Inhibition Effect Of Jinggangmycin On The Reproduction Of The Small Brown Planthopper(SBPH),Laodelphax Striatellus(Fallén) And Its Mechanisms

The small brown planthopper(SBPH),Laodelphax striatellus(Fallen)is a devastating pest polyphagously feeding on various crops such as rice,wheat and corn in china agri-ecosystem where the antibiotic bactericide Jinggangmycin(JGM)is extensively employed against rice sheath blight(RSB)for its low toxicity,low residue and low cost.Temporally,the SBPH and RSB usually coincide amid rice growing stage.An interesting question arising from this scenario is how JGM affects the population of SBPH while controls the development of RSB.To investigate this,the proteomic analysis of JGM-treated insects versus control ones was performed to yield key proteins that were significantly down-regulated upon JGM treatment.This work aims to elucidate the underlying molecular mechanisms of JGM-suppressed SBPH fecundity and provide guidances for proper use of chemicals in paddy field.1.The proteomic analysis of JGM-treated vs control SBPHThe differentially expressed proteins of SBPH subjected to JGM spray compared to control SBPH were screened to reveal the molecular mechanisms underlying JGM-suppressed fecundity of Laodelphax striatellus.A total of 95 differentially expressed proteins(62 up-regulated,33 down-regulated)were identified in the JGM-treated group vs control group and corresponding bioinformations of these proteins were obtained by annotation and enrichment analysis.The significantly down-regulated glucose dehydrogenase(GDH),responsible for fatty acid and amino acid metabolism,was amenable to further gene function study.2.The effects of GDH knockdown on SBPH reproductive physiologyThe GDH full-length sequence was cloned and spliced based on the known sequence fragments.The artificial diet-mediated RNA interference was conducted to deliver the ds GDH and dsGFP into JGM-treated females.The present results showed the GDH transcript level of the JGM treated group was significantly lower than that of the control group,down by 72%;and the GDH transcript level of JGM+dsGDH group significantly reduced by 74%compared to the JGM treatment.More importantly,the JGM treatment and the JGM+dsGDH treatment significantly implicated the fecundity of Laodelphax striatellus females,registered as reduced egg-laying compared to control and JGM-treated group,down by 35.7%and 48.6%,respectively.In addition,apparent ripe oocytes were hardly observed in the ovaries of JGM-and JGM+dsGDH-treated females.Biochemical tests demonstrated that the total fat and fatty acid content as well as body weight of JGM and JGM+dsGDH treatments were significantly decreased than those of the control and JGM-treated group,respectively.