RT Journal Article
SR Electronic
T1 Larvicidal activity of the photosensitive insecticides, methylene blue and rose bengal, in <em>Aedes aegypti</em> and <em>Anopheles gambiae</em> mosquitoes
JF bioRxiv
FD Cold Spring Harbor Laboratory
SP 2023.06.30.547250
DO 10.1101/2023.06.30.547250
A1 Meier, Cole J.
A1 Hillyer, Julián F.
YR 2023
UL http://biorxiv.org/content/early/2023/07/01/2023.06.30.547250.abstract
AB BACKGROUND Insecticides are critical for controlling mosquito populations and mitigating the spread of vector–borne disease, but their overuse has selected for resistant populations. A promising alternative to classical chemical insecticides is photosensitive molecules—here called photosensitive insecticides or PSIs—that when ingested and activated by light, generate broadly toxic reactive oxygen species. This mechanism of indiscriminate oxidative damage decreases the likelihood that target site modification-based resistance evolves. Here, we tested whether the PSIs, methylene blue (MB) and rose bengal (RB), are viable insecticides across the mosquito lineage.RESULTS MB and RB are phototoxic to both Ae. aegypti and An. gambiae at micromolar concentrations, with greatest toxicity when larvae are incubated in the dark with the PSIs for 2 hr prior to photoactivation. MB is ten times more toxic than RB, and microscopy-based imaging suggests that this is because ingested MB escapes the larval gut and disperses throughout the hemocoel whereas RB remains confined to the gut. Adding food to the PSI-containing water has a bidirectional, concentration-dependent effect on PSI toxicity; toxicity increases at high concentrations but decreases at low concentrations. Finally, adding sand to the water increases the phototoxicity of RB to Aedes aegypti.CONCLUSION MB and RB are larvicidal via a light activated mechanism, and therefore, should be further investigated as an option for mosquito control.Competing Interest StatementThe authors have declared no competing interest.PSIPhotosensitive insecticideROSReactive oxygen speciesNTNo treatmentMBMethylene blueRBRose bengalAn. gambiaeAnopheles gambiaeAe. aegypti&gt;Aedes aegypti.