Survey of Natural Enemies of the Invasive Boxwood Moth Cydalima perspectalis in Southwestern Mediterranean Europe and Biocontrol Potential of a Native Beauveria bassiana (Bals.-Criv.) Vuill. Strain

SIMPLE SUMMARY: Cydalima perspectalis (Lepidoptera: Crambidae), a species native to East Asia that feeds exclusively on Buxus spp., was first detected in Southwestern Germany and the Netherlands in 2007. Today, it is present in many countries in Europe. Since its detection, numerous researchers have studied the biology and the present or potential number of generations of C. perspectalis in European countries. However, less research has been devoted to detecting possible native biotic factors of mortality (predators, parasitoids, entomopathogenic microorganisms or nematodes) capable of reducing the pest populations. In this work, indigenous natural enemies in the boxwood of the southwest Mediterranean region were collected and identified. One of them, a native Beauveria bassiana strain from infected C. perspectalis larvae, showed potential for controlling this invasive crambid. ABSTRACT: Cydalima perspectalis (Lepidoptera: Crambidae), a species native to East Asia, has been especially devastating in the Mediterranean region and Catalonia, northeast Spain, where Buxus sempervirens is an essential component of the natural forest. As an invasive species, the lack of biotic mortality factors in the arrival region has been one of the main factors allowing its expansion. Therefore, this study aimed to collect and identify possible indigenous natural enemies adapting to the new species in the boxwood of the southwest Mediterranean region. Later, the efficacy of some of the collected species for controlling C. perspectalis larvae was tested in laboratory conditions. The larval collection was carried out in successive years in the boxwood of the region. Several collected larvae were infected with an entomopathogen, Beauveria bassiana, or parasitized by Compsilura concinnata, both common in native Lepidoptera caterpillars. The B. bassiana strain was found to be highly virulent against the developed larvae of C. perspectalis, which suggests that B. bassiana may be an effective treatment in parks and gardens when the first overwintering larvae are detected. The biology of the parasitoid identified is not very well known in Europe, which suggests the necessity of studying its biology and alternative hosts in the region in order to improve its population.