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C J Howell

Publications and source records attributed to C J Howell.

24 records · Page 2Linked to original sources

[Tick resistance to pesticides in the R.S.A. - some observations (author's transl)].

Observations on the screening for resistance against acaricides in both larvae and adults of tick species commonly found on cattly in South Africa, have shown that widespread resistance of varying degrees occurs in strains of all these species against compounds of the arsenical, organochlorine and organophosphorous groups. With few exceptions the degree of resistance is of a low order and probably indicative of selection at the low acaricide concentrations generally used by stockowners. The distribution of less susceptible and resistant strains is patchy, and fully susceptible strains are found in the same areas.

Animals↗

Some toxic, physical and chemical properties of the oral secretion of the sand tampan, Ornithodoros savignyl Audouin (1827).

Mice, exposed to the effects of the oral secretion of Ornithodorus savignyi by injection, revealed that a potent toxin is present in the secretion. Electrophoretic and chromatographic separations of the secretion showed a heterogeneous pattern of protein-like substances. Toxicity trials on these fractions showed that the toxic principle is protein in nature and fairly heat stable.

Amino Acids↗