Evaluation of the efficacy of Beauveria bassiana and Beauveria brongniartii strains in the biological control of Tetranychus urticae under laboratory conditions.

Abstract

Introduction: The spider mite Tetranychus urticae is an economically significant pest affecting crops such as roses, strawberries, and various vegetables. Chemical control using acaricides has faced limitations due to developing mite resistance and negative environmental impacts. As a more sustainable alternative, the entomopathogenic fungi Beauveria bassiana and Beauveria brongniartii have shown great potential for managing this pest. This study aimed to evaluate their efficacy under laboratory conditions by analyzing pathogenic capability and mite mortality rates when exposed to these fungal strains. Objective: The primary objective was to evaluate the effectiveness of different strains and concentrations of Beauveria bassiana and Beauveria brongniartii in controlling Tetranychus urticae, to determine their viability as biological pest control agents. Methodology: a completely randomized laboratory experiment (3×2 design) was conducted with eight treatments and six replicates. Two fungal strains (Beauveria bassiana and Beauveria brongniartii) were tested at three concentrations (1×10⁸, 1×10⁶, and 1×10⁴ conidia/mL) along with a control group. Mites were exposed to fungal suspensions in Petri dishes, and mortality was monitored over 14 days. Data were analyzed using ANOVA and Tukey's test (p < 0.05) to determine significant differences between treatments. Results: The Beauveria bassiana strain showed higher efficacy in mite control, achieving significant mortality by the eighth day (3.78%). In comparison, Beauveria brongniartii reached only 1.07% mortality during the same period. The highest concentration (1×10⁸ conidia/mL) caused the greatest mortality, though all tested doses proved effective. No significant interaction was observed between strain and concentration (p > 0.05), indicating efficacy depending primarily on the fungal strain used. Conclusions: Beauveria bassiana proved more effective than Beauveria brongniartii in controlling Tetranychus urticae, emerging as a promising sustainable alternative to chemical acaricides. While higher concentrations showed better results, lower doses also demonstrated significant effects. These findings suggest entomopathogenic fungi could be integrated into Integrated Pest Management strategies, with early application optimization providing maximum pest control benefits. General area of study: Agronomy. Specific area of study: Plant Health. Type of article: original.