Spickett, Arthur M.Van Ark, H.Verwoerd, Daniel Wynand2014-09-012014-09-0120131990Spickett, AM & Van Ark, H 1990, 'Fitting the Gompertz function to dose-response data of larval tick populations’, Onderstepoort Journal of Veterinary Research, vol. 57, no. 2, pp. 115-118.0330-2465http://hdl.handle.net/2263/41877The articles have been scanned in colour with a HP Scanjet 5590; 600dpi. Adobe Acrobat XI Pro was used to OCR the text and also for the merging and conversion to the final presentation PDF-format.Samples of 6, 1st generation larval populations of Boophilus decoloratus, originating from field collected females, were subjected to increasing doses of the organophosphate acaricide, Dioxathion. The dose-response relationship for 3 populations showed random heterogeneity, where systematic deviations from the linear probit lines were observed for the other 3 populations. Logistic and Gompertz regressions were also fitted for all 6 populations. Probit regressions fitted best for 2 populations exhibiting heterogeneous responses. The logistic regression fitted best for 1 population with heterogeneous responses and 1 population with systematic deviating responses. The Gompertz regression fitted best for the 2 remaining populations exhibiting systematic deviating responses. The Gompertz function may be useful in describing the dose-response relationship obtained for certain acaricidal toxicity tests.en©South Africa. Dept. of Agricultural Technical Services. ©University of Pretoria. Dept. of Library Services (digital).Veterinary medicineVeterinary medicine -- South AfricaArticle