title: An evaluation of the residual lifespan of DDT in malaria control.
abstract: The insecticide lifespan of DDT was assessed in huts sprayed for malaria control. The age of the spray deposits ranged from 3 up to 22 months. Blood-fed female Anopheles arabiensis were either released into the huts or exposed on sprayed surfaces by a bioassay technique. Mosquitoes released were recovered in exit traps fitted on windows or dead on the floor. Only 50% or less of mosquitoes released in sprayed huts were recovered. Mortality figures for recovered mosquitoes ranged from 94% at 3 months, declining to 19% for huts sprayed 18 months previously. Of the recovered mosquitoes, 60% or more attempted to escape from sprayed huts within two hours postrelease up to 15 months postspray. Bioassays gave average mortalities of 95 and 76% on thatch and mud walls, respectively. Analysis of mud samples from test huts showed that target dose of 2 g AI/m2 of DDT was not being achieved. The results support the need for an annual spraying cycle.
authors.affiliation: Blair Research Laboratory, Causeway, Harare, Zimbabwe.
authors.forename: S M
authors.initials: SM
authors.lastname: Mpofu
authors.forename: P
authors.initials: P
authors.lastname: Taylor
authors.forename: J
authors.initials: J
authors.lastname: Govere
mesh_terms: D000818:Animals; D000852:Anopheles; D001681:Biological Assay; D003634:DDT / Q000032:analysis*; D005260:Female; D006801:Humans; D007303:Insect Vectors; D008288:Malaria / Q000517:prevention & control*; D009032:Mosquito Control / Q000379:methods*; D010573:Pesticide Residues / Q000032:analysis*; D013997:Time Factors
chemical_list: D010573:Pesticide Residues; D003634:DDT