2017 The Netherlands Entomological Society Recent outbreaks in plant diseases associated with Liberibacter pathogens have impacted large areas of western and southern North America. The increase in frequency and severity of drought could render plants more susceptible to the colonization by insect vectors. Experiments were conducted in a laboratory setting to evaluate the influence of water scarcity on drought stress of tomato plants, Solanum lycopersicum L. (Solanaceae). Weekly water treatment of 200, 100, and 50ml resulted in unstressed (control, w=0.55MPa), lowly drought-stressed (LDS, w=0.70 MPa), and moderately drought-stressed (MDS, w=0.87 MPa) plants, respectively. By controlling for both water availability and plant drought stress, the effect of drought stress on S.lycopersicum susceptibility to potato psyllid, Bactericera cockerelli (ulc) (Hemiptera: Triozidae), was evaluated. In a no-choice experiment, MDS plants had significantly more B.cockerelli nymphs than control plants. However, plant susceptibility to B.cockerelli colonization was not due to the oviposition preference for MDS, but rather to the higher B.cockerelli nymphal survival on MDS than on control plants. Nymphal survival of B.cockerelli on MDS plants was consistently and significantly higher than on control plants. Throughout all nymphal stages, B.cockerelli had higher survival on MDS plants than on control plants. Drought stress not only enhanced B.cockerelli survival on S.lycopersicum but it also resulted in 60% more adults produced on water-stressed plants than on control plants. Therefore, as adults can move from plant to plant, drought stress could increase B.cockerelli's dispersion potential. Although plant drought stress improved B.cockerelli survival, it did not affect B.cockerelli oviposition. No difference in number of offspring was found between B.cockerelli adults that developed on MDS vs. control plants. These results might be relevant to B.cockerelli outbreaks and Liberibacter epidemics.
