Entomopathogenic Fungi Infecting Lepidopteran Larvae: A Case from Central Argentina

Summary

This research studied how fungi infect and kill moth caterpillars in Argentina, examining how different food plants affect infection rates. The study found that while fungal infections were relatively rare (about 4% of caterpillars), the type of plant the caterpillars ate significantly influenced their chances of getting infected. This has important implications for understanding natural pest control and ecosystem relationships. Impacts on everyday life: • Helps develop better natural pest control methods for agriculture • Improves understanding of how plants naturally defend themselves against insects • Contributes to safer, more sustainable farming practices • Aids in preserving beneficial insects while controlling harmful ones • Advances our knowledge of natural ecosystem relationships

Background

Entomopathogenic fungi are present in most insect populations and have potential for major ecological impact. While abiotic factors affecting pathogen prevalence are well documented, less is known about relevant ecological interactions. The role of food plants as mediators between herbivorous insects and fungal pathogens is increasingly recognized, with plants potentially providing habitat for insect antagonists according to the ‘Bodyguard hypothesis’.

Objective

To study the probability of larvae from three lepidopteran species dying from fungal infection as a function of insect species and food plants in central Argentina. Additionally, to compare species composition of entomopathogens between continents/biomes and provide evidence on entomopathogenicity of fungi from Aspergillaceae and Nectriaceae families.

Results

Fungal infections were found in 3.8% of 978 reared larvae. Eight species-level taxa belonging to three fungal families were detected. Fusarium and Aspergillus were the most abundant genera, comprising 67.5% and 21.6% of infected specimens respectively. Food plant species had a significant effect on fungal prevalence, particularly for the Fusarium fujikuroi species complex. Infection rates were highest (7.1%) on Erigeron bonariensis and Zea mays.

Conclusion

The study revealed low but consistent fungal prevalence similar to observations in other regions. Food plant species significantly influenced infection rates. The fungal communities in Argentina shared genera but not species with European assemblages, suggesting a global pattern in entomopathogenic fungi distribution. Results support reconsidering the role of certain Fusarium and Aspergillus species as insect pathogens rather than merely opportunistic infections.
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