Summer 2012

CAMPUS RESEARCH UPDATE: Is western flower thrips a single species? by Mark S. Hoddle

Western flower thrips (WFT), Frankliniella occidentalis (fig. 1), is native to the western United States and is a notorious global pest of horticultural and agricultural crops. Much effort has been invested in studying the biology, ecology and management of WFT. Often results from different studies are not consistent and can vary greatly. Recent work by Rugman-Jones et al. at the University of California, Riverside used molecular analyses to investigate the genetic structure of populations of WFT throughout California, and from different countries, or by using appropriate gene sequences for WFT on GenBank. Results revealed that WFT is comprised of two morphologically indistinguishable species that co-occur in California, sometimes being collected simultaneously on the same host plant (e.g., commercially grown plums and peaches). These two species have invaded New Zealand and China, and it is possible that they co-exist in other countries but have not been detected. This study has significant implications for vector transmission studies, biology, behavior and ecology research, and assessing the efficacy of natural enemies and insecticides. A simple molecular technique has been developed to reliably separate these two cryptic species.

References

Rugman-Jones PF, Hoddle MS, Stouthamer R. 2010. Nuclear-mitochondrial barcoding exposes the global pest western flower thrips (Thysanoptera: Thripidae) as two sympatric cryptic species in its native California. Journal of Economic Entomology 103: 877-886.

Fig. 1.  Close-up view of an adult western flower thrips.  Photo by Jack Kelly Clark, UCANR.

Mark S. Hoddle is Cooperative Extension Specialist, Department of Entomology, UC Riverside.