Morin hydrate reduces survival and fertility, delays development and weakens lipid reserves in <i>Aedes aegypti</i>

The Aedes aegypti mosquito is generally associated with arboviruses that cause yellow fever, dengue, zika and chikungunya. The most efficient way to control their populations is through application in breeding sites of highly toxic insecticides that can also impact non-target organisms and generate resistant populations. Therefore, the use of compounds is desirable. Morin hydrate has broad pharmacological applications based on its antioxidant potential, in addition to not having negative effects on mammals. Therefore, the objective of the present study was to investigate the effects of morin hydrate on A. aegypti survival, pupation rate, egg laying, triacylglycerol reserves and expression of proteins related to lipid metabolism 24 h after exposure of larvae. For this, rearing media containing A. aegypti larvae with different concentrations of morin hydrate were formulated to evaluate the lethal concentration. Calculation of the expected lethal concentrations showed LC₂₅ of 52.692 μM, LC₄₀ of 111.121 μM, LC₅₀ of 174.775 μM, LC₇₅ of 575.083 μM and LC₉₀ of 1685.936 μM. Twenty-four hours after treatment with morin hydrate, surviving larvae were transferred to morin-free water with food, and their pupation rate and fertility were evaluated. We observed that an increase in the concentration of morin hydrate induced a dose-dependent reduction in survival, doubled pupation time in survivors and reduced the number of eggs laid by treated females during the larval stage by approximately 30% at concentrations exceeding 100 μM. From this, the impact of 24 h on the triacylglycerol (TAG) stock was evaluated, in addition to evaluating the expression of proteins involved in lipid metabolism. Larvae 24 h after treatment with 100 μM morin showed a reduction in TAG reserves of approximately 17%, while at 175 μM, there was a reduction of more than 33% in stocks, and at 500 μM there was a reduction of 61%. Furthermore, the lipolytic proteins TAGL1 and HSL were upregulated, while the lipogenic proteins FAS1, DGAT1 and GPAT1 were downregulated. Insulin-like receptors were also downregulated, unlike AKHr, which was also upregulated. These data demonstrate that morin hydrate reduces the survival and fertility of A. aegypti by affecting its lipid metabolism. Morin hydrate did not exhibit toxicity toward non-target organisms, demonstrating interesting potential for the control of mosquito populations.