Biological control of Popillia japonica
Popillia japonica (Coleoptera: Scarabaeidae - EPPO A2 List) originates from Japan and is established in North America and the EPPO region. The larvae feed on roots of a wide range of plants whereas adults feed on foliage of various host plants. In Italy, the efficacy of two biocontrol agents; the fungus Metarhizium anisopliae (Hypocreales: Clavicipitaceae) and the nematode Heterorhabditis bacteriophora (Rhabditida: Heterorhabditidae: EPPO Augmentative BCA PM 6/3) were assessed. These BCAs were applied to the soil using a modified soil seeder which injects liquid into the soil in a precise application. In addition, an insecticide chlorantraniliprole, was also applied. In 2021, trials were carried out in two hay meadows in the Lombardy region of Italy, using water as the control treatment in undisturbed plots as controls. Both biological control agents and the insecticide reduced larval densities at one or the other site, but not at both sites, compared to the control. In spring 2022, drone surveys conducted over the hay meadows did not show differences in grass quality between treatments, including the control plots. M. anisopliae and H. bacteriophora may perform differently depending on the soil conditions and the timing of the application. Further research is required to optimize their use use according to soil properties in specific sites. Using such machinery to apply insecticides directly into the soil has the advantage of minimising drift from spraying.
Sources
Santoiemma G, Battisti A, Ciampitti M, Cavagna B, Bianchi A, Brugnaro S, Glazer I, Gilioli G, Mori N (2024) Soil application of Popillia japonica control agents with a new injector. Phytoparasitica 52, 21 https://doi.org/10.1007/s12600-024-01149-3