Simple Summary
Over the past ten years, Cameraria ohridella Deschka & Dimic (Lepidoptera: Gracillariidae), a leaf miner of the horse chestnut Aesculus hippocastanum L., has rapidly spread across most of Europe. Although the use of parasitoids offers potential as a biological control method, a number of issues arise that require detailed study of the interactions and contributions of the predators, parasitoids, and pathogens affecting the horse chestnut leaf miner C. ohridella.
Abstract
Cameraria ohridella Deschka & Dimić was recorded from Macedonia in the 1980s (Deschka G, Dimić N (1986)). The primary host plant is Aesculus hippocastanum. In Russia, this pest was first discovered in 2003 in Kaliningrad. Since the first introduction of C. ohridella into Europe, many studies have been conducted on C. ohridella parasitoids to identify natural control factors. In this review, we examine the spread of invasive insects identified in recent years, particularly Ohrid horse chestnut leaf miner (Cameraria ohridella Deschka & Dimić), and consider the strategies used by native parasitoids to defeat this phytophage. The review also discusses entomophages that feed on C. ohridella. Studies show that in Europe, C. ohridella is attacked by a diverse range of parasitoids—predominantly native polyphagous Hymenoptera, with the family Eulophidae predominating. The most significant species are M. frontalis, P. saulius, C. trifasciatus, and P. agraules. Significant regional differences in recorded parasitism levels—ranging from 1% to 33.6%—have been identified; these may be attributed not only to biological and ecological factors (such as host developmental stage preferences, as well as spatial, climatic, and phenological conditions) but also to the calculation methodology. The low effectiveness of the C. ohridella parasitoid complex in Europe is largely due to poor developmental synchrony between the parasitoids and their hosts. The composition of the assemblage in urban plantings is also influenced by habitat type and anthropogenic disturbance, particularly the removal of fallen leaves. Finally, we provide an overview of future research prospects, with an emphasis on the influence of parasitoids on C. ohridella population densities.