Differential colonization of wheat cultivars by two biotypes of Russian wheat aphid (Homoptera: Aphididae)

Abstract

Susceptible and resistance wheat cultivars, Triticum aestivum L, were presented to two biotypes of Russian wheat aphid, Diuraphis noxia (Mordvilko), in multiple choice tests to assay their relative acceptability as host plants. Both apterae (third and fourth instars) and alate adults were offered plants at the two-leaf stage in different cultivar combinations at 22 1 and 16: 8 (L: D) hour photoperiod. Apterae were released from Petri dishes in the center of a circle of test plants, whereas alatae dispersed from a mature aphid colony to settle on plants arranged in rows. Both alatae and apterous nymphs of both biotypes readily colonized all cultivars tested: 2137 , Akron , Ankor , Halt , Jagger , Prairie Red , Stanton , TAM107 , TAM110 , Trego , Yuma , and Yumar . Fewer biotype 1 apterae responded (settled and fed) in the combination containing more resistant (Dn4-and Dny-expressing) cultivars, compared to the combinations that had fewer. The reverse was true for biotype 2 apterae; more aphids responded in the combination containing the largest number of Dn4 expressing cultivars. Differential colonization of cultivars was observed in only one combination, in which biotype 2 apterae colonized Akron and Yumar in larger numbers than they did Stanton and Yuma. A separate experiment confirmed that, 48 hours after infestation, more biotype 2 apterae abandoned plants of Yuma than plants of Yumar. This differential response was likely due to genetic differences between the two near isogenic lines that include the lack of Dn4 expression in Yuma. Choice tests with alatae did not result in differential rates of cultivar colonization by either biotype in any combination tested. These results suggest that young wheat plants appear to lack any meaningful antixenosis toward D. noxia, even though the aphids appear to perceive, and sometimes respond to, certain differences in cultivar suitability.

Virulence of Two Russian Wheat Aphid Biotypes to Eight Wheat Cultivars at Two Temperatures

“…Our results are consistent with the findings of Haley et al (2004), who reported no indication of resistance to biotype 2 in any of the commercial wheat cultivars they tested, but provide greater detail of the disparity between biotypes in life history parameters. However, Qureshi et al (2005) reported differential colonization of biotype 2 apterae in choice tests in which Akron and Yumar were preferred over Stanton and Yuma, and more individuals abandoned plants of Yuma compared with Stanton, Trego, Yumar, and Halt. Our study also included some of the most popular commercial wheat cultivars currently grown in Kansas (Trego, 2137, Jagger, and TAM 110) in addition to popular Colorado cultivars.…”

“…Subsequent observations (Jyoti, 2004, unpublished data) suggested additional disparity between biotypes with respect to their responses to temperature. A previous study (Qureshi et al, 2005) evaluated colonization of commercial wheat cultivars by the two biotypes and reported some differential responses. The present experiments were designed to evaluate the performance of both biotypes of D. noxia on a wider range of commercially available cultivars, particularly those that are most extensively grown in Colorado and Kansas.…”

Polymorphism and Methylation of Four Genes Expressed in Salivary Glands of Russian Wheat Aphid (Homoptera: Aphididae)

“…Populations of D. noxia Biotype 1, collected from wheat Þelds near Hays, KS, and Biotype 2, collected from wheat Þelds near Briggsdale, CO (via the USDA-ARS Plant Science Research Laboratory at Stillwater, OK), were cultured in separate locations in the greenhouse on susceptible ÔJaggerÕ wheat plants at Kansas State University for use in the experiments. The identity of each biotype was veriÞed in diagnostic plant differential greenhouse assays in Stillwater, OK (Biotype 2), and Manhattan, KS (Biotype 1) (Qureshi et al 2005).…”

Polymorphisms in salivary‐gland transcripts of Russian wheat aphid biotypes 1 and 2

“…RWA1 is virulent only to wheat carrying resistance genes Dn1 , Dn8 and Dn9 . RWA2 is virulent to wheat containing any of the Dn genes other than Dn7 (Haley et al ., 2004; Puterka et al ., 2007; Qureshi et al ., 2005). Liu et al .…”