The English grain aphid, Sitobion avenae, is a major pest species of wheat crops; however, certain varieties may have stronger resistance to infestation than others. Here, we investigated 3 classical resistance mechanisms (antixenosis, antibiosis, and tolerance) by 14 wheat varieties/lines to S. avenae under laboratory and field conditions. Under laboratory conditions, alatae given the choice between 2 wheat varieties, strongly discriminated against certain varieties. Specifically, the ‘Amigo’ variety had the lowest palatability to S. avenae alatae of all varieties. ‘Tm’ (Triticum monococcum), ‘Astron,’ ‘Xanthus,’ ‘Ww2730,’ and ‘Batis’ varieties also had lower palatability than other varieties. Thus, these accessions may use antibiosis as the resistant mechanism. In contrast, under field conditions, there were no significant differences in the number of alatae detected on the 14 wheat varieties. One synthetic line (98-10-30, a cross between of Triticum aestivum (var. Chris) and Triticum turgidum (var. durum) hybridization) had low aphid numbers but high yield loss, indicating that it has high antibiosis, but poor tolerance. In comparison, ‘Amigo,’ ‘Xiaoyan22,’ and some ‘186Tm’ samples had high aphid numbers but low yield loss rates, indicating they have low antibiosis, but good tolerance. Aphid population size and wheat yield loss rates greatly varied in different fields and years for ‘98-10-35,’ ‘Xiaoyan22,’ ‘Tp,’ ‘Tam200,’ ‘PI high,’ and other ‘186Tm’ samples, which were hybrid offspring of T. aestivum and wheat related species. Thus, these germplasm should be considered for use in future studies. Overall, S. avenae is best adapted to ‘Xinong1376,’ because it was the most palatable variety, with the greatest yield loss rates of all 14 wheat varieties. However, individual varieties/lines influenced aphid populations differently in different years. Therefore, we strongly recommend a combination of laboratory and long-term field experiments in targeted planting regions to identify varieties/lines that consistently show high resistance to S. avenae infestation.

The fecundity advantage hypothesis suggests that females with a large body size produce more offspring than smaller females. We tested this hypothesis by exploring the correlations between life-history traits of three aphid species feeding on ten wheat accessions at three levels of analysis with respect to the host plant: overall, inter-accession and intra-accession. We found that fecundity was significantly correlated with mean relative growth rate (MRGR), weight gain and development time and that the faster aphid develops the greater body and fecundity, depending on aphid species, wheat accession and analyses level. Larger aphids of all three species produced more offspring overall; this held true for Sitobion avenae and Schizaphis graminum at the inter-accession level and for S. avenae, Rhopalosiphum padi, and S. graminum for three, five and eight accessions respectively at the intra-accession level. Only one correlation, between intrinsic rates of natural increase (r_m) and MRGR, was significant for all aphid species at all three analysis levels. A more accurate statement of the fecundity advantage hypothesis is that cereal aphids with greater MRGR generally maintain higher r_m on wheat. Our results also provide a method for exploring relationships between individual life-history traits and population dynamics for insects on host plants.

Winter wheat resistance is an efficient and environmentally friendly means to controlling aphids. By using principal component analysis and correlation analysis, we evaluated the resistance of 10 winter wheat varieties or lines from three countries to the following three aphid species: Sitobion avenae, Rhopalosiphum padi, and Schizaphis graminum. The data show that Batis was susceptible to Si. avenae and R. padi, but had adverse effect on the development of Sc. graminum; Astron was advantageous to WG and r_m of Si. avenae and R. padi, but not to Sc. graminum; Amigo was resistant to Sc. graminum and R. padi, but susceptible to Si. avenae; 98-10-35 was resistant to Si. avenae and R. padi, but not to Sc. graminum; 98-10-30 was adverse to growth and fecundity of Si. avenae, but better for Sc. graminum and R. padi; Xiaoyan22 was susceptible to Sc. graminum, but not to R. padi; Ww2730 were resistant to Si. avenae, but susceptible to Sc. graminum; 186tm was susceptible to R. padi, but caused high mortality for Si. avenae and Sc. graminum. Correlation analysis suggests the wheat varieties or lines that were resistant to Si. avenae were always resistant to R. padi, but susceptible to Sc. graminum. However, the overall similarities in resistance classifications were not because of the same phenotypic characters of the wheat varieties or lines. We conclude that the wheat varieties or lines had specific different resistances to the three aphid species, and the resistant traits (antibiosis) can be defined at two or more hierarchical levels. There was even a stronger “trade-off” for the comparison of Si. avenae versus Sc. graminum and R. padi versus Sc. graminum.