In-depth physiological study on the sustainable application of a botanical insecticide with low mammalian toxicity against Aedes aegypti (Diptera: Culicidae)

Abstract

Research into the exploration of bioactive insecticides as an alternative to synthetic compounds has garnered increasing attention, particularly in the context of sustainable pest management. In this study, a two-sex life table was constructed based on the Waco strain to determine whether the prolonged larval period in haedoxan A-resistant (HAR) strain Aedes aegypti is related to ecdysone-regulated development. The effect of ecdysone on the sensitivity of the 3rd-instar larvae to HA was investigated, along with the determination of 20-hydroxyecdysone (20E) content in A. aegypti. The results showed that the 20E content in larvae from HAR strain was significantly lower than that of Waco strain. And, the sensitivity of larvae treated with ecdysone to HA was increased. Two-sex life table results indicated that ecdysone can accelerate the growth and development of larvae, however, it also shortened the life span of adult mosquitoes and reduced reproduction rate. Notably, cytotoxic activity against human normal liver cell L02 demonstrated that HA was less toxic and did not cause intracellular oxidative stress compared to permethrin. Overall, these findings contribute to a deeper understanding of the mechanisms by which the larval period of A. aegypti is prolonged under HA selection. Furthermore, our results provide valuable insights for the application of HA as an effective botanical insecticide.