How can mosquitoes develop and reproduce in the complete absence of juvenile hormone?

PROJECT SUMMARY Recent dramatic increases in the incidence of mosquito-borne diseases, like Malaria, Zika, Chikungunya and Dengue Fever, and the wide-spread resistance of mosquitoes to insecticides emphasizes the need for new approaches for insect control based on mosquito-specific agents. The discovery of such mosquito-specific control agents depends on continued basic research on the biology of mosquitoes. Juvenile hormone (JH), an epoxidated sesquiterpenoid, is an essential regulator of major developmental and life history events in insects. Insects and crustaceans originated from aquatic pancrustacean ancestors that invaded terrestrial ecosystems over 450 million years ago. The Methoprene-tolerant (Met) protein is the intracellular receptor for insect JHs. The ability of Met to respond to MF, the “crustacean JH”, suggests that the role of Met in sesquiterpenoid signaling precedes the evolutionary separation of the hexapoda from the crustacean lineages. To address the evolutionary and biological significance of MF epoxidation, we generated mosquitoes completely lacking either of the two enzymes that catalyze the last steps of MF/JH biosynthesis and epoxidation, the methyl transferase (JHAMT) and the P450 epoxidase CYP15 (EPOX). jhamt-/- larvae lacking both MF and JH died at the onset of metamorphosis. While epox-/- mutants, which synthesized MF but no JH completed the entire life cycle. While epox-/- adults are fertile, the reproductive performance of both sexes is dramatically reduced. Using these two lines of null mutant mosquitoes, we will investigate how in the absence of JH, MF is sufficient to complete adult development. Our hypothesis is MF is able to properly activate the gene networks that control mosquito larval development and metamorphosis. Additionally, we will investigate the reproductive fitness cost in JH null females. We expect to recognize the molecular mechanism underlying the differences in JH signaling in our three model lines (jhamt-/-, epox-/- and WT). Our two null mutant mosquito lines provide a unique opportunity to explore the role of non-epoxidated versus epoxidated JHs in the development and reproduction of insects. Completing the proposed research could lead to the identification of targets for designing new, specific and affordable strategies suitable for mosquito control.