Location: Pest Management and Biocontrol Research
2013 Annual Report
Identifying potential vector species of X. fastidiosa and monitoring vector pressure in Arizona vineyards is a key objective of this project. Yellow-sticky traps were first deployed in April and have been collected biweekly and exchanged for new traps at three vineyard locations in Yavapai County. Light traps were also set up at two locations and have been regularly monitored for leafhoppers and spittlebugs. Trap catches have been limited from all locations so far this year. In addition to being unfamiliar with the potential vector species in Arizona, their seasonal populations patterns are unknown. Specimens collected thus far have been sent to leafhopper specialists for identification so that relative abundances and seasonal timings can be described. It is widely assumed that all xylem feeding insects are potential vectors of X. fastidiosa, a key point that will be used to differentiate leafhopper vectors from leafhopper non-vectors. These two groups can be distinguished based on pronounced mouthpart musculature of xylem-feeding leafhoppers compared with phloem- or parenchyma-feeding leafhoppers. Reports of spittlebug colonization of grapevines are common in Yavapai and Cochise counties where two of the three Arizona wine regions are located. Collections of live spittlebugs on grapevines in Yavapai County were made in October, 2012, and are now in culture in Arid Land Agricultural Research Center (ALARC) greenhouses. Insects from this colony will be used for vector transmission experiments and/or toxicological bioassays with neonicotinoid insecticides.
Reducing the potential of X. fastidiosa spread by eliminating plant inoculum sources and minimizing vector populations and activities in and around vineyards is a central goal of this project and X. fastidiosa management in general. Field trials are underway in three vineyards in Yavapai County to investigate the activity profile of imidacloprid, a neonicotinoid insecticide having antifeedant properties and a record of reducing pathogen transmission by insect vectors. Grapevine leaf samples have been collected biweekly since late April when the first treatment applications were made. A commercially available test kit with a sensitivity limit of 0.2 ppb is being used to quantify imidacloprid titers in leaf samples. These data are being compiled and will be used to develop an activity profile of imidacloprid to characterize its overall persistence and time of peak activity in grapevines. When merged with data on vector phenologies, the goal will be to identify periods of greatest vulnerability in Arizona vineyards to vector pressure so that imidacloprid applications and other control measures can be implemented in the most timely and effective manner.