Chemical clues to infection: A pilot study on the differential secondary metabolite production during the life cycle of selected Cordyceps species

Summary

This study examined two types of parasitic fungi (Cordyceps javanica and Cordyceps blackwelliae) that infect insects, comparing how they kill their hosts and what chemical compounds they produce during infection. Researchers found that each species uses different toxic molecules to infect insects, with C. javanica being more deadly and producing diverse compounds called beauveriolides. By analyzing infected insect corpses, scientists provided the first direct evidence that these toxic compounds are actually made during real infections, not just in laboratory cultures.

Background

Cordyceps species are entomopathogenic fungi that produce diverse secondary metabolites with potential roles in host infection and biocontrol applications. The specific roles of these metabolites during the infection process remain unclear, and understanding their chemical strategies could inform biocontrol development.

Objective

To compare the metabolomes and virulence traits of two phylogenetically distinct Cordyceps species (C. javanica and C. blackwelliae) and assess their secondary metabolite production during the infection process against beet armyworms (Spodoptera exigua).

Results

C. javanica showed higher virulence (100% total mortality by day 3) and produced diverse beauveriolides including three previously undescribed derivatives, while C. blackwelliae produced mainly diketopiperazines in vitro but beauvericins in infected cadavers. Bioassays revealed that insecticidal activity is structure-dependent, with beauveriolide I showing notable toxicity while beauveriolide M showed no activity.

Conclusion

The study demonstrates context-dependent metabolic reprogramming in Cordyceps species, with C. javanica and C. blackwelliae employing distinct chemical strategies during infection. The detection of bioactive metabolites in authentic insect cadavers provides direct evidence of their production during natural infection, with implications for understanding host specificity and developing safer biocontrol agents.
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