Study On Physiology And Biochemistyry And Molecular Mechanisms Of Stimulation Of Reproduction Of The Small Brown Planthopper And The Brown Planthopper Induced By Two Pesticides

The small brown planthopper(SBPH),Laodelphax striatellus(Fallen)and the brown planthopper(BPH),Nilaparvata lugens(Stal)(Hemiptera:Delphacidae)are two destructive insect pests that can cause serious damage to rice crops via sap-sucking as well as virus-transmission,which result in devastating yield losses throughout Asian rice growing regions.Triazophos(TZP)is a typical insecticide that can induce resurgence of several insect pests according to previous studies.Jinggangmycin(JGM)has widely been applied as an antibiotic fungicide for controlling rice sheath blight.Due to the advantages of low toxicity,easy degradation and cost-saving,JGM is usually overused.Based on the finding that JGM and TZP stimulate reproduction of BPH and WBPH,this paper made an attempt to elucidate the mechanism of stimulation of reproduction induced by the two pesticides.1.Proteomic analysis of triazophos-treated SBPHTo ascertain mechanisms underlying the TZP-induced stimulation of reproduction,we performed proteomic analysis of TZP-treated SBPH using iTRAQ technique.A total of 6198 proteins were identified,of which 217 proteins were deferentially expressed relative to controls,with 56 up-regulated and 161 down-regulated.In addition,18 reproduction-related pathways from 118 pathways were subjected to pathway annotation and enrichment analysis.The substantially up-regulated long-chain fatty acid coenzyme A ligase(FACL)was screened for RNAi to further unravel its role in pesticide-induced stimulation of reproduction.2.The effects of silenced FACL on fecundity of SBPHThe full length cDNA of FACL was first cloned and then the SBPHs were reared by dsFACL artificial diet after TZP spray treatment.The feeding-based RNAi experiment demonstrated that the fecundity of TZP+dsFACL females was significantly reduced,the eggs laid per female decreased by 73.9%,the oviposition period decreased by 8.9 days and female longevity down by 7.9 days compared to controls.TZP+dsFACL influenced several physiological indexes,which protein content decreased by 4.7%,glycerin content down by 19.9%and body weight reduced by 13.6%,while no significant difference was found in crude fat content in relation with controls.We thereby speculated that FACL may be the potential target gene in TZP-induced stimulation of reproduction of SBPH.3、The change in oocyte development of JGM-treated BPH was observed by transmission electron microscopyPrevious studies mainly focused on insecticide-induced stimulation of reproduction of BPH.However,effect of insecticides on the growth and development of oocytes were neglected.In this paper,changes in oocytes and levels of hormones(juvenile hormone(JH)and 20-hydroxy ecdysone(20E))were observed by transmission electron microscopy(TEM).Results showed that the size of lipid droplets in oocytes in ovaries in JGM-treated females was significantly reduced,down by 32.6%for 1 day after emergence(1DE)and 29.8%(2DE),respectively,compared to the control.In addition,the JH level in JGM-treated females increased by 49.7%and 45.7%at 1DE and 2DE compared to the control,while in relation to the control,the 20E levels reduced by 36.0%and 30.0%at 1DE and 2DE,respectively.The amount of YLS in JGM-treated females increased by 45.9%for 1DE and 34.7%for 2DE,respectively,compared to controls.We therefore concluded that JGM treatments may implicate the lipid metabolism of BPH,which was consistent with our previous evidence that JGM spray treatment and topical treatment stimulate BPH reproduction.