**5. Conclusions**

Large variation was found in the amount of fluorescein and insecticide applied when following WHO guidelines for manual spraying by well-trained spray operators. When comparing the automated track sprayer to standard manual spraying, variation in application rates were significantly reduced in all instances, indicating that a large proportion of the variation in spray application can be eliminated by automating the spraying procedure.

**Author Contributions:** Conceptualization, J.S., R.S.L., D.J.M. and M.J.K.; methodology, J.S., R.S.L., D.J.M. and M.J.K.; formal analysis, J.S., K.J.W. and G.M.F.; investigation, R.S.L., J.S., K.J.W., G.M.F., B.J.M. and M.J.K.; resources, F.W.M. and M.W.R.; data curation, J.S., K.J.W. and R.S.L.; writing— original draft preparation, J.S., R.S.L. and G.M.F.; visualization, J.S. and G.M.F.; supervision, R.S.L., B.J.M. and J.S.; manuscript revision and interpretation, M.W.R.; funding acquisition, D.J.M. and F.W.M. All authors have read and agreed to the published version of the manuscript.

**Funding:** This study was funded by the Bill and Melinda Gates Foundation (grant no. OPP1148615) https://www.gatesfoundation.org/ (accessed on 21 April 2022) through the Innovative Vector Control Consortium. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.

**Institutional Review Board Statement:** This study was part of a larger programme of research with the Innovative Vector Control Consortium (IVCC), which was reviewed and approved by the National joint board of Ethics in Tanzania, comprising the Medical Research Coordinating Committee and the Ministry of Health, Community Development, Gender, Elderly, & Children; certificate number NIMR/HQ/R.8a/Vol. IX/1646. No human participants or animals were included in this study.

**Informed Consent Statement:** Not applicable.

**Data Availability Statement:** The dataset generated and analysed during this study is available from the corresponding author upon reasonable request.

**Acknowledgments:** The authors would like to thank all colleagues at the KCMUCo-PAMVERC Test Facility for their support with the conduct of the study. We are also grateful to Graham Small, Derric Nimmo, Angus Spiers, John Clayton, and Jane Bonds for their helpful comments on the manuscript.

**Conflicts of Interest:** The authors declare no conflict of interest. The funders had no role in the design of the study; in the collection, analyses, or interpretation of data; in the writing of the manuscript, or in the decision to publish the results.
