An evaluation by bioassay of the persistence of DDT deposits on riverine vegetation in the Northern Guinea Savannah vegetation Zone of Nigeria and observations on the factors influencing the availability of deposits to Glossina palpalis (R.-D.)

Publisher： Cambridge University Press

E-ISSN： 1475-2670|54|3|497-508

ISSN： 0007-4853

Source： Bulletin of Entomological Research, Vol.54, Iss.3, 1963-11, pp. : 497-508

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Abstract

The persistence of DDT deposits, derived from dilutions of an emulsion concentrate, Arkotine D.25, on the leaves of riverine vegetation in the Northern Guinea Savannah vegetation zone of Nigeria was studied in the laboratory by a bioassay method using teneral females of Glossina palpalis (R.-D.) as test insects. Irrespective of whether sprayed in the dry or wet season, deposits derived from sprays containing 5.0 per cent. DDT produced by the Warley knapsack sprayer were still reasonably toxic one year after spraying. Deposits derived from sprays having a concentration of DDT varying from 1·25 to 5·0 per cent. DDT were equally toxic when young, but those from the lower concentrations were weathered much more rapidly than those from the 5·0 per cent, sprays. Young deposits produced by Warley and Motoblo sprayers were equally toxic, but deposits from the Motoblo deteriorated more rapidly than those of the Warley.