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

Irena Nedveckytė,Vincas Būda,Dalė Pečiulytė

doi:10.3390/f12010058

Abstract

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.

Highlights

Horse-chestnut, Aesculus hippocastanum L. (Hippocastanaceae), is widely grown all over Europe in urban greenery, but since the 1980s the decorative value of these trees has fallen sharply due to the spread of the leaf-mining pest Cameraria ohridella Deschka and Dimic (Lepidoptera, Gracillariidae)
Five samplings resulted in a collection of 349 adult moth cadavers, 109 of which had mycosis symptoms (Table 1)
Cladosporium cladosporioides and T. roseum species were the opportunistic fungal pathogens most often recovered. We found the latter fungi to be common on A. hippocastanum foliage; we predict that direct contact could be the reason of the high infection of C. ohridella eggs

Summary

Introduction

Horse-chestnut, Aesculus hippocastanum L. (Hippocastanaceae), is widely grown all over Europe in urban greenery, but since the 1980s the decorative value of these trees has fallen sharply due to the spread of the leaf-mining pest Cameraria ohridella Deschka and Dimic (Lepidoptera, Gracillariidae). (Hippocastanaceae), is widely grown all over Europe in urban greenery, but since the 1980s the decorative value of these trees has fallen sharply due to the spread of the leaf-mining pest Cameraria ohridella Deschka and Dimic (Lepidoptera, Gracillariidae). Cameraria ohridella causes large-scale browning of leaves and pre-mature defoliation of horse-chestnut trees [1,2,3,4,5]. The horse-chestnut leaf miner has been widely studied, including moth biology and distribution [10,11,12,13,14], potential predators [15,16,17,18] and competition either with native leaf miners [19] or phytopathogenic fungi [20]

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