Obliquebanded Leafroller (Lepidoptera: Tortricidae) Resistance to Insecticides in Michigan Apple and Cherry Orchards

“The escalating concern about resistance in C. rosaceana field populations has reinforced the need for continued resistance monitoring and identification of effective tools for integrated pest management programs.” The native North American pest, obliquebanded leafroller, Choristoneura rosaceana (Harris) (Lepidoptera: Tortricidae), is widely distributed and has a broad range of over 50 hosts, but members of the Rosaceae family are preferred (Sanderson and Jackson 1909; Larocque et al. 1999). The p o l y p h a g o u s larva is the injurious stage of C. rosaceana, as it feeds on flower buds, leaves, and developing fruit (Sanderson and Jackson 1909; Reissig 1978). C. rosaceana is a foliage and fruit feeding pest in apple, causing significant damage, especially by the summer generation. In cherry, the foliage and fruit injury caused by C. rosaceana is less serious compared with apple. However, C. rosaceana is a more critical pest in cherry in the late season, when the larvae can be a contaminant in harvested cherries, thus representing a high risk for load rejection due to the U.S. Department of Agriculture zero-tolerance mandate (USDA 1941; Mason and Huber 2002; Wise and Whalon 2009). Historically, C. rosaceana was considered a secondary pest in fruit orchards, but it became a serious pest causing significant damage since outbreak populations began to occur in the late 1970s (Sial and Brunner 2010a, 2012b). Documentation of many cases of insecticide resistance in C. rosaceana populations against conventional insecticides has made this pest problem even more serious (Mushtaq et al. 2002; Smirle et al. 2002, 2003; Sial and Brunner 2012a). Conventional insecticides, especially the organophosphates, were the backbone of control programs at that time, and the resistance phenomenon among C. rosaceana populations against these compounds led to field failures in commercial apple control programs (Bostanian et al. 1985; Waldstein and Reissig 2000; Mushtaq et al. 2002; Sial and Brunner 2012b). Concurrent with the aggravating factor of resistance problems, US Congress passed the Food Quality Protection Act (FQPA) in 1996, which restricted or prevented the use of many conventional insecticides. As a consequence, fruit growers were forced to replace many of the conventional insecticides with This research was funded by Michigan Project GREEEN, Michigan Apple Committee and Michigan Cherry Committee