The research focuses on understanding climate change on agroecosystems (the ecology of agriculture). This is specifically thorough charting the effects of temperature change upon leafhopper vector behavior, which relates to the spread of Pierce’s disease on grapevines. The headline finding from the research is that global warming exacerbates the disease symptoms seen with infected grapevines.
Pierce’s disease is caused by a bacterium called Xylella fastidiosa. The disease is endemic in northern California, being spread by the blue-green sharpshooter, which only attacks grapevines. Vines become damaged through the bacterium causing a gel to form in the xylem tissue of the vine. This prevents water from being drawn through the vine. In terms of symptoms, the leaves become slightly yellow or red along margins in white and red varieties. This is followed by fruit clusters shriveling or becoming raisin-like.
The new connections have been made based on a mix of biology field work together with a mathematical model. The study has been led by University of California, Riverside entomologist Dr. Matthew Daugherty. The factors considered in the research included the type of disease, the insect vector, and temperature. The research shows how rising temperatures led to variable effects in relation to vectors of diseases (in this case, insects spreading plant diseases).
The data indicates while global warming increases the types of disease symptoms seen with infected grapevines there could also be a limit to the extent that the insects that spread the disease will function under the higher temperatures. This is because the insects do not like feeding on vines that show extensive signs of the disease. In other words, the infections that grape vines contract might become worse but the rate of infection may slowdown.
As Dr. Daugherty explains: “Because the leafhopper vectors of the Pierce’s disease pathogen avoid feeding on diseased vines, pathogen spread declined over time at higher temperatures.” In this sense climate change introduces both a negative effect (a more virulent pathogen) and a positive effect (a reduction in vine infections).
The research is published in the journal Phytobiomes, with the research paper titled “Conflicting Effects of Climate and Vector Behavior on the Spread of a Plant Pathogen.”
