**5. Conclusions**

An approach has been demonstrated by this study for establishing a suitable method for screening for resistance to a non-contact insecticide.

A discriminating, or diagnostic concentration for topically applied dinotefuran, has been proposed and should now be validated against field mosquito populations where ATSBs are under evaluation. Validation with other ingested insecticides is recommended as further ATSB or similar products are developed.

**Supplementary Materials:** The following supporting information can be downloaded at: https: //www.mdpi.com/article/10.3390/insects13040311/s1, File S1: All raw data.

**Author Contributions:** Conceptualization, R.S.L. and J.V.; methodology, G.J.I.P., S.B., R.S.L. and J.V.; formal analysis, G.J.I.P.; investigation, G.J.I.P. and S.B.; data curation, G.J.I.P.; writing—original draft preparation, G.J.I.P. and R.S.L.; writing—review and editing, J.V. and S.B.; visualization, G.J.I.P.; supervision, R.S.L. and J.V. All authors have read and agreed to the published version of the manuscript.

**Funding:** This work was funded by the innovative vector control consortium (IVCC), who are supported by the Bill and Melinda Gates Foundation, under grant number OPP1148615.

**Data Availability Statement:** All raw data can be found in the Supplementary Materials.

**Acknowledgments:** The authors would like to thank Helen Williams, Amy Guy, and members of Liverpool Insect Testing Establishment (LITE) team for rearing all mosquitoes at the Liverpool School of Tropical Medicine (LSTM). Also, Julian Entwistle, consultant to IVCC, for his support of the project and useful input into preparation of this publication.

**Conflicts of Interest:** The authors declare no conflict of interest.

#### **Appendix A. Quantifying the Average Size of a Sugar Meal Using Fluorescein Sodium Salt (Uranine)**

## *Appendix A.1. Introduction*

To provide an estimate on the dose of insecticide taken up by mosquitoes to insecticide in ingestion assays, it is important to know the approximate size of a sugar meal taken in an environment comparative to the ingestion assays.