ARTICLE | doi:10.20944/preprints202101.0094.v1
Subject: Biology, Anatomy & Morphology Keywords: Beauveria bassiana; Biological control; Entomopathogenic fungi; Spodoptera frugiperda; Zea mays
Online: 5 January 2021 (13:48:53 CET)
Spodoptera frugiperda is a widely distributed insect pest that causes major economic losses in various crops, particularly maize. On the other hand, Beauveria bassiana is an entomopathogenic fungus that establishes symbiotic associations with many plants and contributes to tolerance against biotic and abiotic stresses. In the present work, under field conditions, 1x106 (first trial) and 1x10⁸ (second trial) of B. bassiana (GHA strain) blastospores were used for corn’s seed inoculation. In the first field trial, a higher number of larvae were present in the negative control plants in comparison with those in B. bassiana-treated plants. No larvae were found in negative control and B. bassiana-treated plants in the second field trial. In further laboratory experiments, the effects of the B. bassiana strains GHA, in addition to a native strain (PTG4) also delivered via seed treatment in maize seedlings, on S. frugiperda growth, development, and mortality were evaluated. 1x10⁶ B. bassiana blastospores were used to inoculate maize seeds, which were germinated and grown to seedlings under growth chamber conditions. Third-instar S. frugiperda larvae were allowed to feed on B. bassiana-treated and -untreated (negative control) seedlings until reaching 6th instar and transferred to artificial diet until reaching adult stage. Results showed that larvae feeding on B. bassiana strain PTG4 prolonged their larval stage. Furthermore, feeding with plants treated with B. bassiana strains yielded fewer S. frugiperda male moths and the female moths emerged with altered wings, compared with the untreated control. In conclusion, seed treatment with B. bassiana in maize reduced S. frugiperda infestation of maize plants in field trials. Besides S. frugiperda development was affected in laboratory trials.
REVIEW | doi:10.20944/preprints202009.0696.v1
Subject: Life Sciences, Biochemistry Keywords: Beauveria bassiana; cuticle degrading enzymes; entomopathogenic fungi; pathogenesis; virulence
Online: 29 September 2020 (08:57:33 CEST)
Intensive crop production and extensive use of harmful synthetic chemical pesticides create numerous socio-economic problems worldwide. Therefore, sustainable solutions are needed for insect pest control, such as biological control agents. The fungal insect pathogen Beauveria bassiana has shown considerable potential as a biological control agent against a broad range of insects. The insights into virulence mechanism of B. bassiana is essential to show the robustness of its use. B. bassiana has several determinants of virulence, including the production of cuticle-degrading enzymes (CDEs), such as proteases, chitinases, and lipases. CDEs are essential in the infection process as they hydrolyze the significant components of the insect's cuticle. Moreover, B. bassiana has evolved effective antioxidant mechanisms that include enzyme families that act as ROS scavengers, e.g., superoxide dismutases, catalases, peroxidases, and thioredoxins. In B. bassiana, the number of CDEs and antioxidant enzymes characterized in recent years. The enzymatic activities are crucial for the biological control potential and significantly advanced our understanding of the infection mechanism of B. bassiana. This review focuses on the progress detailed in the studies of these enzymes and provides an overview of enzymatic activities and their contributions to virulence.