Plants

Research

Jump to: Review

12 pages, 1555 KiB

Open AccessArticle

The Hole Truth: Why Do Bumble Bees Rob Flowers More Than Once?

by Judith L. Bronstein, Goggy Davidowitz, Elinor M. Lichtenberg and Rebecca E. Irwin

Plants 2024, 13(17), 2507; https://doi.org/10.3390/plants13172507 - 6 Sep 2024

Viewed by 728

Abstract

Primary nectar-robbers feed through holes they make in flowers, often bypassing the plant’s reproductive organs in the process. In many robbed plants, multiple holes are made in a single flower. Why a flower should be robbed repeatedly is difficult to understand: a hole [...] Read more.

Primary nectar-robbers feed through holes they make in flowers, often bypassing the plant’s reproductive organs in the process. In many robbed plants, multiple holes are made in a single flower. Why a flower should be robbed repeatedly is difficult to understand: a hole signals that a nectar forager has already fed, which would seem likely to predict low rewards. We tested three explanations for this pattern in Corydalis caseana (Fumariaceae), a bumble bee pollinated and robbed plant: (1) multiple holes appear only after all flowers have been robbed once; (2) individual foragers make multiple holes during single visits; and (3) it is more profitable for bees to rob older flowers, even if they have already been robbed. We tested these hypotheses from 2014 to 2016 in a Colorado, USA population using data on robbing rates over time, floral longevity, nectar accumulation in visited and unvisited flowers, and the accumulation of robbing holes across the life of flowers. Multiple holes were already appearing when two-thirds of flowers still lacked a single hole, allowing us to reject the first hypothesis. The second hypothesis cannot offer a full explanation for multiple robbing holes because 35% of additional holes appeared in flowers one or more days after the first hole was made. Repeated sampling of bagged and exposed inflorescences revealed that flowers filled at a constant rate and refilled completely after being drained. Consequently, young flowers are of consistently low value to foragers compared to older flowers even if they had previously been robbed, consistent with the third hypothesis. While further studies are needed, these results offer a simple explanation for the paradoxical clustering of nectar-robbing damage in this and possibly other plant species. Full article

(This article belongs to the Special Issue Plant–Animal Interactions: Exploring Costs and Benefits in Highly Conditional Relationships)

► Show Figures

Figure 1

15 pages, 6062 KiB

Open AccessArticle

The Greasy Pole Syndrome in Alliaria petiolata (Brassicaceae): The Pubescence and Wax Coverage on Stems Reduce Invasion by Lasius niger Ants

by Elena V. Gorb and Stanislav N. Gorb

Plants 2024, 13(14), 1932; https://doi.org/10.3390/plants13141932 - 13 Jul 2024

Viewed by 1225

Abstract

To reduce negative effects of floral visitation by ants, which do not serve as reliable cross-pollinators, some plants have developed a non-floral, stem-based defense mechanism called greasy pole syndrome. In the present study, we examined the effects of two surface features (trichomes and [...] Read more.

To reduce negative effects of floral visitation by ants, which do not serve as reliable cross-pollinators, some plants have developed a non-floral, stem-based defense mechanism called greasy pole syndrome. In the present study, we examined the effects of two surface features (trichomes and three-dimensional epicuticular wax coverage) on stems of Alliaria petiolata plants on visiting frequencies, travelled distances, and running velocities of Lasius niger ants. The experiments were performed with stem samples prepared from different (apical and basal) stem portions showing different surface morphologies (smooth control, covered by wax and trichomes + wax, respectively). The control, mechanically wiped stem samples lacking any surface features were significantly more often visited by ants, where they travelled significantly longer distances and moved with significantly higher velocities, compared to the intact stems. The apical and basal stem portions showed no significant differences in the measured parameters. Based on data obtained, we conclude about the main contribution of the wax to the greasy pole function of the A. petiolata stem via reduction of ant adhesion to the wax-bearing stem surface, whereas trichomes presumably serve as the first barrier for ants approaching usually from the ground level and protect the fragile wax coverage from an excessive deterioration. Full article

(This article belongs to the Special Issue Plant–Animal Interactions: Exploring Costs and Benefits in Highly Conditional Relationships)

► Show Figures

Figure 1

13 pages, 1869 KiB

Open AccessArticle

Contrasting Phenological Patterns and Reproductive Strategies in Closely Related Monoecious Fig Tree Species

by Monise T. Cerezini, Ludmila Rattis, Paulo R. Furini and Rodrigo A. S. Pereira

Plants 2024, 13(14), 1889; https://doi.org/10.3390/plants13141889 - 9 Jul 2024

Viewed by 1318

Abstract

Understanding the ecological and evolutionary aspects of mutualistic interactions is essential for predicting species responses to environmental changes. This study aimed to investigate the phenological patterns and reproductive strategies in two closely related fig tree species, Ficus citrifolia and Ficus eximia. We [...] Read more.

Understanding the ecological and evolutionary aspects of mutualistic interactions is essential for predicting species responses to environmental changes. This study aimed to investigate the phenological patterns and reproductive strategies in two closely related fig tree species, Ficus citrifolia and Ficus eximia. We monitored 99 F. citrifolia and 21 F. eximia trees weekly from January 2006 to April 2011 in an area close to the southern edge of the tropical region in Brazil. Our results revealed contrasting phenological patterns between the two species, with F. citrifolia displaying an annual flowering pattern (1.4 episodes per tree per year) and F. eximia a supra-annual pattern (0.5 episodes per tree per year). We also found significant differences in reproductive strategies, with F. eximia producing more pistillate flowers and, consequently, more seeds and pollinating wasps per fig than F. citrifolia, likely as an adaptation to overcome limitations of low population density by maximizing the gene flow. As the shorter-lived organism, the fig wasp was found to influence critical processes associated with the success and stability of mutualism, such as fig development and ripening. Our findings emphasize the importance of understanding the intricate interactions between mutualistic partners and their adaptive responses to environmental conditions in shaping fig tree populations’ reproductive strategies and genetic structure. Full article

(This article belongs to the Special Issue Plant–Animal Interactions: Exploring Costs and Benefits in Highly Conditional Relationships)

► Show Figures

Figure 1

21 pages, 11798 KiB

Open AccessArticle

Tolerance Mitigates Gall Effects When Susceptible Plants Fail to Elicit Induced Defense

by Janete Ferreira Andrade, Eduardo Soares Calixto, Guilherme Ramos Demetrio, Henrique Venâncio, Marcos Vinicius Meiado, Denise Garcia de Santana, Pablo Cuevas-Reyes, Wanessa Rejane de Almeida and Jean Carlos Santos

Plants 2024, 13(11), 1472; https://doi.org/10.3390/plants13111472 - 26 May 2024

Viewed by 1233

Abstract

Variations in plant genotypes and phenotypes are expressed in ways that lead to the development of defensive abilities against herbivory. Induced defenses are mechanisms that affect herbivore insect preferences and performance. We evaluated the performance of resistant and susceptible phenotypes of Bauhinia brevipes [...] Read more.

Variations in plant genotypes and phenotypes are expressed in ways that lead to the development of defensive abilities against herbivory. Induced defenses are mechanisms that affect herbivore insect preferences and performance. We evaluated the performance of resistant and susceptible phenotypes of Bauhinia brevipes (Fabaceae) against attacks by the gall-inducing insect Schizomyia macrocapillata (Diptera). We hypothesized that there is a positive relationship between resistance to S. macrocapillata and host plant performance because resistance can have a high adaptive value. We evaluated plant architecture, nutritional leaf quality, leaf fluctuating asymmetry, and reproductive capacity between phenotypes. Plant performance was evaluated at three ontogenetic stages: seed, seedling, and juvenile. Overall, there were no differences in vegetative and reproductive performance or asymmetry between the resistant and susceptible mature plants. We found no relationship between leaf nutritional quality and resistance to S. macrocapillata. Plant performance was consistent across ontogeny for both phenotypes, except for five variables. Contrary to our expectations, the susceptible plants performed equally well or better than the resistant plants, suggesting that tolerance and overcompensation to herbivory in B. brevipes may be mediated by induced defense. Our study highlights the importance of multiple layers of plant defense against herbivory, where plant tolerance acts as a secondary barrier in plants susceptible to gall-inducing insects. Full article

(This article belongs to the Special Issue Plant–Animal Interactions: Exploring Costs and Benefits in Highly Conditional Relationships)

► Show Figures

Figure 1

12 pages, 5300 KiB

Open AccessArticle

Effects of Florivory on Floral Visitors and Reproductive Success of Sagittaria lancifolia (Alismataceae) in a Mexican Wetland

by Dulce Rodríguez-Morales, Armando Aguirre-Jaimes and José G. García-Franco

Plants 2024, 13(4), 547; https://doi.org/10.3390/plants13040547 - 17 Feb 2024

Viewed by 1104

Abstract

Florivores consume floral structures with negative effects on plant fitness and pollinator attraction. Several studies have evaluated these consequences in hermaphroditic plants, but little is known about the effects on monoecious and dioecious species. We characterize the florivory and its effects on floral [...] Read more.

Florivores consume floral structures with negative effects on plant fitness and pollinator attraction. Several studies have evaluated these consequences in hermaphroditic plants, but little is known about the effects on monoecious and dioecious species. We characterize the florivory and its effects on floral visitors and reproductive success in a monoecious population of Sagittaria lancifolia. Five categories of florivory were established according to the petal area consumed. Visits were recorded in male and female flowers within the different damage categories. Reproductive success was evaluated through fruit number and weight, as well as the number of seeds per fruit. Our results show that the weevil Tanysphyrus lemnae is the main florivore, and it mainly damages the female flowers. Hymenoptera were recorded as the most frequent visitors of both male and female flowers. Male and female flowers showed differences in visit frequency, which decreases as flower damage increases. Reproductive success was negatively related to the level of damage. We found that florivory is common in the population of S. lancifolia, which can exert a strong selective pressure by making the flowers less attractive and reducing the number of seeds per fruit. Future studies are needed to know how florivores affect plant male fitness. Full article

(This article belongs to the Special Issue Plant–Animal Interactions: Exploring Costs and Benefits in Highly Conditional Relationships)

► Show Figures

Figure 1

10 pages, 1792 KiB

Open AccessArticle

Plant Reproductive Success Mediated by Nectar Offered to Pollinators and Defensive Ants in Terrestrial Bromeliaceae

by Carolina Torres, Mariana P. Mazzei, José L. Vesprini and Leonardo Galetto

Plants 2024, 13(4), 493; https://doi.org/10.3390/plants13040493 - 8 Feb 2024

Viewed by 1401

Abstract

Most plants produce floral nectar to attract pollinators that impact pollination and seed production; some of them also secrete extrafloral nectar harvested by insects that may influence the plant reproductive success. The aim of this study was to analyze the effects of excluding [...] Read more.

Most plants produce floral nectar to attract pollinators that impact pollination and seed production; some of them also secrete extrafloral nectar harvested by insects that may influence the plant reproductive success. The aim of this study was to analyze the effects of excluding pollinators and/or ants on the per-plant reproductive success in two species (Dyckia floribunda Griseb. and Dyckia longipetala Baker, Bromeliaceae) that produce floral and extrafloral nectar. The hypothesis states that both ecological processes (pollination and ant defense) involving nectar-mediated animal–plant interactions are beneficial for plant reproductive success. We expected the highest decrease in the plant fruit and seed sets when the pollinators and ants were excluded, and a moderate decrease when solely ants were excluded, compared to the control plants (those exposed to pollinators and ants). In addition, a lower natural reproductive success was also expected in the self-incompatible D. longipetala than in the self-compatible D. floribunda, as the former totally depends on animal pollination for seed production. D. floribunda and D. longipetala presented similar trends in the response variables, and the expected results for the experimental treatments were observed, with some variations between species and among populations. The ecological function of nectar is important because these two plant species depend on pollinators to produce seeds and on ants to defend flowers from the endophytic larvae of Lepidoptera. The study of multispecies interactions through mechanistic experiments could be necessary to clarify the specific effects of different animals on plant reproductive success. Full article

(This article belongs to the Special Issue Plant–Animal Interactions: Exploring Costs and Benefits in Highly Conditional Relationships)

► Show Figures

Graphical abstract

12 pages, 1472 KiB

Open AccessFeature PaperArticle

Spider–Plant Interaction: The Role of Extrafloral Nectaries in Spider Attraction and Their Influence on Plant Herbivory and Reproduction

by Karoline Pádua de Oliveira Dias and Vanessa Stefani

Plants 2024, 13(3), 368; https://doi.org/10.3390/plants13030368 - 26 Jan 2024

Viewed by 1250

Abstract

Spiders, abundant and diverse arthropods which occur in vegetation, have received little attention in studies investigating spider–plant interactions, especially in plants which have extrafloral nectaries (EFNs). This study examines whether spiders attracted to EFNs on the plant Heteropterys pteropetala (Malpighiaceae) function as biological [...] Read more.

Spiders, abundant and diverse arthropods which occur in vegetation, have received little attention in studies investigating spider–plant interactions, especially in plants which have extrafloral nectaries (EFNs). This study examines whether spiders attracted to EFNs on the plant Heteropterys pteropetala (Malpighiaceae) function as biological protectors, mitigating leaf herbivory and positively impacting plant fitness, through manipulative experiments. Spiders are attracted to EFNs because, in addition to consuming the resource offered by these structures, they also consume the herbivores that are attracted by the nectar. At the same time, we documented the reproductive phenology of the plant studied and the abundance of spiders over time. Our results revealed that the plant’s reproductive period begins in December with the emergence of flower buds and ends in April with the production of samarids, fruits which are morphologically adapted for wind dispersal, aligning with the peak abundance of spiders. Furthermore, our results demonstrated that spiders are attracted to plants that exude EFNs, resulting in a positive impact on reducing leaf area loss but with a neutral effect on protecting reproductive structures. By revealing the protective function of spiders’ vegetative structures on plants, this research highlights the ecological importance of elucidating the dynamics between spiders and plants, contributing to a deeper understanding of ecosystems. Full article

(This article belongs to the Special Issue Plant–Animal Interactions: Exploring Costs and Benefits in Highly Conditional Relationships)

► Show Figures

Figure 1

12 pages, 1419 KiB

Open AccessArticle

Chemical Camouflage Induced by Diet in a Pest Treehopper on Host Plants

by Luan Dias Lima, Amalia Victoria Ceballos-González, Amanda Prato, Adriano Cavalleri, José Roberto Trigo and Fábio Santos do Nascimento

Plants 2024, 13(2), 216; https://doi.org/10.3390/plants13020216 - 12 Jan 2024

Cited by 3 | Viewed by 1309

Abstract

Ants patrol foliage and exert a strong selective pressure on herbivorous insects, being their primary predators. As ants are chemically oriented, some organisms that interact with them (myrmecophiles) use chemical strategies mediated by their cuticular hydrocarbons (CHCs) to deal with ants. Thus, a [...] Read more.

Ants patrol foliage and exert a strong selective pressure on herbivorous insects, being their primary predators. As ants are chemically oriented, some organisms that interact with them (myrmecophiles) use chemical strategies mediated by their cuticular hydrocarbons (CHCs) to deal with ants. Thus, a better understanding of the ecology and evolution of the mutualistic interactions between myrmecophiles and ants depends on the accurate recognition of these chemical strategies. Few studies have examined whether treehoppers may use an additional strategy called chemical camouflage to reduce ant aggression, and none considered highly polyphagous pest insects. We analyzed whether the chemical similarity of the CHC profiles of three host plants from three plant families (Fabaceae, Malvaceae, and Moraceae) and the facultative myrmecophilous honeydew-producing treehopper Aetalion reticulatum (Hemiptera: Aetalionidae), a pest of citrus plants, may play a role as a proximate mechanism serving as a protection against ant attacks on plants. We found a high similarity (>80%) between the CHCs of the treehoppers and two of their host plants. The treehoppers acquire CHCs through their diet, and the chemical similarity varies according to host plant. Chemical camouflage on host plants plays a role in the interaction of treehoppers with their ant mutualistic partners. Full article

(This article belongs to the Special Issue Plant–Animal Interactions: Exploring Costs and Benefits in Highly Conditional Relationships)

► Show Figures

Graphical abstract

13 pages, 3698 KiB

Open AccessEditor’s ChoiceArticle

Context-Dependent Ant-Pollinator Mutualism Impacts Fruit Set in a Hummingbird-Pollinated Plant

by Priscila Bruno Cardoso, Eduardo Soares Calixto, Helena Maura Torezan-Silingardi and Kleber Del-Claro

Plants 2023, 12(21), 3688; https://doi.org/10.3390/plants12213688 - 26 Oct 2023

Viewed by 3961

Abstract

Context-dependence in mutualisms is a fundamental aspect of ecological interactions. Within plant-ant mutualisms, particularly in terms of biotic protection and pollination, research has predominantly focused on elucidating the benefits while largely overlooking potential costs. This notable gap underscores the need for investigations into [...] Read more.

Context-dependence in mutualisms is a fundamental aspect of ecological interactions. Within plant-ant mutualisms, particularly in terms of biotic protection and pollination, research has predominantly focused on elucidating the benefits while largely overlooking potential costs. This notable gap underscores the need for investigations into the drawbacks and trade-offs associated with such mutualistic relationships. Here, we evaluated the role of pericarpial nectaries (PNs) in shaping the dynamics of ant-pollinator mutualisms. Specifically, we investigated whether ants visiting the PN of Palicourea rigida (Rubiaceae) could deter hummingbirds and disrupt pollination, ultimately influencing fruit production. Our research involved manipulative experiments and observation of ant-pollinator interactions on P. rigida plants in the Brazilian savannah. We found that visiting ants can deter hummingbirds and/or disrupt pollination in P. rigida, directly influencing fruit set. However, these results are species-specific. The presence of very aggressive, large predatory ants, such as E. tuberculatum, had a negative impact on hummingbird behavior, whereas aggressive mid-sized ants, such as C. crassus, showed no effects. Our study illuminates the multifaceted aspects of ant-plant mutualisms and underscores the importance of evaluating costs and unexpected outcomes within these ecological relationships. Full article

(This article belongs to the Special Issue Plant–Animal Interactions: Exploring Costs and Benefits in Highly Conditional Relationships)

► Show Figures

Figure 1

16 pages, 2946 KiB

Open AccessEditor’s ChoiceArticle

Extrafloral Nectary-Bearing Plants Recover Ant Association Benefits Faster and More Effectively after Frost-Fire Events Than Frost

by Gabriela Fraga Porto, José Henrique Pezzonia and Kleber Del-Claro

Plants 2023, 12(20), 3592; https://doi.org/10.3390/plants12203592 - 17 Oct 2023

Viewed by 3419

Abstract

The Cerrado confronts threats such as fire and frost due to natural or human-induced factors. These disturbances trigger attribute changes that impact biodiversity. Given escalating climate extremes, understanding the effects of these phenomena on ecological relationships is crucial for biodiversity conservation. To understand [...] Read more.

The Cerrado confronts threats such as fire and frost due to natural or human-induced factors. These disturbances trigger attribute changes that impact biodiversity. Given escalating climate extremes, understanding the effects of these phenomena on ecological relationships is crucial for biodiversity conservation. To understand how fire and frost affect interactions and influence biological communities in the Cerrado, our study aimed to comprehend the effects of these two disturbances on extrafloral nectar (EFN)-bearing plants (Ouratea spectabilis, Ochnaceae) and their interactions. Our main hypothesis was that plants affected by fire would grow again more quickly than those affected only by frost due to the better adaptation of Cerrado flora to fire. The results showed that fire accelerated the regrowth of O. spectabilis. Regrowth in plants with EFNs attracted ants that proved to be efficient in removing herbivores, significantly reducing foliar herbivory rates in this species, when compared to the species without EFNs, or when ant access was prevented through experimental manipulation. Post-disturbance ant and herbivore populations were low, with frost leading to greater reductions. Ant richness and diversity are higher where frost precedes fire, suggesting that fire restores Cerrado ecological interactions better than frost, with less impact on plants, ants, and herbivores. Full article

(This article belongs to the Special Issue Plant–Animal Interactions: Exploring Costs and Benefits in Highly Conditional Relationships)

► Show Figures

Graphical abstract

10 pages, 1416 KiB

Open AccessArticle

Lutein and Zeaxanthin Content in 21 Plant Species from a Very Humid Premontane Forest in Colombia Palatable for Free-Range Laying Hens

by Yandy J. Aguillón-Páez and Gonzalo J. Díaz

Plants 2023, 12(19), 3484; https://doi.org/10.3390/plants12193484 - 5 Oct 2023

Viewed by 1212

Abstract

Xanthophylls, such as lutein and zeaxanthin, have several functions in both plants and humans, including detoxification of oxidants (reactive oxygen species (ROS) and other radicals), maintenance of the structural and functional integrity of biological membranes, and photoprotection from intense light damage. The objective [...] Read more.

Xanthophylls, such as lutein and zeaxanthin, have several functions in both plants and humans, including detoxification of oxidants (reactive oxygen species (ROS) and other radicals), maintenance of the structural and functional integrity of biological membranes, and photoprotection from intense light damage. The objective of the present study was to investigate the lutein and zeaxanthin content of 21 species of plants from a very humid premontane forest in Colombia during both dry and rainy seasons. The plants were selected based on being voluntarily eaten by laying hens under free-range conditions. Lutein and zeaxanthin were identified and quantified by high-performance liquid chromatography (HPLC). The results showed that all plants tested contained lutein, at levels ranging from 65.7 to 350 µg/g. Zeaxanthin levels were much lower (2.2 to 26.2 µg/lg) and were detected in only 5 of the 21 plants analyzed. Given that the lutein content of the plants tested in the present study was found to be comparable to that reported in marigold flowers (4–800 µg/g), it is possible that these plants can be used as a source of lutein in free-range laying hen production systems. Full article

(This article belongs to the Special Issue Plant–Animal Interactions: Exploring Costs and Benefits in Highly Conditional Relationships)

► Show Figures

Graphical abstract

17 pages, 2097 KiB

Open AccessArticle

Flowering Time Variation in Two Sympatric Tree Species Contributes to Avoid Competition for Pollinator Services

by Larissa Alves-de-Lima, Eduardo Soares Calixto, Marcos Lima de Oliveira, Letícia Rodrigues Novaes, Eduardo A. B. Almeida and Helena Maura Torezan-Silingardi

Plants 2023, 12(19), 3347; https://doi.org/10.3390/plants12193347 - 22 Sep 2023

Cited by 1 | Viewed by 3597

Abstract

Competition is an important biological filter that can define crucial features of species’ natural history, like survival and reproduction success. We evaluated in the Brazilian tropical savanna whether two sympatric and congenereric species, Qualea multiflora Mart. and Q. parviflora Mart. (Vochysiaceae), compete for [...] Read more.

Competition is an important biological filter that can define crucial features of species’ natural history, like survival and reproduction success. We evaluated in the Brazilian tropical savanna whether two sympatric and congenereric species, Qualea multiflora Mart. and Q. parviflora Mart. (Vochysiaceae), compete for pollinator services, testing whether there is a better competitor or whether plants present any anti-competitive mechanism. Additionally, we investigated the breeding system, pollinators, and flowering phenology of both species. The results showed that Q. multiflora and Q. parviflora are dependent on pollinators for fruit formation, as they exhibited a self-incompatible and non-agamospermic breeding system. These plants shared the same guild of pollinators, which was formed by bees and hummingbirds, and an overlap in the flower visitation time was observed. Each plant species had different pollinator attraction strategies: Q. multiflora invested in floral resource quality, while Q. parviflora invested in resource quantity. The blooming time showed a temporal flowering partition, with highly sequential flowering and no overlap. Qualea parviflora bloomed intensely from September to October, while Q. multiflora bloomed from November to January, with the flowering peak occurring in December. The two Qualea species have morphologically similar flowers, are sympatric, and share the same pollinator community, with overlapping foraging activity during the day. However, they do not compete for pollinator services as they exhibit an anti-competitive mechanism mediated by temporal flowering partition. Full article

(This article belongs to the Special Issue Plant–Animal Interactions: Exploring Costs and Benefits in Highly Conditional Relationships)

► Show Figures

Figure 1

16 pages, 1469 KiB

Open AccessArticle

Floral Aroma and Pollinator Relationships in Two Sympatric Late-Summer-Flowering Mediterranean Asparagus Species

by Leonardo Llorens, Joan Tomàs, Pere Ferriol, María Trinitat García and Lorenzo Gil

Plants 2023, 12(18), 3219; https://doi.org/10.3390/plants12183219 - 10 Sep 2023

Cited by 1 | Viewed by 1384

Abstract

This research delves into plant–pollinator relationships within the Mediterranean region, focusing on two synchronous and sympatric asparagus species: A. acutifolius and A. albus. For the first time, the floral scents of the genus Asparagus are reported. We investigate the volatile organic compounds [...] Read more.

This research delves into plant–pollinator relationships within the Mediterranean region, focusing on two synchronous and sympatric asparagus species: A. acutifolius and A. albus. For the first time, the floral scents of the genus Asparagus are reported. We investigate the volatile organic compounds (VOCs) present in their floral scents and their impact on pollinator attraction. Captured flower-emitted VOCs underwent solid-phase microextraction of headspace (SPME-HS) and gas chromatography and mass spectrometry (GC-MS) analysis. The investigation confirms distinctive aroma profiles for each species. A. albus predominantly emits benzene derivatives and sesquiterpenes, while A. acutifolius is characterized by carotenoid derivatives, monoterpenes, and sesquiterpenes. The only shared compounds between the two species are the sesquiterpenes (Z,E)-α-farnesene and (E,E)-α-farnesene. A positive correlation links peak floral aroma intensity (benzenoids in A. albus and ionones in A. acutifolius) with a higher pollinator visit frequency, emphasizing the critical role of intense floral scents in pollinator attraction. The study of reproductive aspects reveals almost complete gynodioecy in A. acutifolius, influencing unique dynamics for the two species. These adaptations hold significant importance within the Mediterranean ecosystem, particularly during the late dry summer period, when a limited number of plant species vie for a shared primary pollinator. Full article

(This article belongs to the Special Issue Plant–Animal Interactions: Exploring Costs and Benefits in Highly Conditional Relationships)

► Show Figures

Figure 1

10 pages, 276 KiB

Open AccessArticle

Measuring Bee Effects on Seed Traits of Hybrid Sunflower

by Gary J. Brewer, Kentaro Miwa and Kathryn Hanford

Plants 2023, 12(14), 2662; https://doi.org/10.3390/plants12142662 - 16 Jul 2023

Cited by 1 | Viewed by 1660

Abstract

In hybrid sunflower, bee pollination can improve productivity, but the contribution of bees to productivity may be over or underestimated. To estimate bee effects (seed trait gains from exposure to bees during anthesis), single capitula are commonly covered with a porous material to [...] Read more.

In hybrid sunflower, bee pollination can improve productivity, but the contribution of bees to productivity may be over or underestimated. To estimate bee effects (seed trait gains from exposure to bees during anthesis), single capitula are commonly covered with a porous material to exclude bees. However, depending on the exclosure porosity, estimates of the magnitude of bee effects will vary. In two studies, porosity size and bee effect gains in two sunflower types were tested. In the exclosure study, Delnet exclosures severely reduced seed set and exclosures with larger porosities and had smaller and similar effects. However, since a few small bees penetrated the largest porosity size tested, exclosures with porosity sizes < 7 mm are recommended. With an exclosure porosity of 5 X 5 mm, the estimated bee effect contribution to the yield was 323 kg per hectare. Effects of exclosures on seed traits were similar in the oilseed and confectionary hybrids tested. Insecticide use did not affect seed traits but did lower insect damage to seeds. Bees from three families, mostly Apidae, were collected while foraging on sunflower. In summary, we recommend the use of exclosures with porosities of about 3 to 5 mm to avoid over or underestimating bee effects. And we recommend holistic insect management for sunflower cropping systems that balances the benefits of bee effects on seed traits with management of pest insects. Full article

(This article belongs to the Special Issue Plant–Animal Interactions: Exploring Costs and Benefits in Highly Conditional Relationships)

Review

Jump to: Research

13 pages, 2230 KiB

Open AccessReview

Emerging Trends in Ant–Pollinator Conflict in Extrafloral Nectary-Bearing Plants

by Eduardo Soares Calixto, Isabela Cristina de Oliveira Pimenta, Denise Lange, Robert J. Marquis, Helena Maura Torezan-Silingardi and Kleber Del-Claro

Plants 2024, 13(5), 651; https://doi.org/10.3390/plants13050651 - 27 Feb 2024

Cited by 3 | Viewed by 2234

Abstract

The net outcomes of mutualisms are mediated by the trade-offs between the costs and benefits provided by both partners. Our review proposes the existence of a trade-off in ant protection mutualisms between the benefits generated by the ants’ protection against the attack of [...] Read more.

The net outcomes of mutualisms are mediated by the trade-offs between the costs and benefits provided by both partners. Our review proposes the existence of a trade-off in ant protection mutualisms between the benefits generated by the ants’ protection against the attack of herbivores and the losses caused by the disruption of pollination processes, which are commonly not quantified. This trade-off has important implications for understanding the evolution of extrafloral nectaries (EFNs), an adaptation that has repeatedly evolved throughout the flowering plant clade. We propose that the outcome of this trade-off is contingent on the specific traits of the organisms involved. We provide evidence that the protective mutualisms between ants and plants mediated by EFNs have optimal protective ant partners, represented by the optimum point of the balance between positive effects on plant protection and negative effects on pollination process. Our review also provides important details about a potential synergism of EFN functionality; that is, these structures can attract ants to protect against herbivores and/or distract them from flowers so as not to disrupt pollination processes. Finally, we argue that generalizations regarding how ants impact plants should be made with caution since ants’ effects on plants vary with the identity of the ant species in their overall net outcome. Full article

(This article belongs to the Special Issue Plant–Animal Interactions: Exploring Costs and Benefits in Highly Conditional Relationships)

► Show Figures

Figure 1

24 pages, 5596 KiB

Open AccessReview

Visual-, Olfactory-, and Nectar-Taste-Based Flower Aposematism

by Simcha Lev-Yadun

Plants 2024, 13(3), 391; https://doi.org/10.3390/plants13030391 - 29 Jan 2024

Cited by 1 | Viewed by 1734

Abstract

Florivory, i.e., flower herbivory, of various types is common and can strongly reduce plant fitness. Flowers suffer two very different types of herbivory: (1) the classic herbivory of consuming tissues and (2) nectar theft. Unlike the non-reversibility of consumed tissues, nectar theft, while [...] Read more.

Florivory, i.e., flower herbivory, of various types is common and can strongly reduce plant fitness. Flowers suffer two very different types of herbivory: (1) the classic herbivory of consuming tissues and (2) nectar theft. Unlike the non-reversibility of consumed tissues, nectar theft, while potentially reducing a plant’s fitness by lowering its attraction to pollinators, can, in various cases, be fixed quickly by the production of additional nectar. Therefore, various mechanisms to avoid or reduce florivory have evolved. Here, I focus on one of the flowers’ defensive mechanisms, aposematism, i.e., warning signaling to avoid or at least reduce herbivory via the repelling of herbivores. While plant aposematism of various types was almost ignored until the year 2000, it is a common anti-herbivory defense mechanism in many plant taxa, operating visually, olfactorily, and, in the case of nectar, via a bitter taste. Flower aposematism has received only very little focused attention as such, and many of the relevant publications that actually demonstrated herbivore repellence and avoidance learning following flower signaling did not refer to repellence as aposematism. Here, I review what is known concerning visual-, olfactory-, and nectar-taste-based flower aposematism, including some relevant cases of mimicry, and suggest some lines for future research. Full article

(This article belongs to the Special Issue Plant–Animal Interactions: Exploring Costs and Benefits in Highly Conditional Relationships)

► Show Figures

Figure 1

Journal Menu

Journal Browser

Plant–Animal Interactions: Exploring Costs and Benefits in Highly Conditional Relationships

Share This Special Issue

Special Issue Editor

Special Issue Information

Keywords

Benefits of Publishing in a Special Issue

Published Papers (16 papers)

Research

Review

Further Information

Guidelines

MDPI Initiatives

Follow MDPI