Impacts Of Cucurbit Chlorotic Yellows Virus (CCYV) Induced Phytochemical Changes On The Behaviors Of Vector Bemisia Tabaci

Cucumbit chlorotic yellows virus(CCYV)has caused serious damage to crops all over the world,which was exclusively transmitted by Bemisia tabaci in the semipersistent manner.The strong survival ability of B.tabaci enhanced the frequency of viral pathogen epidemics.Previous studies have shown that both persistently and nonpersistently transmitted viruses,via changing host phenotype,influence orientation and performance of vector insect for facilitating virus spread.However,little is known about how the semi-persistently transmitted viruses alter host plant physiological traits and thereby affect vector behaviors.In this study,we would take CCYV,Cucumis sativus and B.tabaci as research objects to explore this issue by using methods of chemical ecology and insect ethology,the results can be concluded as follows:CCYV infection enhanced the attraction of host plant to vector insectsInitially,it was found that vector insects preferred to settle down CCYV-infected Cucumis sativus seedlings in free choice.Then we analyzed the plant volatile by gas chromatography coupled mass spectrometry.Concentrations of total volatiles and terpenes in cucumber plants were notably decreased after CCYV infection,and the concentrations of ?-pinene,?-ocimene,?-farnesene,and nonanal,were responsible for olfactory attraction of B.tabaci,dramatically reduced in CCYV-infected plants.For exploring the key factors that attract vector to CCYV-infected host,we subsequently investigated the visual preference of B.tabaci to CCYV-infected and healthy host.B.tabaci adults presented significant preference to CCYV-infected host.This study indicated that visual cues could play a vital role in vector insects locating virus-infected host plants at short range.Nutrients and defensive chemicals of host plants remarkably reduced after CCYV infectionTotal phenols and tannin in CCYV-infected and healthy plants were test at 5 and 15 days after CCYV infection,which reduced significantly in CCYV-infected group.Soluble sugar and free amino acids were also declined dramatically in CCYV infected plants,which affect vector insects continuous feeding.The reduction of defense substances is conducive for phloem ingestion of vector insects,which directly promotes virus acquirement and inoculation.The decrease of nutrients would benefit to force vector insect move to other plants for virus transmission.In conclusion,CCYV reduced host nutrients like non-persistently transmitted virus,but enhanced the palatability but reduce the fitness of host plants.Flavonoids and lipids may play vital roles in vector insects and host plant interactionsWe analyzed the metabolites profile changes wide-targetly after CCYV infection by using ultrahigh-performance liquid chromatography coupled to mass spectrometry(UHPLC-MS)-based metabolomics.Totally,612 metabolites were detected.Metabolites mainly enriched in flavonoids,lipids,amino acid derivatives biosynthesis etc.At CCYV 7 days inoculation,the content of lipids and flavonoids were remarkably decreased.At CCYV 15 days inoculation,flavonoids were still significantly reduced after CCYV infection.Interestingly,lipids were remarkably enhanced.The reduction of flavonoids may be responsible for promote vector insect to feed on host plant.The significantly different metabolites increased with the infection period.This study implied that lipids may involve in viruses infection process,LPC(lysophosphatidylcholine),LPE(lysophosphatidylethanolamine)were significantly increased at 15 days.The two groups of lipids that mainly involving in virus assembly and movement in plants.Thus,we supposed that CCYV may hij ack the lipids pathways for successful infection and development.According to previous studies,CCYV reduced the palatability of host plants to vector insects.B.tabaci presented poor biological traits on CCYV infected traits.Our study demonstrated that the reduction of nutrients may be correlated with vector development.However,the reduction of phenol and flavonoids are conducive for vector insects feeding on host.This studied identified the vector behavior and host phytochemistry changes caused by CCYV,which support to help understand how a semi-persistently transmitted virus influence vector and host interactions.