Improved Tospovirus management systems for greenhouse flower crops
Casey C, Sutliff-ShipleyS
Department of Entomology, North Carolina State University, Raleigh, NC 27695, USA.
Correspondence: chris_casey@ncsu.edu
The state of North Carolina has the fourth largest ornamental horticulture industry in the U.S., valued at about $1billion per year. Thrips and tospoviruses cause significant losses for greenhouse flower growers in North Carolina. In greenhouses the predominant virus is impatiens necrotic spot virus (INSV), although mixed infections with TSWV may be present. The western flower thrips, Frankliniella occidentalis, is considered to be the most important vector. A priority for improved greenhouse INSV management is some type of early warning system that would alert growers to the presence of infected thrips before crop symptoms are seen. Indicator plants develop characteristic symptoms within a few days after feeding by viruliferous thrips and serve as an alert to their presence. Since this system will only be effective if the indicator plant is more attractive to the viruliferous thrips than the crops they are intended to protect, we evaluated the relative attractiveness of two indicator plants, petunia and fava bean, and several greenhouse crops, to viruliferous F. occidentalis. Differences between indicator plants species in attractiveness were observed, and in some cases the crop plant was more attractive to thrips than the indicator. Since understanding thrips movement is key to understanding how epidemics develop, we also examined how pesticides might stimulate thrips movement and disease spread. If a pesticide is distasteful (i.e. repellent) a short tasting probe may stimulate vector movement without providing a lethal dose. Common greenhouse pesticides used for thrips and weed control were found to be repellent to F. occidentalis.
