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Glandular trichomes appear to function as an indirect defense in Chapmannia floridana

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Mackenzie L. Jenkins
Mackenzie L. Jenkins
Mackenzie L. Jenkins
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Jennifer L. Schafer
Jennifer L. Schafer
Jennifer L. Schafer
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Abstract and Figures

Sticky plant surfaces can entrap small insects, which attracts predatory arthropods that reduce herbivory such that glandular trichomes can function as an indirect defense against herbivores. We investigated whether the glandular trichomes on reproductive shoots of Chapmannia floridana function as an indirect defense against herbivores. We assessed characteristics of C. floridana reproductive shoots in six vegetation types (southern ridge sandhill, rosemary scrub, scrubby flatwoods, degraded scrub, firelane, pasture) within the Florida scrub ecosystem, and we counted the number of living and entrapped arthropods on reproductive shoots and recorded presence of damage to flower buds, flowers, and fruits. The abundance of glandular trichomes was highest at the top of reproductive stems and did not differ among vegetation types. The number of entrapped carrion was positively correlated with the length of the trichome-covered portion of C. floridana reproductive stems, and there was no difference in the number of entrapped carrion among vegetation types. The number of fruits was positively correlated with the number of entrapped carrion. All predatory arthropods found on C. floridana reproductive shoots were spiders. Live herbivore species found on reproductive shoots included grasshoppers, caterpillars, and hemipterans. One-third of shoots had damage to reproductive structures, and the probability of damage to reproductive structures was negatively correlated with the number of entrapped carrion. Our results suggest that glandular trichomes on C. floridana reproductive shoots are acting as an indirect defense, providing an example of this recently recognized function of glandular trichomes in a species that only has trichomes on reproductive shoots.
Carrion entrapped on a C. floridana reproductive stem (a) and a sepal (b). Green lynx spider on a reproductive shoot (c), live caterpillars on a fruit (a one-segmented loment) (d) and flower buds (e), and a live grasshopper on a flower (f). Green lynx spider and a pollinator on a C. floridana reproductive shoot (g)
Carrion entrapped on a C. floridana reproductive stem (a) and a sepal (b). Green lynx spider on a reproductive shoot (c), live caterpillars on a fruit (a one-segmented loment) (d) and flower buds (e), and a live grasshopper on a flower (f). Green lynx spider and a pollinator on a C. floridana reproductive shoot (g)
… 
Boxplot of the number of carrion per centimeter of the trichome-covered portion of C. floridana reproductive stems in southern ridge sandhill (SH), rosemary scrub (RM), scrubby flatwoods (SF), degraded scrub (DS), firelane (FL), and pasture (P) vegetation types. The solid line indicates the median and the dashed line indicates the mean. The boxes show the interquartile range, and the upper and lower whiskers indicate the 90th and 10th percentiles, respectively. Outliers are represented by black points
Boxplot of the number of carrion per centimeter of the trichome-covered portion of C. floridana reproductive stems in southern ridge sandhill (SH), rosemary scrub (RM), scrubby flatwoods (SF), degraded scrub (DS), firelane (FL), and pasture (P) vegetation types. The solid line indicates the median and the dashed line indicates the mean. The boxes show the interquartile range, and the upper and lower whiskers indicate the 90th and 10th percentiles, respectively. Outliers are represented by black points
… 
Relationship between the length of the trichome-covered portion of the stem and the number of carrion entrapped on C. floridana reproductive shoots; all reproductive shoots are included. The solid line shows the fitted model (number of carrion = 1.191 * e0.032*trichome−covered stem length)
Relationship between the length of the trichome-covered portion of the stem and the number of carrion entrapped on C. floridana reproductive shoots; all reproductive shoots are included. The solid line shows the fitted model (number of carrion = 1.191 * e0.032*trichome−covered stem length)
… 
Relationship between the number of carrion entrapped on C. floridana reproductive shoots and the number of fruits on C. floridana reproductive shoots; all reproductive shoots are included. Several reproductive shoots had the same number of carrion and fruits, so points are overlapping. The solid line shows the fitted model (number of fruits = 2.694 * e0.081*number of carrion)
Relationship between the number of carrion entrapped on C. floridana reproductive shoots and the number of fruits on C. floridana reproductive shoots; all reproductive shoots are included. Several reproductive shoots had the same number of carrion and fruits, so points are overlapping. The solid line shows the fitted model (number of fruits = 2.694 * e0.081*number of carrion)
… 
Probability of damage to C. floridana reproductive structures in relation to the number of carrion on the shoot. For probability of damage, 1 = damage (to buds, flowers, and/or fruits) and 0 = no damage. The size of the circles is scaled to the number of shoots with the specific number of trapped carrion. The best-fit logistic regression line is included (b0 = −0.27 (SE = 0.32), b1 = −0.14 (SE = 0.08); R² = 0.036). The odds ratio for carrion is 0.87 (lower 95% CI 0.73, upper 95% CI 1.00)
Probability of damage to C. floridana reproductive structures in relation to the number of carrion on the shoot. For probability of damage, 1 = damage (to buds, flowers, and/or fruits) and 0 = no damage. The size of the circles is scaled to the number of shoots with the specific number of trapped carrion. The best-fit logistic regression line is included (b0 = −0.27 (SE = 0.32), b1 = −0.14 (SE = 0.08); R² = 0.036). The odds ratio for carrion is 0.87 (lower 95% CI 0.73, upper 95% CI 1.00)
… 
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Vol.:(0123456789)
1 3
Arthropod-Plant Interactions (2024) 18:65–75
https://doi.org/10.1007/s11829-023-10011-y
ORIGINAL PAPER
Glandular trichomes appear tofunction asanindirect defense
inChapmannia floridana
MackenzieL.Jenkins1 · JenniferL.Schafer1
Received: 16 February 2023 / Accepted: 12 October 2023 / Published online: 10 November 2023
© The Author(s), under exclusive licence to Springer Nature B.V. 2023
Abstract
Sticky plant surfaces can entrap small insects, which attracts predatory arthropods that reduce herbivory such that glandular
trichomes can function as an indirect defense against herbivores. We investigated whether the glandular trichomes on repro-
ductive shoots of Chapmannia floridana function as an indirect defense against herbivores. We assessed characteristics of C.
floridana reproductive shoots in six vegetation types (southern ridge sandhill, rosemary scrub, scrubby flatwoods, degraded
scrub, firelane, pasture) within the Florida scrub ecosystem, and we counted the number of living and entrapped arthropods
on reproductive shoots and recorded presence of damage to flower buds, flowers, and fruits. The abundance of glandular
trichomes was highest at the top of reproductive stems and did not differ among vegetation types. The number of entrapped
carrion was positively correlated with the length of the trichome-covered portion of C. floridana reproductive stems, and
there was no difference in the number of entrapped carrion among vegetation types. The number of fruits was positively
correlated with the number of entrapped carrion. All predatory arthropods found on C. floridana reproductive shoots were
spiders. Live herbivore species found on reproductive shoots included grasshoppers, caterpillars, and hemipterans. One-third
of shoots had damage to reproductive structures, and the probability of damage to reproductive structures was negatively
correlated with the number of entrapped carrion. Our results suggest that glandular trichomes on C. floridana reproductive
shoots are acting as an indirect defense, providing an example of this recently recognized function of glandular trichomes
in a species that only has trichomes on reproductive shoots.
Keywords Carrion· Florida scrub· Herbivory· Reproduction· Spiders
Introduction
Glandular trichomes on plants can function as an indirect
defense against herbivory by provisioning predatory arthro-
pods with carrion (Romero etal. 2008; Krimmel and Pearse
2013; Karban etal. 2019; Pearse etal. 2020). Small insects
that are entrapped by glandular trichomes, which can include
herbivores entrapped as a direct defense (Levin 1973; Sim-
mons and Gurr 2005), provide a food source to predatory
arthropods that are able to move across sticky plant sur-
faces (Sugiura and Yamazaki 2006; Voigt and Gorb 2010;
Wheeler and Krimmel 2015). The number of entrapped
carrion is positively correlated with glandular trichome den-
sity (Krimmel and Pearse 2013) and stickiness (Karban etal.
2019). Predator abundance is higher on plants with carrion
(Krimmel and Pearse 2013; LoPresti etal. 2015; Nelson
etal. 2020) and is positively correlated with the number
of entrapped carrion (LoPresti and Toll 2017; LoPresti
etal. 2018; Karban etal. 2019). The presence of carrion
and predatory arthropods on plants is associated with lower
abundance of herbivores (Romero etal. 2008; Krimmel and
Pearse 2014; LoPresti etal. 2018) and higher plant reproduc-
tion. Damage to reproductive structures is lower (Romero
etal. 2008; Krimmel and Pearse 2013; LoPresti etal. 2015)
and the number of seed capsules (Karban etal. 2019), seeds
per fruit (LoPresti etal. 2018), and dehisced fruits (Krim-
mel and Pearse 2013) is higher in plants with carrion and/
or predators present.
The location of sticky surfaces on a plant and spatial
variation in the abundance of glandular trichomes may
influence the function of stickiness or its effectiveness
Handling Editor: Dagmar Voigt.
* Jennifer L. Schafer
schaferj@winthrop.edu
1 Department ofBiology, Winthrop University, RockHill, SC,
USA
Content courtesy of Springer Nature, terms of use apply. Rights reserved.
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