Population Growth and Damage Caused by Rhopalosiphum padi (L.) (Hemiptera, Aphididae) on Different Cultivars and Phenological Stages of Wheat

Abstract

Among the aphids associated with wheat and other winter cereals, Rhopalosiphum padi (L.) is currently the predominant species in the wheat growing region of southern Brazil. The damage caused by this aphid occurs by direct feeding and/or by the transmission of pathogenic viruses, such as the Barley/Cereal yellow dwarf virus. In order to estimate the direct damage caused by R. padi on wheat, we evaluated the population growth of this aphid during the tillering and elongation stages and its effects on grain yield components. The experiment was conducted in a screenhouse with three wheat cultivars (BRS Guabiju, BRS Timbaúva, and Embrapa 16). The effect of a period of 16 days, starting from an infestation of 40 aviruliferous aphids/plant, was evaluated and compared to non-infested plants. In both stages, the population growth of R. padi was lower on the BRS Timbaúva. Although infestation caused a reduction in the grain yield of the three cultivars, this effect was lower for BRS Timbaúva. The cultivar Embrapa 16 supported higher infestations and was more tolerant to damage than the BRS Guabiju.

DIMBOA levels in hexaploid Brazilian wheat are not associated with antibiosis against the cereal aphids Rhopalosiphum padi and Sitobion avenae

“…Our data related to the plant resistance (Figs. 4, 5) is in agreement with the data from the literature where the cultivar BRS Timbau´va has shown a lower reduction in grain production after infection with R. padi, while BRS Guabiju is among the ones with highest reduction in productivity (Peruzzo et al 2007;Cezare et al 2011;Savaris et al 2013). Besides that, the resistance of BRS Timbau´va and BRS Guabiju to R. padi detected by others can be correlated to the antibiosis data showed here.…”

“…In this case, an antibiosis-type effect (slower growth of R. padi) could be linked to a tolerance-type effect (low reduction in grain Table 1 where the means and LSD (5%) for statistical comparison are displayed production) in the cultivar BRS Timbau´va. This same result, a lower population growth of R. padi and lower reduction in grain number for BRS Timbau´va when compared to BRS Guabiju, was also observed by Savaris et al (2013). Here, BRS Timbau´va was also one of the genotypes showing best resistance against S. avenae (Fig.…”

“…BRS Guabiju and BRS Timbau´va were chosen due to their difference in resistance to R. padi based on antibiosis and tolerance studies (Peruzzo et al 2007;Savaris et al 2013). BR 32 and PF 869120 are the parents of BRS Timbau´va, and BRS 327, BRS 328, BRS Guamirim and BRS Parrudo are among the modern wheat cultivars released by Embrapa Trigo (year of release from 2005 to 2012).…”

“…For a specific cultivar, one of these characteristics can be more important than the other (Cao et al 2015). Some Brazilian wheat genotypes have been evaluated for tolerance to R. padi and/or BYDV and for antixenosis and antibiosis to S. avenae (Lanzarini et al 2007;Peruzzo et al 2007;Cezare et al 2011;Savaris et al 2013;Silva et al 2013). Although the methodologies employed in these studies were differ-ent from each other, in general, the cultivar BRS Timbau´va is described as resistant (based on antibiosis and tolerance studies) to R. padi and potentially tolerant to BYDV but, on the other hand, it appears to be sensitive (by antibiosis) to S. avenae.…”

Protective effect and economic impact of insecticide application methods on barley

“…Aphids are the major pest of winter cereals and are the most important virus vectors, transmitting about 30% of all plant viruses know to date (Brault et al, 2010). Around 100 aphids per day per plant are estimated to cause about 1% damage to grain yield of wheat cultivars currently in use in Brazil (Savaris et al, 2013). Considering the current aphid population levels in winter cereals in Brazil, the greatest damage is indirect, arising from the transmission of yellow dwarf disease (YDD) (Kennedy & Connery, 2005).…”