Effect of adult Coccinellidae on the spread of a plant virus by an aphid.
The influence of adults of Coccinella californica Mannh. on the spread of a plant virus (bean yellow mosaic virus) transmitted by Acyrthosiphon pisum (Harris) was studied in the field. Aphids in cages containing adult coccinellids frequently moved among food-plants, whereas only 4 of 74 aphids in the coccinellid-free cage left the original plant. New virus infections occurred more often and virus spread further in cages with aphids and coccinellids than in cages with only aphids. The role of predators in the spread of plant viruses by aphids is discussed.