The availability of water for agriculture is anticipated to become increasingly constrained as a consequence of climate change. Water-stress can promote herbivorous arthropod outbreaks in agricultural systems. Consequently, there has been increased investment in the development of crops capable of tolerating water-stress. However, the efficacy of drought tolerant crops in reducing pest resistance and outbreaks is not well understood. Banks grass and two-spotted spider mites (Acari: Tetranychidae) are major pests on corn, which is an economically important crop in the Intermountain West. The latter is broadly generalist with numerous plant hosts, while the former is a grass specialist. We tested if drought tolerant and drought susceptible corn hybrids in either optimal or water-stressed conditions increased mite populations. A field-cage experiment was conducted using a randomized 2 x 2 x 3 factorial design (two levels each of irrigation and corn drought tolerance for two mite species (present/absent). We found that water-stress resulted in reduced stem diameter, height, and number of cobs, in addition to higher leaf temperature. Our analyses of mite densities are ongoing; however, previous literature suggests that the densities will be greatest on the water-stress and drought susceptible treatments, particularly for the Banks grass mite. The frequency and intensity of water-stress are predicted to become more severe in the western US. We anticipate that drought tolerant traits will become increasingly important for sustaining agriculture production. Further, we recommend that future efforts in pest management integrate plant traits and irrigation practices for more comprehensively understanding pest outbreaks.
