Susceptibility of Different Aesculus Species to the Horse Chestnut Leaf Miner Moth: Chemical Composition and Morphological Features of Leaves

The susceptibility of seven species of chestnuts to the horse chestnut leaf miner was studied in the arboretum of the Main Botanical Garden of the Russian Academy of Sciences (MBG RAS), taking into account their interspecific characteristics. Using pheromone delta traps, the highest number of Cameraria ohridella moths was shown for Aesculus hippocastanum and the lowest for Aesculus chinensis. A number of anatomical parameters of leaves were investigated, such as the thickness of the epidermal cell wall and the thickness of the palisade and spongy parenchyma layers. As a result, it was shown that the most infected chestnut species had a greater thickness of the nutritious parenchyma tissue. No dependence was found between the degree of susceptibility to the horse chestnut leaf miner and such indicators as the content of chlorophyll a + b and carotenoids in the leaves of seven species of chestnuts. Nevertheless, resistance of different species of the genus Aesculus to Cameraria ohridella under increased tannin content in leaves has been shown. Evaluation of phenolic compounds and flavonoids has not established their reliable role as repellents. The high levels of carbohydrates found during the study contributed to increased susceptibility to the horse chestnut leaf miner.