Host plant preference and suitability of Systena frontalis (Coleoptera: Chrysomelidae) in container ornamental nursery systems.

Systena frontalis (F.) (Coleoptera: Chrysomelidae) is an economically important pest of container-grown ornamental plants in the eastern United States. Adults cause characteristic shot-hole feeding injury that reduces plant marketability. Although growers report widespread damage across multiple ornamentals, information on adult host plant preference remains inconsistent and largely anecdotal. Thus, the objective of this study was to determine adult feeding preference and host suitability of S. frontalis on 12 major ornamental plant species grown in greenhouses using no-choice and multi-choice assays, and in the field using multi-choice assays. In the greenhouse no-choice assay, feeding damage was greater on panicled hydrangea, azalea, physocarpus, forsythia, weigela, and hibiscus than on the remaining hosts after 5 d. In the greenhouse multi-choice assay, panicled hydrangea and azalea had greater damage than on other hosts after 5 d. In the field multi-choice assay, panicled hydrangea had greater feeding damage than azalea, physocarpus, rose, forsythia, and weigela, followed by crape myrtle, holly, and distylium after 21 d. The emergence of F1 adults was greater from panicled hydrangea than from all other hosts, whereas crape myrtle had the lowest emergence. Panicled hydrangea is the most preferred host, whereas they could feed and cause severe damage on azalea, physocarpus, forsythia, weigela, and hibiscus in the absence of panicled hydrangea, suggesting careful monitoring of these hosts is needed. Although holly and distylium suffered minimal foliar feeding, a high number of F1 adults emerged from these hosts, indicating that low visible injury may not reliably predict belowground host suitability.