Comparison of host adaptation in <i>Sitobion miscanthi</i> (Takahashi) (Hemiptera: Aphididae) populations at different time points within the same wheat field

The spatiotemporal variability in resistance to Sitobion miscanthi (Takahashi) among wheat germplasm poses a substantial challenge for wheat breeders attempting to efficiently select and utilize existing germplasm in the development of aphid-resistant wheat varieties. The genetic composition and phenotypic traits of aphid populations within the same wheat field exhibit annual fluctuations, which may explain the unstable field resistance of wheat germplasms to S. miscanthi. In this study, the host adaptability of 4 aphid populations collected from the same wheat field in Yangling, Shaanxi Province, at different time points was evaluated across 5 wheat varieties and 3 barley varieties. The results showed that, following aphid infestation on day 14, the 4 aphid populations exhibited significant differences in their abundance on all host plants except the barley variety Xiyin-2. On day 24, the 4 aphid populations differed significantly in their abundance, total biomass, and mean individual biomass across all host plants. Distinct host-specific differentiation patterns were observed among the 4 populations based on their abundance on days 14 and 24, as well as total and mean individual biomass on day 24. Overall, significant differences in host adaptability were observed among populations sampled from the same field at different times, providing preliminary evidence that temporal variation in aphid population composition may directly contribute to the unstable resistance performance of wheat germplasm under field conditions.