The Function And Regulation Mechanisms Of Juvenile Hormone And The Receptor Gene Methoprene-Tolerant (Met) During Flight Optimizing Reproduction Of Mythimna Separata (Walker)

Mythimna separata(Walker)is a typical migratory agricultural pest,and its migration has led to a decline in the production of large-area food crops in China.Previous studies have determined the flight pattern that promotes M.separata reproduction,but its intrinsic regulatory mechanisms are not clear.We have shown that Juvenile hormone(JH)is closely related to the flight and reproduction of M.separata.Methoprene-tolerant(Met),a member of the bHLH-PAS(helix–loop–helix-Per-ARNT-Sim)transcription factor family,is a receptor for JH in insects such as locusts,which regulates the signaling process of reproduction in JH.It has a very important role.Therefore,studying the function of JH and the receptor gene Met in flight-induced reproductive migratory mode is a key link in the mechanism of migratory worm migration.In order to verify the function and regulatory mechanisms of JH and gene Met in M.separata reproduction and flight-promoting reproduction,we use RT-QPCR,RNAi and flying technology to study the titer changes of JH in the flight modes of promoting and inhibiting reproduction,and to determine Kr-h1 gene and Vg gene expression,ovarian development and reproductive behavior of M.separata after the suspension of only Met gene,silencing Met gene binding JHA,silencing Met gene binding flight treatment.The main results are as follows:1.The study confirmed the function of JH in M.separata in flight regulation of reproduction.After flight 2 nights,the JHI and JHII titers increased prematurely compared to the control and were significantly higher than the control M.separata after 3 days of age.The JHI and JH II titers of the M.separata that had been flying for 5 nights were significantly lower than the control M.separata at the fourth night of flight.The research has confirmed that JH plays an important role in flight promotion of reproduction.2.The study confirmed the function of Met in the reproductive process of M.separata.Interfering with the Met gene in the ovary of the M.separata hindered the expression of the kr-h1,Vg gene and ovarian development,thereby inhibiting the reproduction of the M.separata.The results indicated that Met gene was involved in the regulation of the reproduction of M.separata,and plays an important role in the expression of kr-h1,Vg gene and ovarian development.3.Using RNA interference combined with drip JHA to clarify the function of Met gene in JH regulation of reproductive signaling.application of JHA on day1 did not rescue the normal expression of kr-h1,Vg gene and ovarian development in the Met RNAi M.separata.In addition,the reproduction of M.separata was still significantly inhibited.The results showed that JH could not play a role in promoting reproduction when the Met gene was deleted,which proved that Met should be a key receptor on the JH signaling pathway of the M.separata.JH can promote Vg deposition and accelerate ovarian development and reproduction by binding to the receptor Met in the M.separata.4.Using RNA interference combined with flight treatment clarified the function of Met gene in the flight of M.separata.to promote reproduction.After 2 nights flight,the kr-h1、Vg gene expression and ovarian development were promoted in M.separata without silencing Met gene,which accelerated the spawning;Silencing the Met gene of M.separata combined with 2 nights flight not onlyresulted in a significant reduction of the kr-h1 、 Vg gene mRNA expression levels,but also blockd ovarian development,thus inhibiting reproduction.The results not only proved the important role of Met gene in flight to promote reproduction,but also further improved the molecular regulation mechanism of JH in the downstream of flight to promote reproduction of M.separata.