Evaluation of resistance in different maize varieties to the corn leaf aphid, Rhopalosiphum maidis (Fitch)

The corn leaf aphid, Rhopalosiphum maidis (Fitch), is a major piercing-sucking pest of maize, and its population dynamics are closely related to the level of host plant resistance. To screen for aphid-resistant maize germplasm, this study evaluated the resistance performance of 14 maize varieties and investigated the impact of maize with varying resistance levels on the population development of R. maidis.

Using the aphid density ratio method, the seedling-stage resistance of 14 maize varieties was evaluated under controlled laboratory conditions. Based on preliminary resistance ratings, representative varieties—a highly resistant variety (Longyan 588), a susceptible variety (Qiuqing 1), and a highly susceptible variety (Jinkai 10)—were selected to construct life tables for R. maidis.

The results showed that resistant varieties significantly suppressed aphid population growth. Specifically, first-instar nymphs survived for only about one day on the resistant variety Longyan 588, compared to approximately 2 days on Qiuqing 1 and Jinkai 10. Furthermore, the differentiation rate of alate aphids decreased on resistant plants, whereas the opposite trend was observed on susceptible varieties. The resistance evaluation identified Longyan 588, Keyu 188, Huamu 3, Jinkai 7172, and Jinkai 3 as highly resistant; Nongda 108 as resistant; Yayu 26 as moderately resistant; Hongtai 66, Jinyuanzao 247, and Qiuqing 1 as susceptible; and Qiuqing 88, Yayu 8, Hongtai 826, and Jinkai 10 as highly susceptible. Life table analysis confirmed significant differences in the duration of each life stage and the total generation time among varieties. The highly resistant variety Longyan 588 significantly inhibited nymphal development, resulting in a total generation time of only one day on this variety, which was significantly shorter than the 8.57 days on the susceptible variety Qiuqing 1 and the 7.82 days on the highly susceptible variety Jinkai 10.

Longyan 588 exhibits significant resistance to R. maidis and can therefore serve as a valuable aphid-resistant germplasm resource for subsequent breeding programs and research into resistance mechanisms.