Paper · 2025 · Ecology and Evolution

Stinging Trichome Density and Morphology of Three Nettle Species Reflect Mountain Gorillas' Feeding Behavior

Alphonse Nyandwi; Winnie Eckardt; Elias Bizuru; et al.

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claims
8
verbatim quotes
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citations
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research areas
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Open access · cc-by

Abstract

ABSTRACT Plants have developed defense mechanisms against herbivory, including stinging trichomes. Unlike smaller trichomes, which deter insects, the larger, biomineralized, stinging trichomes in Urticaceae defend plants from mammals. The trichome tip breaks off, pierces the skin, and injects irritants, causing an immediate sensation of pain. The herbivore will cease consuming the plant. Some herbivores process and consume nettles. Volcanoes National Park (VNP) in Rwanda provides habitat for several large folivores, including the endangered mountain gorilla ( Gorilla beringei beringei ). VNP mountain gorillas feed on stinging nettle species, including Laportea alatipes , Urtica massaica , and Girardinia bullosa . We investigated the link between the importance (proportion) of these stinging nettles in the diet of gorilla groups ranging in the southwest of VNP and their level of defense through assessing trichome density, length, and glandular base length from each plant organ of 15 specimens per nettle species, which were photographed with a scale ruler under a digital microscope. We also videotaped 12 mountain gorillas consuming L. alatipes to examine adapted feeding techniques to cope with stinging trichomes. We found that L. alatipes , which is consumed most frequently of the three study nettles, had a significantly higher stinging trichome density compared to U. massaica and G. bullosa . However, the length of stinging trichomes and glandular bases containing irritating secretions were significantly smaller in L. alatipes and U. massaica than in G. bullosa , from which gorillas almost exclusively avoid consuming aboveground organs covered with long trichomes. This suggests that larger stinging trichomes and secretory glandular bases offer a more effective defense against mountain gorillas than increased trichome density. The trichome density of L. alatipes tended to be higher on top leaves and stem sections, which are consumed by gorillas more frequently compared to lower parts. Plants have evolved in an intricate way to adapt to herbivores' attacks.

Abstract from the paper’s OpenAlex record; open copy licensed cc-by. Read at the source ↗

The text the model read, with the source record’s inline markup (italics, sub- and superscripts) rendered and its character entities decoded; quote offsets refer to the raw text.

Claims 6

Observationobservedoriginal resultsignificant (as stated)measured

Claim · model-written summary

Laportea alatipes, most frequently consumed, had higher trichome density than the two other nettles.

Taxon
L. alatipesLaportea alatipese0
Interactor
gorillasGorillae1herbivore
Outcome
stinging trichome densitye0
Direction
highere0
Comparator
U. massaica and G. bullosae0

Organisms pictured · Representative pictures of the matched species, not figures from the paper.

Gorilla
Gorilla · Interactor · picture of the genus (one of its species)Rennett Stowe from USA · CC BY 2.0 · Wikimedia Commons ↗

Verbatim

e0

“L. alatipes , which is consumed most frequently of the three study nettles, had a significantly higher stinging trichome density compared to U. massaica and G. bullosa .”

✓ located verbatim in the source · abstract, characters 1245–1414 · show in text ↑
e1

“VNP mountain gorillas feed on stinging nettle species”

✓ located verbatim in the source · abstract, characters 595–648 · show in text ↑
Observationobservedoriginal resultsignificant (as stated)measured

Claim · model-written summary

L. alatipes and U. massaica had shorter stinging trichomes than G. bullosa.

Taxon
L. alatipesLaportea alatipese0
Outcome
length of stinging trichomese0
Direction
smallere0
Qualifier
L. alatipes and U. massaicae0
Comparator
G. bullosae0

Verbatim

e0

“the length of stinging trichomes and glandular bases containing irritating secretions were significantly smaller in L. alatipes and U. massaica than in G. bullosa”

✓ located verbatim in the source · abstract, characters 1424–1586 · show in text ↑
Observationobservedoriginal resultsignificant (as stated)measured

Claim · model-written summary

L. alatipes and U. massaica had smaller glandular bases than G. bullosa.

Taxon
L. alatipesLaportea alatipese0
Outcome
glandular basese0
Direction
smallere0
Qualifier
L. alatipes and U. massaicae0
Comparator
G. bullosae0

Verbatim

e0

“the length of stinging trichomes and glandular bases containing irritating secretions were significantly smaller in L. alatipes and U. massaica than in G. bullosa”

✓ located verbatim in the source · abstract, characters 1424–1586 · show in text ↑
Associationobservedoriginal resultmeasured

Claim · model-written summary

Gorillas almost exclusively avoided aboveground organs of G. bullosa with long trichomes.

Taxon
G. bullosaGirardinia bullosae0
Organ / stage
aboveground organse0
Interactor
gorillasGorillae0herbivore
Outcome
avoid consuming aboveground organse0
Direction
avoide0

Organisms pictured · Representative pictures of the matched species, not figures from the paper.

Girardinia bullosa
Girardinia bullosa · TaxonTony KM · CC BY 4.0 · iNaturalist ↗
Gorilla
Gorilla · Interactor · picture of the genus (one of its species)Rennett Stowe from USA · CC BY 2.0 · Wikimedia Commons ↗

Verbatim

e0

“G. bullosa , from which gorillas almost exclusively avoid consuming aboveground organs covered with long trichomes.”

✓ located verbatim in the source · abstract, characters 1576–1691 · show in text ↑
Mechanismauthor interpretationoriginal resultpositivemeasured

Claim · model-written summary

Authors infer that larger trichomes and glandular bases defend nettles more effectively against gorillas than high density.

Taxon
stinging nettle speciesUrtica dioicae1
Organ / stage
stinging trichomes and secretory glandular basese0
Interactor
mountain gorillasGorilla beringeie0herbivore
Outcome
more effective defense against mountain gorillase0

Organisms pictured · Representative pictures of the matched species, not figures from the paper.

Urtica dioica
Urtica dioica · TaxonSkalle-Per Hedenhös · CC BY-SA 4.0 · Wikimedia Commons ↗
Gorilla beringei
Gorilla beringei · InteractorFiver Löcker from Wellington, New Zealand · CC BY-SA 2.0 · Wikimedia Commons ↗

Verbatim

e0

“This suggests that larger stinging trichomes and secretory glandular bases offer a more effective defense against mountain gorillas than increased trichome density.”

✓ located verbatim in the source · abstract, characters 1692–1856 · show in text ↑
e1

“stinging nettle species”

✓ located verbatim in the source · abstract, characters 625–648 · show in text ↑
Associationobservedoriginal resultmeasured

Claim · model-written summary

L. alatipes trichome density tended to be higher on top leaves and stem sections, which gorillas consumed more.

Taxon
L. alatipesLaportea alatipese0
Organ / stage
top leaves and stem sectionse0
Interactor
gorillasGorillae0herbivore
Outcome
trichome densitye0
Direction
highere0
Comparator
lower partse0

Organisms pictured · Representative pictures of the matched species, not figures from the paper.

Gorilla
Gorilla · Interactor · picture of the genus (one of its species)Rennett Stowe from USA · CC BY 2.0 · Wikimedia Commons ↗

Verbatim

e0

“The trichome density of L. alatipes tended to be higher on top leaves and stem sections, which are consumed by gorillas more frequently compared to lower parts.”

✓ located verbatim in the source · abstract, characters 1857–2017 · show in text ↑