Abstract: 【Aim】 The wheat ear stage is a critical period for yield formation and also the key time for the occurrence and control of wheat aphids. Understanding the spatial distribution and interspecies competition of wheat aphids in major wheat-producing regions is essential for formulating regional control strategies and implementing precise pest management. 【Methods】 From April 2021 to June 2023, 17 sample points were selected in the Huang-Huai-Hai wheat region, North China. A five-point sampling method was used to investigate the individual number and vertical distribution of Sitobion avenae, Rhopalosiphum padi, Metopolophium dirhodum, and Schizaphis graminum (coded as sp1, sp2, sp3 and sp4, respectively) on wheat plants. Using niche theory, the niche breadth (B_i), niche overlap (L), and interspecies competition coeffient (α) were calculated to analyze the dominant species, niches, and interspecies competition across different wheat-growing regions. 【Results】 The spatial distribution of the four dominant aphid species in the Huang-Huai-Hai wheat-growing region varied greatly. In Xiangyang (Hubei), Nanjing (Jiangsu), and Xinyang, Zhumadian and Zhoukou (Henan), R. padi was the dominant species, accounting for more than 57.10% of the total aphid population. In Luoyang (Henan) and Linfen (Shanxi), S. avenae was the predominant species, with a proportion of exceeding 81.98%. In Puyang (Henan), Liaocheng and Binzhou (Shandong), Handan, Cangzhou, Baoding and Langfang (Hebei), and Yanqing (Beijing), all the four aphid species were present, with S. avenae being dominant, accounting for 47.17%- 67.63%. Meanwhile, M. dirhodum accounted for approximately 20% of aphids, and S. graminum occurred sporadically, with a proportion of below 2.19%. S. avenae primarily inhabited in the wheat ear and on the flag leaves, where its proportion accounting for over 70% of its distribution. In contrast, R. padi was more evenly distributed across the wheat plants, and relatively concentrated in the ear portion portion, the lower the latitude, the higher the proportion of R. padi in the ear portion. M. dirhodum mainly occurred on the middle-upper leaves of wheat plants, while S. graminum was mostly found on the lower-middle leaves of wheat plants. Among the four aphid species, R. padi had the widest niche, with the average niche breadth of 0.5003, followed by S. avenae, M. dirhodum and S. graminum, with the average niche breadths of 0.2677, 0.2531 and 0.2064, respectively. The niche overlap (L) values between the four aphid species were ranked in a descending order as: L_sp1-2(2.0324)>L_sp3-4(1.9238)>L_sp2-3(1.2898)>L_sp1-3(1.2889)>L_sp2-4(1.2585)>L_sp1-4(0.7606). The interspecies competition coefficient (α) results of the four species of wheat aphids were consistent with the niche overlap results, with the average interspecies competition coefficients ranked in a descending order as: α_sp1-2 (0.7686)>α_sp3-4(0.6948)>α_sp1-3(0.5899)>α_sp2-3(0.4152)>α_sp2-4(0.3841)>α_sp1-4(0.2286). 【Conclusion】 S. avenae and R. padi are the dominant aphid species during the wheat ear stage in the Huang-Huai-Hai wheat-growing region. R. padi dominates in low-latitude areas, where its damage to wheat ear is more severe. In high-latitude areas, M. dirhodum ranks second in dominance after S. avenae, while S. graminum has the lowest proportion. Among the four aphid species, R. padi has the widest niche and exhibits a high niche overlap and competition coefficient with S. avenae. Therefore, it is recommended to focus on controlling S. avenae and R. padi in the southern part of the Huang-Huai-Hai Region, and prioritize the control of S. avenae and M. dirhodum in the northern part.

Key words: Wheat aphids, wheat, dominant species, niche, interspecies competition, Huang-Huai-Hai Region