Biological control of the foxglove aphid using a banker plant with Eupeodes americanus (Diptera: Syrphidae) in experimental and commercial greenhouses

The foxglove aphid, Aulacorthum solani (Kaltenbach) (Hemiptera: Aphididae), has become a significant pest in horticulture as it can build high populations from 10 to 18 degrees C, when no commercially available biocontrol agent is efficient. The American hoverfly, Eupeodes americanus (Wiedemann) (Diptera: Syrphidae), has demonstrated good active flight, oviposition, and larval voracity at low temperature. In the present study, the efficiency of a banker plant system using the American hoverfly was evaluated in a cage experiment (enclosed space) and commercial greenhouses (open environment) at production temperatures (heating temperature was 18 degrees C). The results demonstrate that banker plants with the American hoverfly provided an adequate control of foxglove aphid populations in both environments. In a cage experiment, the predator used the banker plant for nutritional resources and successfully developed and reproduced on them. Green pepper plants infested by foxglove aphids and exposed to hoverflies show a significantly lower abundance of aphids by the end of the trial, compared to the control cages. In commercial greenhouses (real situation), adult hoverflies were able to mate, locate infested plants, and oviposit. Subsequently their offspring provided an efficient control of aphid populations after 6 weeks. This study demonstrates the high potential of a banker plant using hoverflies in greenhouse environments. It also demonstrates the importance of studying new potential biocontrol agents.