Pathogenicity of Fungi of the Genus Lecanicillium sensu lato against the Predatory Bug Orius laevigatus Fieber (Heteroptera, Anthocoridae) and Effectiveness of Dissemination of Fungal Spores by the Predator against the Peach Aphid Myzus persicae (Sulzer) (Hemiptera, Aphididae)

The compatibility of two biological control agents, the predatory bug Orius laevigatus and entomopathogenic fungi of the genus Lecanicillium sensu lato, was studied. Seven out of 13 investigated Lecanicillium strains of different species revealed low pathogenicity to O. laevigatus females. Mortality of the bugs did not exceed 20% when bean leaves were treated with suspension of conidia at a concentration of 5 × 10⁷ spores/mL before the predator colonization. Three strains: Vl 5 (L. lecanii), Vl 61 (L. muscarium), and Vit 71 (L. attenuatum) showed high pathogenicity against the bugs; by the eighth day, the bug mortality was 47, 58, and 100%, respectively. A reduction in longevity and fecundity of the bug females after their contact with spores of all pathogenic and some non-pathogenic strains was found. Lecanicillium longisporum strain Vl 13 in a concentration of 5 × 10⁷ spores/mL practically did not affect the predatory bugs, and the bug mortality reached 40% when the spore concentration increased to 10⁸ spores/mL. Treatment of eggs of the grain moth Sitotroga cerealella, used as food for O. laevigatus, with spores of strain Vl 13 at a concentration of 5 × 10⁷ spores/mL did not cause a decrease in feeding of female bugs and their longevity, while fecundity of the bugs increased. The transfer of EPF spores to bean leaves by the predatory bugs after their contact with sporulating mycelium was studied and shown to cause the infection of the peach aphid Myzus persicae feeding on these leaves. Mortality of aphids ranged from 51 (for strain Vl 61) to 100% (for strain Vl 13) by the 7th day after the release of aphids on plants. A significant reduction in longevity of the adult bugs transferring spores was found. Only sporadic infestation of O. laevigatus after contact with the spores was observed.