Stephanitis pyrioides Scott, 1874 (Hemiptera: Tingidae) phenology in Oregon

Abstract

The azalea lace bug, Stephanitis pyrioides Scott, 1874, is a serious pest of rhododendrons and azaleas. While it has been present in the Eastern U.S.A. since 1915, it was only detected in the Pacific Northwest in 2008–2009, where it has become a serious emerging pest. Although its biology and control methods have been examined in the eastern states, little information is available about how to manage this pest in western states. A 2.4-year survey was conducted to document its phenology at 3–8 sites in the Willamette Valley of Oregon and check for the presence of natural enemies specializing on lace bugs that are found in the East Coast. Similar to prior studies, eggs were the predominant overwintering stage in Oregon. Three generations of S. pyrioides were observed during monthly inspections of infested plants, while ∼3.5 generations were estimated by degree-day (DD) calculations based upon 11.2°C and 33°C as the lower and upper thresholds, respectively. Egg hatch was observed as early as April at 156 DD based on a 10.2°C lower threshold specific for egg development. These results suggest that early season management in March through May might target overwintered eggs to prevent hatch or target the young nymphs that emerge. Neither of the exotic natural enemies established in the East Coast, the egg parasitoid, Anagrus takeyanus Gordh, 1977, or the predatory mirid, Stethoconus japonicus Schumacher, 1917, were detected when rearing S. pyrioides from eggs or taking shake samples from infested leaves. Future biological control efforts should focus on other natural enemies.