Can microbial plant biostimulants be useful for soil insect pest control? A review

Abstract: Plant biostimulants are ingredients with the sole aim to improve the agronomic performance of a plant. We listed 483 commercial plant biostimulants based on 245 microorganism species from six countries that have a detailed registration processes and/or an accessible and searchable database for plant biostimulants. Subsequently, we reviewed the found microbial plant biostimulants with regard to their effects on soil insects pests such as for example on rootworms (Diabrotica spp., Coleoptera: Chrysomelidae) via databases of scientific literature. About 66 % of products (154 ± 133) contain microorganisms reported to directly or indirectly affect insect pests, which is 53 % of species (34 ± 8) used in biostimulants. Among them, about 30 % of products (103 ± 86) contain microorganisms reported to affect soil insect pests, which is 44 % of the used species (19 ± 6). At least 20 % of products (41 ± 46) contain microorganisms reported to affect rootworms, which means 9 % of the species (6 ± 2). In conclusion, growers should be made aware of the multiple effects of microbial plant biostimulants.