Water and nutrient stress modify aster leafhopper probing behavior in canola plants

Drought-induced stress and nutrient deficiency are the most studied abiotic stresses due to their complex effects on plants. As the consequences of climate change become more apparent, few studies have considered the effects of these abiotic stresses on plant–insect interactions. The aster leafhopper (Hemiptera: Cicadellidae: Macrosteles quadrilineatus Forbes) is the main vector of Aster Yellows phytoplasma (AYp), a plant pathogen that can infect several plant species in the Western Canadian Prairies and the United States Upper Midwest, including cereals and canola. The mechanisms of insect nutrition and AYp transmission have an intimate association with the probing behavior of aster leafhoppers, namely with phloem-associated behaviors such as phloem ingestion and phloem salivation. The aim of this study is to examine the probing behavior of aster leafhoppers on canola grown under water stress, nutrient stress, and controlled conditions using the electropenetrography technique. Aster leafhoppers on stressed plants spent 62–63% of their time probing, while insects on control plants spent 45% of their time doing so. Aster leafhoppers on water-stressed plants were more likely to ingest from xylem tissues compared to insects in the other treatments. While aster leafhoppers from the different treatments spent 14–19% of their time ingesting from phloem, differences were observed in their ability to salivate into these tissues. Insects on nutrient-stressed plants spent more time salivating in the phloem compared to those on control plants, while aster leafhoppers on water-stressed plants rarely displayed this behavior.