Fungi Associated with Horse-Chestnut Leaf Miner Moth Cameraria ohridella Mortality

The total mortality of the leaf-miner horse-chestnut pest, Cameraria ohridella, collected in nature, and the mortality associated with mycoses were assessed under laboratory conditions in stages: for eggs mortality rates of 9.78% and 61.97% were found, respectively; for caterpillars, 45.25% and 5.59%, respectively; and for pupae 21.22% and 100%, respectively. At the egg stage, Cladosporus cladosporioides caused mycosis most often (27% of all mycoses); at the caterpillar stage there was no pronounced predominant fungus species; at the pupal stage both Cordyceps fumosorosea and Beauveria bassiana (32% and 31%, respectively) were most dominant; whereas at the adult stage Lecanicillum aphanocladii (43%) were most dominant. C. ohridella moths remained the most vulnerable during the pupal and caterpillar stages. Maximum diversity of fungi associated with the leaf-miner moth was reached during the period of development inside the chestnut leaf (Shannon–Wiener index—H′ = 2.608 at the caterpillar stage, H′ = 2.619 at the pupal stage), while the minimum was reached in the adult stage (H′ = 1.757). In the caterpillar and pupa stages, saprophytic fungi were most often recorded. Comparative laboratory tests revealed novel properties of the fungus L. aphanocladii, its effectiveness as the leaf-miner moth‘s entomopathogen and its suitability for field application trials while developing environment-friendly methods for horse-chestnut pest control.