Effects Of Tomato Chlorotic Virus On Fecundity Of Biotype Q Bemisia Tabaci

Transmission of plant viruses mostly relies on insect vectors.Plant virus could enhance its transmission by directly modulating the vector or indirectly regulating the host plant to influence the vector.The whitefly,Bemisia tabaci,is a global invasive insect pest with wide distribution and serious damage.Whitefly is one of the main vectors of Tomato chlorosis virus(ToCV),and to reduce the whitefly population can effectively control ToCV.Previously,we showed that feeding on ToCV-infected plants can promote the reproduction of biotype Q whitefly.In this study,using a biotype Q whitefly-ToCV-tomato system,we investigated how ToCV influence whiteflies reproduction,and how to prevent whiteflies fecundity.Fecundity and the relative expression of vitellogenin(Vg)gene of newly emerged whiteflies were measured on ToCV-infected and uninfected tomato plants on days 4,8,12,16,20 and 24.The role of Vg gene on whitefly reproduction was examined in feeding on tomato plants with presence and absence of ToCV by using dietary RNAi.The main results are as follows:1.Whitefly fecundity on ToCV-infected tomato plants was higher than uninfected,and it was increased significantly on 12,16 and 20 days after eclosion.2.Whitefly Vg gene expression was higher when fed on ToCV-infected tomato plants than uninfected,and it was increased significantly on 12,16 days after eclosion.It was basically consistent with the change of fecundity.3.Both the Vg gene expression and number of mature oocytes of female whitefly were significantly decreased after RNAi.However,RNAi had a better effect on Vg gene silencing in whitefly fed on uninfected tomato plants.4.Both on ToCV-infected and uninfected tomato plants,whitefly fed with Vg ds RNAs had significantly lower oviposition in days 7 than control.These results suggested that ToCV-infected tomato plants increases biotype Q whitefly fecundity via elevated Vg gene expression,and whitefly fecundity was reduced after Vg gene was silenced.It revealed the potential molecular mechanism that virus promote its transmission by indirectly affecting host plants to modulate the fecundity of insect vector,and provided important theoretical basis for integrated pest and plant viruses management.