Farmers’ pesticide usage practices in the malaria endemic region of North-Western Tanzania: implications to the control of malaria vectors
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Date
2019-11
Journal Title
Journal ISSN
Volume Title
Publisher
BioMed Central (BMC)
Abstract
Background: Pesticides remain the mainstay for the control of agricultural pests and disease vectors. However,
their indiscriminate use in agriculture has led to development of resistance to both crop pests and disease vectors.
This threatens to undermine the success gained through the implementation of chemical based vector control
programs. We investigated the practices of farmers with regard to pesticide usage in the vegetable growing areas
and their impact on susceptibility status of An. gambiae s.l.
Methods: A stratified multistage sampling technique using the administrative structure of the Tanzanian districts as
sampling frame was used. Wards, villages and then participants with farms where pesticides are applied were
purposively recruited at different stages of the process, 100 participants were enrolled in the study. The same
villages were used for mosquito larvae sampling from the farms and the surveys were complimented by the
entomological study. Larvae were reared in the insectary and the emerging 2–3 days old female adults of Anopheles
gambiae s.l were subjected to susceptibility test.
Results: Forty eight pesticides of different formulations were used for control of crop and Livestock pests.
Pyrethroids were the mostly used class of pesticides (50%) while organophosphates and carbamates were of
secondary importance. Over 80% of all farmers applied pesticides in mixed form. Susceptibility test results
confirmed high phenotypic resistance among An. gambiae populations against DDT and the pyrethroids
(Permethrin-0.75%, Cyfluthrin-0.15%, Deltametrin-0.05% and Lambdacyhalothrin-0.05%) with mortality rates 54, 61,
76 and 71%, respectively. Molecular analysis showed An. arabiensis as a dominant species (86%) while An. gambiae
s.s constituted only 6%. The kdr genes were not detected in all of the specimens that survived insecticide
exposures.
Conclusion: The study found out that there is a common use of pyrethroids in farms, Livestocks as well as in
public health. The study also reports high phenotypic resistance among An. gambiae s.l against most of the
pyrethroids tested. The preponderance of pyrethroids in agriculture is of public health concern because this is the
class of insecticides widely used in vector control programs and this calls for combined integrated pest and vector
management (IPVM).
Description
Keywords
Pesticides, Insecticides, Malaria vectors, Farmers, Resistance, Magu