Fungus Fighters: How Ants and Their Microbes Protect Plants from Harmful Fungi

Jim Crocker
24th November, 2024

Fungus Fighters: How Ants and Their Microbes Protect Plants from Harmful Fungi

Wood Ants (Formica polyctena)

Photographer: Jean-Paul Boerekamps

Key Findings

  • Researchers at Aarhus University found that wood ants (Formica polyctena) can inhibit plant pathogenic fungi, offering a natural alternative to chemical pesticides
  • Live ants, crushed ant extracts, and washed ant extracts significantly inhibited the growth of apple brown rot (Monilinia fructigena) without affecting other microbes
  • Wood ants transfer microorganisms to surfaces within 10 seconds, and specific bacteria and yeast from these ants can inhibit various plant pathogens like apple scab and gray mold
Plant diseases are a significant economic burden, costing billions of US dollars annually. Traditional approaches have relied heavily on chemical pesticides, but these can have adverse environmental impacts. Recently, research has explored the potential of ants as biocontrol agents against plant pathogens. A study conducted by Aarhus University has provided new insights into how wood ants (Formica polyctena) can inhibit plant pathogenic fungi, potentially offering a natural alternative to chemical pesticides[1]. The study investigated the antimicrobial properties of wood ants and their associated microorganisms through controlled laboratory experiments. The researchers found that live ants, extracts from crushed ants, and extracts from washed ants all significantly inhibited the growth of apple brown rot (Monilinia fructigena). Interestingly, these treatments did not inhibit the growth of other microbes, suggesting a targeted antimicrobial effect. One of the key findings was that wood ants could transfer microorganisms to their surroundings within just 10 seconds of walking across a surface. The researchers isolated the dominant microorganisms deposited by the ants, identifying four bacterial cultures and one yeast. Two of these isolates, strain I3 (related to Pseudomonas sichuanensis and P. entomophila) and strain I1b (related to Bacillus mycoides), demonstrated inhibitory effects against apple brown rot and apple scab (Venturia inaequalis). Additionally, strain I3 inhibited gray mold (Botrytis cinerea) and Fusarium head blight (Fusarium graminearum). These findings suggest that wood ants could serve as effective biological control agents against commercially relevant plant pathogens. The inhibitory effects observed are likely due to antibiotic compounds produced by the microorganisms associated with the ants. This study builds on previous research indicating the potential of ants in agroecosystems. For instance, ants have been shown to reduce the incidence of pear scab and codling moth caterpillars when attracted to pear trees using artificial nectaries[2]. Similarly, wood ants were found to reduce apple scab symptoms when provided with artificial sugar, thereby eliminating ant-attended aphid populations[3]. The use of ants for biocontrol is not entirely new. In oak forests, gall-dwelling ants have been observed to protect their host plants from predators and pathogens, offering an indirect defense mechanism[4]. Moreover, fungus-growing ants use antibiotics from mutualistic bacteria on their exoskeletons and chemical secretions from their glands to combat disease[5]. The current study by Aarhus University expands on these findings by isolating specific microorganisms associated with wood ants that can inhibit a range of plant pathogens. In conclusion, the research highlights the potential of wood ants as a natural solution for managing plant diseases. By leveraging the antimicrobial properties of microorganisms associated with ants, it may be possible to reduce the reliance on chemical pesticides, thereby promoting more sustainable agricultural practices. Further research is needed to explore the practical applications of these findings in real-world agricultural settings, but the results are promising and warrant continued investigation.

Plant ScienceAnimal ScienceMycology

References

Main Study

1) Fungus Fighters: Wood Ants (Formica polyctena) and Their Associated Microbes Inhibit Plant Pathogenic Fungi.

Published 21st November, 2024

https://doi.org/10.1007/s00248-024-02464-2

Related Studies

2) New Tools for Conservation Biological Control: Testing Ant-Attracting Artificial Nectaries to Employ Ants as Plant Defenders.

https://doi.org/10.3390/insects11020129

3) Implementing wood ants in biocontrol: Suppression of apple scab and reduced aphid tending.

https://doi.org/10.1002/ps.7422

4) Gall-Colonizing Ants and Their Role as Plant Defenders: From 'Bad Job' to 'Useful Service'.

https://doi.org/10.3390/insects10110392

5) Reduced biological control and enhanced chemical pest management in the evolution of fungus farming in ants.

https://doi.org/10.1098/rspb.2009.0184


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