Leaf herbivory and calcium oxalate crystal production in Prunus avium

Plants require mechanisms of defense to limit the amount of damage by herbivores. Calcium oxalate crystals (COC) in the leaves can serve as inducible defenses against chewing insects, such as Caliroa cerasi larvae. We studied the relationship between leaf COC from Prunus avium and herbivory by C. cerasi larvae, to assess the defensive role of inducible responses. We examined from cafeteria choice experiments the C. cerasi larvae preference towards P. avium cultivars (Bing, Lapins and Van) and larvae preference towards leaves from infested and non-infested trees. The number of damaged leaves per meter of branch and the total non-damaged area and the area removed by the insects was evaluated in the field. We also determined the presence, location, size, and number of crystals in leaves from all studied cultivars. Van and Lapins cultivars were the most preferred by C. cerasi and exhibited a greater number of COC in their leaves, possibly due to being more eaten by the insect. This increase in COC possibly contributes to protect the leaf vein from chewing larvae, maintaining this portion of the vascular transport functionality. Potential manipulations of this induced response could be used in the future as a tool for the pest management against herbivore insects.