Virulence of Beauveria bassiana against Dysmicoccus brevipes on Pineapple (Ananas comosus)

Background: One of the major pests attacking pineapple plants is the mealybug (Dysmicoccus brevipes), an insect belonging to the order Hemiptera and the family Pseudococcidae. This pest infests the roots, basal stems, and lower leaves of the Pineapple plant. One promising alternative is the use of biological control agents, particularly the entomopathogenic fungus B. bassiana. Aims: This study aimed to evaluate the virulence of several isolates of the entomopathogenic fungus Beauveria bassiana in controlling Dysmicoccus brevipes (D. brevipes) on pineapple plants. Methodology: The experiment was arranged in a Completely Randomised Design (CRD) with four treatments and six replications, consisting of isolates BbSP 105, BbSP 217, BbKP 125, and a control (without fungal application). Data were analysed using analysis of variance (ANOVA), followed by an LSD test at a 5% significance level. This research was conducted in the Plant Pest and Disease Laboratory and the Microbiology Laboratory, Department of Agrotechnology, Faculty of Agriculture, Universitas Islam Riau, from January to April 2025. The experiment consisted of four treatments with five replications, using three isolates of the entomopathogenic fungus Beauveria bassiana and one untreated control, resulting in a total of 24 observation units. The experimental procedures included fungal isolate preparation, conidial suspension formulation, preparation of test insects, and application of B. bassiana on Dysdercus brivioides. The observed parameters included nymphal mortality of D. brivioides, daily mortality rate, number of emerged adults, and symptoms of B. bassiana infection on D. brivioides. Results: The results showed that all B. bassiana isolates significantly suppressed the development of D. brevipes. The highest nymphal mortality was recorded in the BbSP 217 treatment, with a mortality rate of 62%, which was significantly higher than in the other treatments, indicating the greater virulence of the BbSP 217 isolate. Moreover, the number of emerging adults was significantly reduced, with only 38% adult emergence in the BbSP 217 treatment compared to 96.66% in the control. These results suggest that all Beauveria bassiana isolates have potential as effective biological control agents, with BbSP 217 being the most effective in suppressing Dysmicoccus brevipes populations on pineapple. Conclusion: The study demonstrated that all tested Beauveria bassiana isolates were effective in suppressing Dysdercus brevipes populations on pineapple plants. Among the isolates, BbSP 217 showed the highest efficacy, resulting in the greatest nymph mortality and the lowest adult emergence compared to the control. These findings highlight the potential of B. bassiana, particularly the BbSP 217 isolate, as a promising biological control agent for managing D. brevipes infestations in pineapple cultivation. The study demonstrated that all tested Beauveria bassiana isolates were effective in suppressing Dysdercus brevipes populations on pineapple plants. These findings highlight the potential of B. bassiana, particularly the BbSP 217 isolate, as a promising biological control agent for managing D. brevipes infestations in pineapple cultivation.