Effects of drought on the induced defence reaction of Scots pine to bark beetle-associated fungi

Abstract

Water stress was imposed on Pinus sylvestris saplings. Predawn leaf water potential was monitored regularly while carbohydrate reserves were quantified in the phloem, xylem and shoots. Trees were inoculated in the bole with a bark beetle Scolytidae, associated fungus at different periods of the year; the induced defence reaction was quantified 2-3 wk later by its length and the total amount of resin. A decrease in the induced reaction (length and resin quantity) was observed in the most severely stressed trees, but no clear relationship could be established between the concentration of carbohydrates and intensity of the defence reaction. -Authors