Transmission of the Pepino mosaic virus by whitefly

Two experiments were conducted to investigate the transmission of the Pepino mosaic virus (PepMV) by the greenhouse whitefly (Trialeurodes vaporariorum) from tomato to tomato. In the 1:1 system (in which a single virus-contaminated plant was placed next to a healthy plant in a cage containing 469 whiteflies on average) the virus was transmitted to three out of 10 plants. In the 1:4 system (in which a virus-contaminated plant was surrounded by four healthy plants in a cage with 601 whiteflies on average) the virus was transmitted to five out of 32 plants. In order to investigate the mechanism involved in the transmission, the insect bodies were washed to determine the external presence of viral particles. The results showed that the number of PepMV particles carried on whitefly bodies was low, with an average occurrence of 1.33 on the 55 whiteflies tested after the insects were in contact with infected plants for 5 days. This low occurrence was confirmed by observation under microscope, which showed an absence of PepMV-contaminated tomato sap on the insect bodies, suggesting that PepMV transmission by whiteflies could occur when they feed on the plant.