Study On The Feeding Behavior,Development And Reproduction Ability Of White-backed Planthopper On Corn

In recent years,the southern rice black streaked dwarf virus(SRBSDV)by the white-backed planthopper(WBPH),Sogatella furcifera(Horváth)has caused a great economical loss to rice production.Scholars at home and abroad have studied the geographical distribution,transmission vector and transmission route of SRBSDV.The only vector of SRBSDV is S.furcifera(Horváth).North central Vietnam is the direct source area of WBPH migrating north to China and the over-winter area of the migratory population in autumn.However,the investigations found that the period from November to February in the north central Vietnam is the fallow period of rice.WBPH and SRBSDV have no rice host for their survival cycle.At the same time,The investigations revealed a large number of symptoms of SRBSDV on corn in north central Vietnam.So can corn be used as the bridge host of SRBSDV?Can S.furcifera(Horváth)complete the survival cycle by feeding on corn,transferring SRBSDV to corn and retransmitting the virus to rice?If not,can WBPH from other toxic regions migrate to the rice regions in north central Vietnam under the influence of certain weather systems such as typhoons and directly import SRBSDV to complete the survival cycle?In this paper,the feeding behavior of the white-backed planthopper on corn were determined by Electrical penetration graph.The development of the S.furcifera(Horváth)on corn was identified.And whether the corn could complete the survival cycle as the bridge host of SRBSDV was discussed.Based on tracking the course of typhoon and flight path analysis,it is basically clear that the typhoon of the south China sea that made landfall in north central Vietnam after passing through Hainan in July is the vehicle for moving into north central Vietnam with poisonous S.furcifera(Horváth).And the triggering mechanism of SRBSDV outbreak in north central Vietnam is expounded.The main contents are as follows:1.Feeding behavior and nutritional changes of WBPH on cornIn order to explore whether corn can be used as the bridge host of SRBSDV to complete the first step of "storage" of the survival cycle.The feeding behavior of adults of WBPH on different leaf ages corn and the contents of soluble sugar and free amino acid in corn and polypide after feeding were evaluated to determine whether WBPH has the ability to transmit SRBSDV on corn.The results showed that there was no significant difference in feeding behavior of 1-5 day old female adults of WBPH on corn.The total duration of N4-a waves of EPG related to virus transmission exceeded 30 min(more than 5 min in average)on different leaf ages corn.Moreover,the total duration of N4-a on the tasseling corn was significantly higher than other treatment groups.The total duration of N4-b waves related to the virus acquisition was over 80 min(more than 20 min in average).The contents of soluble sugar and free amino acids in the feeding sites of different leaf ages corn were significantly reduced,but the levels in polypide of tested WBPH were significantly increased.So that the hopper obtained nutrition by stabbing.According to the results,it can be known that the adults of WBPH can effectively feed on corn.It had been proved that S.furcifera(Horváth)can transfer SRBSDV from rice to corn and complete the step of"storage" by the perspective of feeding behavior and nutrition acquisition.2.Growth,development and fertility characteristics of WBPH on cornIn order to explore whether corn can be used as the bridge host of SRBSDV to complete the second step of "continuation" of the survival cycle,the fecundity of WBPH on corn and the feeding behavior of 2 instar nymphs on aged corn were measured to determine whether WBPH could reproduce on corn and transmit SRBSDV to rice.The feeding behavior of the second instar nymphs on trumpet corn was analyzed by using EPG to determine whether the nymphs of WBPH can effectively feed on trumpet corn.Observe and compare the fecundity and longevity of WBPH that fed on rice and corn to determine the generational fertility on corn.The results showed that there was no significant difference in the feeding ability between the second instar nymphs and adults.The nymphs can effectively feed on the trumpet corn.There was no significant difference in the proportion of total time in the phloem activity between 2 instar nymphs and adults.The longevity of adults of WBPH on one leaf corn was significantly shorter than that on three leaf corn,and it could not survive normally.The female adults of WBPH that fed on corn had significantly shorter life spans and spawning periods than the rice-feeding group and its oviposition decreased significantly.Nymphs hatching on corn died before the third instar.Both adults and nymphs of WBPH can effectively feed on corn,but they cannot complete the generational reproduction.Corn can not be a host of WBPH,and the bridge host for the southern rice black-streaked dwarf virus.3.The effect of migratory of the white-backed planthopper in Hainan on the survival cycle of virus sources in north central VietnamCorn could not be used as the bridge host of SRBSDV to complete the survival cycle of the virus source of rice region in north central Vietnam.The survival cycle of the virus source in this region may be the direct supplement of the virus source through the migration of vector from other virus source regions under the influence of typhoons and other special weather systems.In order to explore the effect of the migration of WBPH in southern Hainan under the influence of typhoons on the survival cycle of virus source in north central Vietnam,the migration paths and landings of WBPH were studied.In order to spread SRBSDV efficiently in the rice regions of north central Vietnam,WBPH must enter the rice regions in July when the rice are before the jointing period.Then,we studied the amount of light-trap catches in southern Hainan and the typhoons that affected Hainan and landed in Vietnam from July 2013 to 2017.It was found that the light-trap peak occurred only during typhoon no.8 in 2017,which was consistent with the outbreak of SRBSDD in north central Vietnam.Based on the analysis of typhoon "Sonca",various results showed that affected by the typhoon meteorological factors,the migratory population in the virus source region of southern Hainan can crash land in the rice regions of north central Vietnam.This indicates that under the influence of the typhoon,WBPH in the virus region of Hainan can fly directly into north central Vietnam to complete the virus survival cycle and may cause the SRBSDV epidemic.