Presence And Distribution Of Chronic Bee Paralysis Virus (CBPV) In Parts Of China And The Effect Of Imidacloprid On The Proliferation Of CBPV

Honeybee is one of the important pollinators for agricultural balance and ecological development.In recent years,the colony losses in several areas have attracting global attention.On the one hand,pesticide residues affect the physiology and behaviors of bees;On the other hand,virus can infect susceptible bees and replicate rapidly.It is likely to lead to a large number of bees'death.Many studies have confirmed that pesticides or pathogens can weaken the bees,but there are still few studies on the interaction between different pathogenic factors that threaten the health of bees,which may be one of the reasons for the large loss of bees.This study investigated the prevalence of eight viruses in 10 provinces,such as CBPV.The whole genome sequence of CBPV Beijing strain was obtained by cloning and sequencing.The obtained data were uploaded to NCBI database and the GeneBank number were KX168412 and KX168413respectively.CBPV negative chains in different tissues were measured by RT-qPCR.The effects of imidacloprid on the copies of CBPV were studied based on the virulence curve of imidacloprid against Apis mellifera ligustica.The experimental results are as follows:1?Seven kinds of viruses can be detected in the Apis mellifera ligustica,except ABPV.Five kinds of viruses can be detected in the Apis cerana cerana,except ABPV?CBPV and VDV-1.The highest proportion of the positive provinces in Apis mellifera ligustica was BQCV and the IAPV,which were 100%and 90%,respectively,followed by 60%of CBPV.The highest proportion of the positive provinces Apis cerana cerana was CSBV which were 80%,followed by 70%of IAPV and BQCV.The highest infection rate in Apis mellifera ligustica was BQCV,which was 64.64%and the highest infection rate in Apis cerana cerana was IAPV,which was 48.89%.CBPV was detected in Henan,Liaoning,Beijing,Gansu,Qinghai and Anhui provinces,and the infection rate was 45.56%in Apis mellifera ligustica,and 0%in Apis cerana cerana.2?At present,there is little information on the whole genome sequence of CBPV in Genebank.Therefore,the whole genome sequence of CBPV RNA1 and CBPV RNA2 obtained in this study,supplementing the CBPV genomic information of China strain.By analyzing the phylogenetic relationship of RdRp and pSP sequence,CBPV-BJ was closely related with the other Chinese and Japanese sequences.3?The copies of CBPV negative chain was measured by RT-qPCR.It was proved that CBPV could replication in different tissues of bees,especially the head and chest.The imidacloprid detection kit was used to determine the presence of imidacloprid in bees.The imidacloprid concentration among17?g/L to 33?g/L in the bee samples,may be the reason of bees'death.4?The virulence regression equation of imidacloprid to Apis mellifera ligustica was y=2.566x+2.839,LC_2.5=0.816 mg/L,LC₅=1.350 mg/L and LC₁₀=2.027 mg/L.The CBPV copies in bees were quantified after feeding crude toxin of CBPV and imidacloprid.The CBPV copies in the CBPV+LC₅ group was significantly higher than that in the crude toxin of CBPV group at 48 h.And the CBPV copies in the three imidacloprid groups was significantly higher than that in the crude toxin of CBPV at 72 h.The CBPV copies in CBPV+LC₁₀group was significantly higher than that in the crude toxin of CBPV group at 96 h.The consequence is that different concentrations of imidacloprid will increase the CBPV expression level.However,the copies of CBPV did not change obviously with the time and imidacloprid concentration.The complexity of the interaction between the two facters can be seen from the experimental data,but this study is only to explore the relationship between these two factors,the future work needs more in-depth research and exploration.