The olive tree (Olea europaea L.) is one of the oldest known cultivated trees worldwide and an iconic species within the Mediterranean Basin. This study evaluated the impact of three bacterial strains, Bacillus subtilis D3, Paenibacillus tundrae M4, and Streptomyces tricolor HM10, on the mortality of the following four mite pests: Oxycenus niloticus, Tegolophus hassani, Aceria olivi, and Tetranychus urticae. B. subtilis D3 confirmed the highest efficacy, causing 91.84–85.36% mortality in laboratory tests and 88.90–84.12% in field trials after five days. In addition, P. tundrae M4 ranked second, achieving 90.49–84.26% mortality in the lab and 87.87–83.81% in the field after one week. S. tricolor HM10 produced 80.06–74.09% mortality in laboratory assays and 76.73–73.36% under the field conditions. Effects on the predatory mites Agistemus exsertus and Amblyseius swirskii were minimal, with mortality ranging from 13.28 to 18.55% in the lab work and 12.46–16.74% in the field experiment. Genome analysis of strain HM10 revealed a biosynthetic gene cluster with predicted terpenes production. Terpenes can cause chemo-osmotic stress and broad membrane-disrupting capabilities. These results highlight the promise of microbial agents for sustainable mite management and provide a foundation for further optimization of bacterial biocontrol strategies.
Al-Azzazy et al. (Fri,) studied this question.