anopheline mosquitos in many countries have become resistant, two organophosphorus insecticides, malathion and Baytex, were tested as residual sprays on various types of surface against Anopheles gambiae adults in experimental huts at Magugu in Tanganyika. The long-lasting toxicity of both insecticides on relatively impervious surfaces was confirmed, but-as is the case with the chlorinated hydrocarbons-shorter persistence was obtained on sorptive surfaces. As most of the mosquitos rested on the roof, its surface was of much greater importance than the wall surface in determining kill; trials with naturally entering mosquitos indicated that where the roof was of grass malathion was to be preferred to Baytex. Observations confirmed that control huts attracted far more mosquitos than the treated huts and that the insecticide vapour apparently masked the human odour.

Animals↗
PubMed1960

Gamma-BHC/cereclor-a new, long-acting lindane formulation for malaria control.

Sorption of insecticides by muds and other materials used in the construction of native huts prolongs their duration of action or persistence. The use of gamma-BHC as a residual insecticide has been limited by the fact that its sorption by most materials is of a low order, so that it is comparatively short acting. If gamma-BHC is melted with a resin, the solid solution can be converted into a water-dispersible powder which is much more persistent on sorptive and semi-sorptive surfaces. Laboratory experiments had shown that the best results were obtained with a proprietary resin known as Cereclor. Field trials conducted by the authors have now demonstrated that this formulation retained its efficacy for at least six months, even on surfaces of low sorptive power, such as thatch and sisal. Gamma-BHC alone was much less persistent, except on mud walls, but even here bioassay showed the formulation with Cereclor to be more active. The authors consider that gamma-BHC/Cereclor approximates to the ideal insecticide for the spraying of native huts in malaria control.

Animals↗