Background: Cyclotides are a family of plant-derived defense peptides. Results: Parigidin-br1, a novel cyclotide, shows insecticidal activity in vivo and in vitro. Mechanistic insights into the activity were provided by theoretical and electron microscopic studies. Conclusion:The cyclotide disrupts insect cell membranes and has potential applications as a biotechnological insecticide. Significance: The study provides an enhanced understanding of cyclotide activity against a sugarcane insect pest.

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The cyclohexadepsipeptide beauvericin (BEA) is a mycotoxin produced by the fungus Beauveria bassiana (Bals.). Using ELISA, different accessions of B. bassiana, belonging to distinct genetic groups, were analyzed to determine their variability in BEA production. The cytotoxic effect of pure mycotoxins and crude extracts was also tested on insect cell lines SF-9 and SF-21. The results showed that BEA production was significantly different between all strains. Bb 9024 exhibited the highest levels (98.56 mg/l), while Bb 9001 the lowest (15.66 mg/l). Statistical difference was found when BEA CC(50) values (2.81 and 6.94 μM) were compared with those values from others mycotoxins (4.23-11.95 μM). Although no correlation has been observed between beauvericin production and phylogenetic grouping, the results suggest a comprehensible involvement of these metabolites during the infection process. The biological evaluation of metabolites produce by entomopathogenic fungi provides better criteria to design more effective formulations for pest management.