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Wood ants produce a potent antimicrobial agent by applying formic acid on tree ‐ collected resin

View Article: PubMed Central - PubMed

ABSTRACT

Wood ants fight pathogens by incorporating tree resin with antimicrobial properties into their nests. They also produce large quantities of formic acid in their venom gland, which they readily spray to defend or disinfect their nest. Mixing chemicals to produce powerful antibiotics is common practice in human medicine, yet evidence for the use of such “defensive cocktails” by animals remains scant. Here, we test the hypothesis that wood ants enhance the antifungal activity of tree resin by treating it with formic acid. In a series of experiments, we document that (i) tree resin had much higher inhibitory activity against the common entomopathogenic fungus Metarhizium brunneum after having been in contact with ants, while no such effect was detected for other nest materials; (ii) wood ants applied significant amounts of endogenous formic and succinic acid on resin and other nest materials; and (iii) the application of synthetic formic acid greatly increased the antifungal activity of resin, but had no such effect when applied to inert glass material. Together, these results demonstrate that wood ants obtain an effective protection against a detrimental microorganism by mixing endogenous and plant‐acquired chemical defenses. In conclusion, the ability to synergistically combine antimicrobial substances of diverse origins is not restricted to humans and may play an important role in insect societies.

No MeSH data available.


Related in: MedlinePlus

Increase in the antifungal activity of resin and glass dipped in 58.5% formic acid, venom‐like, and trophallaxis‐like mixes of synthetic acids, respectively, relative to controls (same materials dipped in water)
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ece32834-fig-0002: Increase in the antifungal activity of resin and glass dipped in 58.5% formic acid, venom‐like, and trophallaxis‐like mixes of synthetic acids, respectively, relative to controls (same materials dipped in water)

Mentions: The treatment with synthetic formic acid at a concentration corresponding to the one of venom increased the inhibitory activity of resin against M. brunneum (Figure 2). Formic acid had a significantly stronger impact on the antifungal activity of resin than of inert glass material, which is indicative of a synergistic interaction (Figure 2; Wilcoxon rank‐sum test: W = 323, p < .0001). The treatment with the venom‐like mix (formic + succinic acids) also increased the antifungal activity of resin, but not more than formic acid alone, at the same concentration (Figure 2). The increase in antifungal activity due to the venom‐like mix was also stronger for resin than for glass (W = 312, p < .0001). The treatment with the trophallaxis‐like mix, which contains more succinic acid and only traces of formic acid, slightly decreased the antifungal activity of resin and had no effect on the antifungal activity of glass (Figure 2; W = 70, p = .0009).


Wood ants produce a potent antimicrobial agent by applying formic acid on tree ‐ collected resin
Increase in the antifungal activity of resin and glass dipped in 58.5% formic acid, venom‐like, and trophallaxis‐like mixes of synthetic acids, respectively, relative to controls (same materials dipped in water)
© Copyright Policy - creativeCommonsBy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC5383563&req=5

ece32834-fig-0002: Increase in the antifungal activity of resin and glass dipped in 58.5% formic acid, venom‐like, and trophallaxis‐like mixes of synthetic acids, respectively, relative to controls (same materials dipped in water)
Mentions: The treatment with synthetic formic acid at a concentration corresponding to the one of venom increased the inhibitory activity of resin against M. brunneum (Figure 2). Formic acid had a significantly stronger impact on the antifungal activity of resin than of inert glass material, which is indicative of a synergistic interaction (Figure 2; Wilcoxon rank‐sum test: W = 323, p < .0001). The treatment with the venom‐like mix (formic + succinic acids) also increased the antifungal activity of resin, but not more than formic acid alone, at the same concentration (Figure 2). The increase in antifungal activity due to the venom‐like mix was also stronger for resin than for glass (W = 312, p < .0001). The treatment with the trophallaxis‐like mix, which contains more succinic acid and only traces of formic acid, slightly decreased the antifungal activity of resin and had no effect on the antifungal activity of glass (Figure 2; W = 70, p = .0009).

View Article: PubMed Central - PubMed

ABSTRACT

Wood ants fight pathogens by incorporating tree resin with antimicrobial properties into their nests. They also produce large quantities of formic acid in their venom gland, which they readily spray to defend or disinfect their nest. Mixing chemicals to produce powerful antibiotics is common practice in human medicine, yet evidence for the use of such &ldquo;defensive cocktails&rdquo; by animals remains scant. Here, we test the hypothesis that wood ants enhance the antifungal activity of tree resin by treating it with formic acid. In a series of experiments, we document that (i) tree resin had much higher inhibitory activity against the common entomopathogenic fungus Metarhizium brunneum after having been in contact with ants, while no such effect was detected for other nest materials; (ii) wood ants applied significant amounts of endogenous formic and succinic acid on resin and other nest materials; and (iii) the application of synthetic formic acid greatly increased the antifungal activity of resin, but had no such effect when applied to inert glass material. Together, these results demonstrate that wood ants obtain an effective protection against a detrimental microorganism by mixing endogenous and plant&#8208;acquired chemical defenses. In conclusion, the ability to synergistically combine antimicrobial substances of diverse origins is not restricted to humans and may play an important role in insect societies.

No MeSH data available.


Related in: MedlinePlus