Compatibility Between Beauveria bassiana and Papain and Their Synergistic Potential in the Control of Tenebrio molitor (Coleoptera: Tenebrionidae)

The use of proteolytic enzymes in association with entomopathogenic fungi offers a promising alternative for improving the biological control of insect pests. This study evaluated the compatibility between Beauveria bassiana and papain and the effectiveness of their combined application in controlling Tenebrio molitor. Conidial viability in the presence of papain was monitored for 48 h and showed a reduction in germination from 100% to approximately 70%, without detrimental effects on fungal performance. Papain activity remained stable up to 12 h, declining afterward, indicating biochemical compatibility. Bioassays revealed significant differences among treatments (p < 0.01). In larvae, mortality ranged from 5.18 ± 0.19% in the control to 49.62 ± 2.00% with papain, 62.24 ± 0.58% with conidia, and 89.71 ± 1.06% in the combined treatment; papain and conidia alone did not differ statistically. In pupae, mortality reached 2.20 ± 0.00% in the control, 47.38 ± 0.69% with papain, 63.69 ± 0.69% with conidia, and 85.91 ± 0.84% with the combination, with all treatments differing significantly. Fungal reisolation confirmed typical B. bassiana development. Overall, the results show that papain does not compromise fungal viability and that its combination with B. bassiana enhances entomopathogenic activity, supporting its potential for integrated pest management.