Definition

A vector is a living organism (e.g., insect, mite, bird, higher animal, nematode, parasitic plant, human) able to carry and transmit a pathogen and disseminate disease; (in genetic engineering) a vector or cloning vehicle is a self-replicating DNA molecule, such as a plasmid or virus, used to introduce a fragment of foreign DNA into a host cell.

Above: Melon aphids (Aphis gossypii) can transmit some plant-pathogenic viruses.

Etymology. "quantity having magnitude and direction," 1704, from L. vector "one who carries or conveys, carrier," from pp. stem of vehere "carry, convey".

Discussion

Some common vectors of plant pathogens:

Sap-feeding insects: aphids, whiteflies, planthoppers, thrips, psyllids.

Beetles