Effects Of Two Host Plants On Fecundity And Vitellogenin Gene Expression Of Spodoptera Frugiperda

Spodoptera frugiperda(fall armywarm),Lepidoptera Noctuidae,is a migratory pest originating which is major in tropical and subtropical America.The host plant range of S.frugiperda is very wide.Based on the current study,there is no explicit report on the effects of different host plants for energy substances in adults of S.frugiperda and on the expression of reproductive-related genes,especially Vg gene.This study aims to the investigation of the effects of two host plants on the growth and development,reproductive related indicators,reproductive system development and energy storage in adult stage of S.frugiperda.The effect of feeding two host plants on the relative expression of Vg gene in adults of S.frugiperda was determined by RT-q PCR.The main results are as follows:1.Effects of feeding on two host plants on the growth,development and reproduction of S.frugiperdaAfter the larvae of S.frugiperda fed on maize and E.indica,its growth,development and reproduction-related indicators were significantly different.The larval growth period(day):maize(15.49)> E.indica(19.88).There was no significant difference in pupal stage(day);pupae weight(g): maize(0.203)> E.indica(0.162).In terms of reproduction,the longevity of adults(days),the average fecundity of single female(grains),and the amount of residual eggs(grains)showed significant differences:maize(11.77d;1265.92 grain/one;32.85 grain/one)> E.indica(9.99d;839.82 grain/one;14.95 grain/one);however,there was no significant difference in hatching rate between the two.2.Effects of feeding on two host plants on the reproductive system development of adult of S.frugiperdaThe reproductive system morphology of S.frugiperda,except for Transparent opalescent phase and Terminal phase of oviposition,here was no significant difference in the length of ovarian tube between the two groups(maize:44.63 mm、16.12 mm;E.indica :39.84 mm、13.22 mm).In other periods,the length of ovarian tube in maize was longer than in S.frugiperda.Maize(49.44 mm;59.04 mm;59.17 mm)> E.indica(43.23 mm;48.03mm;46.79 mm).The testis index of males reached the maximum at the early stage of emergence,and then gradually decreased.Except that there was no significant difference between the level IV and the level V,the descending order of maize was maize > E.indica.3.Effects of feeding on two host plants on the content of energy substances in adults of S.frugiperdaWhen the trehalose content was determined,the difference of the content between two groups was not significant except at Yolk deposition phase of the female ovary and the level IV of the male testis,and the difference in the trehalose content was all shown in the order of maize > E.indica in the rest of time.In the determination of soluble protein content,except in the peak phase of oviposition of female ovarian oviposition and in the level IV and V of male testis,there was no significant difference between the two groups.The soluble protein content of maize was higher than E.indica.When the triglyceride content was determined,there was no significant difference between the two groups,except at the Terminal phase of ovipositionof female insects and at the stage of testis IV of male insects,There were significant differences in other periods.Females in the peak phase of oviposition and level V of male : E.indica > maize,other periods all performance : maize > E.indica.4.Molecular structure and expression pattern of Vg gene of S.frugiperdaThe results of RT-qPCR test showed that Vg gene was highly expressed in the reproductive system of female adults and significantly higher than male adults.In this experiment,the relative expression levels of Vg gene in female adults which were fed corn at Transparent opalescent phase,Yolk deposition phase and Egg maturation phase were significantly higher than female adults which were fed E.indica.This research firstly studies the differences in energy substances,development of reproductive system,and relative expression of Vg gene in female ovaries after feeding different host plants.In order to study whether non-crop plants can be intermediate host plants of S.frugiperda and the physiological adaptability of S.frugiperda to different host plants under the insufficient main feeding crops.This thesis provides theoretical basis for the prediction and scientific control of S.frugiperda in the field and lays a foundation for clarifying the molecular mechanism of ovarian development of S.frugiperda.