| The green peach aphid,Myzus persicae,is a globally distributed,piercing-sucking pest that cause economically significant losses in a wide range of crops.Prior studies revealed that infection of Myzus persicae densovirus(Mp DV)has a negative impact on the development and fecundity of Myzus persicae with no significant effect on the intrinsic growth rate of the population.Recently,it was found that Mp DV-related sequences integrate in the genome of Myzus persicae.In this study,based on the previously obtained Mp DV-YL genome sequence,we further detected the presence of the virus in M.persicae collected from different regions of our country,and in local populations of hemiptera insects and the aphid parasite wasps,analyzed the integration of Mp DV homologous sequences in the genome of local M.persicae,evaluated the impact of Mp DV on the aphids and effects of low temperature and store time on the infectivity of the virus.The results were listed as following:1.MpDNV is widely present in the populations of M.persicae and its parasite wasps collected from the local greenhouse and fieldPCR amplification using the specific NS primers revealed that Mp DV is widely present in the populations of M.persicae and its parasitoid wasps which collected from the greenhouse and field of Caoxinzhuang Agricultral Station.Also,the virus was detected in a high occurrence rate in the polulations of Aphis citricola and Bemisia tabaci collected from the neighboring greenhouse.In contrast,we did not find the virus in the populations of other aphids or othe hemiptera insects which collected from relatively separative regions in the agricultural station.These results imply that Mp DNV may transmit and spread in the neighbouring populations of aphids and the aphid wasps may play important roles in transmitting the virus.2.MpDNV-related EDEs integrate in multiple sites in the genome of local M.persicae genomeBlast against the reassembed M.persicae G006 genome with Mp DV-YL genome sequence,we found 55 EDEs(Endogenous densovirus-related elements)distribute in different regions of scafford1,scafford2,scafford5,scafford23,and safford125.Using the genome of G006 as the reference sequence,we performed PCR to identify the Mp DNV-related EDEs in local M.persicae genome.Sequencing analysis showed that 48 EDEs distribute in similar scaffords.In comparision with that of G006,recombination and specific sites changes occur in EDEs of the local M.persicae g,suggesting the integration pattern of EDEs may substantially different in distict polulations of M.persicae.3.MpDV infection substantirally impact the reproductive ability and increasement of the population of M.persicaeAnalysis of the specific time life table of healthy aphids and Mp DV-infected aphids revealed that the virus infection substantially reduced the survival rate(lx)and fecundity(mx)of adult M.persicae.Also,the virus infection negatively impacts the intrinsic increasement rate(r),net reproductive rate(R0),and finite rate of increase(λ).In addition,the virus infection dramatically shortened the time of Ovi-days.4.Long time store of MpDV under low temperature conditions reduce the virus infectivityLow temperature and store time combination analysis indicated that short time(1 month)store of infected M.persicae under 4 ℃ may cause the virus partially degradation when compared with that stored under-80 ℃ conditions.However,the ground-infected aphids could efficiently infect the healthy nymphs.In contrast,store the infected aphids for a longer time(3 months)under 4℃ or-80℃ resulted in the ground aphids could not infect healthy nymphs,suggesting that the virus infectivity may be lost after a long time storage.In summay,we found MpDV is widely present in local populationos of M.persicae and its parasite wasps.Mp DV-related EDEs integrate in multiple sites in the genome of local M.persicae.The virus infection substantially affect the fecundity and increasement of the population of M.persicae,and long time incubation of the virus under low temperature negatively impact the infectivity. |
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