Laboratory and field evaluation of maize resistance to the two-spotted spider mite, Tetranychus urticae

Spider mites are some of the most important agricultural pests worldwide, jeopardizing maize production across many continents. However, mechanisms of resistance to spider mite in maize remain unclear. Here, we report data from resistant and susceptible maize varieties, Jingke968 and Xianyu335 along with their parental lines, and investigate their responses to Tetranychus urticae (Acari: Tetranychidae). A significantly lower female adult mite population and total mite numbers were recorded in the resistant variety, Jingke968, compared to Xianyu335. Similarly, mite fecundity on Jingke968 was substantially lower compared to Xianyu335, which could be associated with its highly resistant parental line Jing92. Stomatal dimensions also showed a close correlation with the fitness of spider mites on the two maize varieties and four parental lines. Tetranychus urticae population numbers under field conditions showed lower mite densities (numbers per plant) in Jingke968 and Jing92 (75% and 89% lower, respectively) than the most sensitive line PH6WC, hinting toward a high level of resistance to spider mites in these maize lines. Our study provides new insights for mechanisms of physical defense to spider mites in maize and contributed to the basis for pest control and breeding of maize varieties.

Automated summary

This study investigates the mechanisms of resistance to spider mites in maize and finds that the resistant variety, Jingke968, has significantly lower mite populations and reproduction compared to the susceptible variety, Xianyu335. Stomatal dimensions are closely correlated with the resistance level. Field observations also demonstrate a higher resistance level to spider mites in Jingke968 and Jing92 compared to the most sensitive line, PH6WC.