Attract-and-kill stations for management of a temperate fruit fly pest, Rhagoletis indifferens, in cherry

Western cherry fruit, Rhagoletis indifferens, is the key insect pest of cherries in western North America. Processed tart cherries have a zero tolerance for fruit fly larvae, and so strict prevention of fruit infestation must be maintained. Use of a reduced-risk bacterial insecticide, spinosad, formulated with a feeding attractant, GF-120 Naturalyte (Dow AgroSciences, Indianapolis, IN), has proven successful in suppressing R. indifferens populations in Utah tart cherry orchards; however, the bait-insecticide is susceptible to ultraviolet light degradation and is not rainfast, and so must be reapplied every 5-7 days or immediately after a rain event. GF-120 is registered for organic production (OMRI approved). We found that male and female adults were attracted to yellow “killing stations” treated with GF-120. The killing stations reduce the exposure of the bait-insecticide to rain and sunlight. Females preferred yellow over green, and stations treated with GF-120 over 20% sugar solutions, while the trend wasn’t as consistent for males. Females with mature ovaries significantly preferred stations treated with GF-120 with standard concentration of ammonium acetate (1X AA) over those treated with 2X AA, sugar or 0X AA. Studies in 2010 are addressing the effects of GF-120 concentration, field aging, and killing station density on adult attraction and fruit injury. Yellow killing stations show promise as a technology to extend the longevity of GF-120 in the cherry orchard while increasing the numbers of female fruit flies responding to the bait, and could help expand the organic production of cherries in Utah and the West.