Amongst the insect vectors of plant pathogens, aphids are regarded as the most efficient ones and transmit a major chunk of plant viruses. Their identification, life history, mechanism of virus transmission with an emphasis on the role of transmission determinants in the spread of plant pathogens has been discussed. To explain the transmission mechanism, a typical plant virus from each virus genera has been selected and described. The aphids are known to transmit all four categories of plant viruses viz. non-persistent stylet-borne, non-persistent foregut-borne, persistent-circulative, and persistent-propagative viruses. Based on these relationships, the retention of viruses in their vectors is variable with respect to time and site of location. Viruses under the non-persistent category are retained in the stylet at acrostyle, without circulation in the body and have been depicted through the pictorial presentation. The movement of foregut-borne viruses in the anterior region of the alimentary canal in the body of the vector has been highlighted. To make easily understandable to the reader, the virus path from acquisition by stylets to the alimentary canal, hemolymph, salivary accessory glands and ejection via a salivary duct with salivation into the healthy plant has been shown in persistent plant viruses. The involvement of coat protein and viral encoded proteins in non-persistent and capsid and Read-Through Proteins in persistent category of plant viruses in the transmission has been explained. The role of chaperone produced by bacterial symbionts in the safe movement of the virus has been shown. The role of transmission determinants is made conspicuous in the transmission of plant viruses under all the four categories of relationships. Besides, the spread of bacterial and fungal pathogens through aphids has also been described with examples.