Effect of honeydew and hosts on plant colonization by the aphid parasitoidEphedrus cerasicola

Females ofEphedrus cerasicola Stary were released into small glasshouses (13.6 m³) or cages (0.125 m³) which contained paprika plants in 2 of the following categories: fresh plants (without honeydew and aphids), honeydew-contaminated plants (aphids removed) and aphid-infested plants (with honeydew). Two hundred females were released into each glasshouse with 20 plants, 10 of each category, while 10 females were released into the cages with 2 plants, one of each category. Control experiments with only fresh plants were conducted in both the glasshouses and the cages. The female parasitoids on each plant were counted at regular intervals for 24 or 48 h in the glasshouse and for 4 h in the cage experiments; this number was used as an indicator of plant preferences. The following preferences were established (preferred plant > less preferred plant): honeydew-plant > fresh plant, aphid-plant > fresh plant, aphid-plant > honeydew-plant. The number of females on the aphid-plants increased throughout the experimental period, whereas the number on the honeydew-plants tended to be more stable.