PLANT RESISTANCE Resistance of Potato Germplasm to the Potato Tuberworm (Lepidoptera: Gelechiidae) SILVIA I. RONDON, 1,2,3 DANNY C. HANE, 1,2 CHARLES R. BROWN, 4 M. ISABEL VALES, 2 AND MAHMUT DO ˇ GRAMACI 1,2 J. Econ. Entomol. 102(4): 1649Ð1653 (2009) ABSTRACT The evaluation of potato germplasm for resistance to potato tuberworm, Phthorimaea operculella (Zeller) (Lepidoptera: Gelechiidae), is a valuable component of integrated pest manage- ment; however, few attempts have been made to identify natural genetic tuber resistance to tuber- worm on potato germplasm. The objective of this study was to screen potato germplasm with potential tuberworm resistance for tuber resistance under Þeld and laboratory conditions. Experiments were conducted over a 2-yr period at the Hermiston Agricultural Research and Extension Center, Her- miston, OR. Of 125 germplasm that were tested in 2006, q13 were selected for further screening in 2007. These germplasm were: A0008-1TE, A97066LB, NY123, PA00N10-5, PA99N2, PA99N82, Paciencia, Q174-2, Russet Burbank, Rubi, Ranger Russet, Spunta G2, and T88-4. Tuber resistance of potato germplasm was determined based on the number of mines per tuber and the number of live larvae. Tubers of transgenic clone Spunta G2 were resistant to tuberworm damage. All other germ- plasm tested in this study, including Russet Burbank and Ranger Russet, were susceptible to tuber- worm in the Þeld and laboratory experiments. Incorporation of host plant resistance to tuber pen- etration by larvae together with appropriate cultural practices including limiting exposure time of tubers in the Þeld may provide the best management option in the future. KEY WORDS Columbia Basin, clone, IPM, Phthorimaea operculella, potato The potato tuberworm, Phthorimaea operculella (Zeller) (Lepidoptera: Gelechiidae), is a cosmopoli- tan pest of solanaceous crops including potato, Sola- num tuberosum L. Commonly found in tropical and subtropical regions, potato tuberworm is one of the most important constraints to potato productivity worldwide (Fenemore 1988). Larvae of this species mine leaves, stems, petioles, and excavate tunnels throughout potato tubers. The pest infests plants throughout the growing season; however, the typical damage results from larvae mining the tuber (Rondon et al. 2007). The greatest risk of getting tuber damage caused by the potato tuberworm occurs immediately before harvest, and while the crop is stored in the Þeld awaiting digging, crops that are left in the Þeld for any length of time can become infested (Rondon et al. 2007). The pest is difÞcult to control and over the years growers have relied extensively on the use of insec- ticides (Foot 1974) and a variety of cultural practices (Foot 1974, 1976a; Shelton and Wyman 1979; Clough et al. 2008). Incorporation of host plant resistance to tuber penetration by larvae together with insecticides and appropriate cultural practices such as covering hills and limitation of exposure time in the Þeld may provide the best management option in the future. The evaluation of potato germplasm for resistance to potato tuberworm is valuable to developing inte- grated tuberworm management (Horgan et al. 2007). However, few attempts have been made to identify plant varieties resistant to tuberworm (Foot 1976b, Raman and Palacios 1982, Musmeci et al. 1997). For example, Foot (1976b) compared 20 cultivars for foliar and tuber resistance with negative results. The Inter- national Potato Center tested 3,747 and 452 germ- plasm of primitive and wild potato species, respec- tively, from which 22 primitive and 21 wild germplasm were found resistant (Raman and Palacios 1982). Pre- vious host resistance studies have shown that there are independent resistance mechanisms in the foliage and tubers (Brown 2007). Malakar and Tingey (1999) found limited foliage resistance of Solanum berthaultii Hawkes to potato tuberworm. Musmeci et al. (1997) found some foliar resistance on wild potatoes and interspeciÞc hybrids. Little information is known re- garding the effect of either leaf or tuber resistance on the biology and ecology of potato tuberworm (Malakar and Tingey 1999). The Tri-State Potato Variety Development Program involves a broad-based research effort bringing in ex- pertise from Federal and State sources in Oregon, Wash- ington, and Idaho (http://oregonstate.edu/potatoes/ variety.htm; http://www.ars.usda.gov/research/). The 1 Oregon State University, Hermiston Agricultural Research and Extension Center, Hermiston, OR 97838. 2 Department of Crop and Soil Science, Oregon State University, Corvallis, OR 97331. 3 Corresponding author, e-mail: silvia.rondon@oregonstate.edu. 4 USDAÐARS, Prosser, WA 99350. 0022-0493/09/1649Ð1653$04.00/0  2009 Entomological Society of America Downloaded from https://academic.oup.com/jee/article/102/4/1649/2199291 by guest on 02 March 2022