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A tripped and untripped flower of D. setigerum (above, photo DS), and a small solitary bee (Lasioglossum/Pseudapis sp.) foraging at tip of keel complex in untripped D. setigerum; an illegitimate visit that does not trigger explosive pollen release (below, photo CN).
Source publication
Explosive pollen release is documented in many plant families, including the Fabaceae. Desmodium setigerum E. Mey (Fabaceae) is a perennial herb with single trip explosive pollen release found in eastern Africa, and the unique ability to reverse floral colour change if insufficient pollination has occurred. However, little else is known about the p...
Contexts in source publication
Context 1
... & Cocucci 2011;Stout 2000;Vivarelli et al. 2011), detailed information is still required on how different visitors and visitor size might affect various aspects of plant reproductive fitness in flowers of this type. J Poll Ecol 19 (7) Desmodium setigerum E. Mey. is a common, scrambling perennial found in disturbed areas throughout eastern Africa (Fig. 1). It has typical papilionate legume flowers that last a single day and 'trip' explosively when visited, with the keel petals remaining open and the filaments and gynoecium remaining uncovered. Unusually for species with flowers that only last a day (Van Doorn 1997), D. setigerum displays rapid floral colour change following visitation. ...
Context 2
... observations indicated that not all bees were able to effect explosive pollen release; some small Lasioglossum/Pseudapis solitary bees (ca. 6-8 mm estimated body length from head to tip of abdomen) foraged for pollen at the tip of the keel petals rather than attempting to access nectar at the base of the flag ( Fig.1; these bees were classed as "illegitimate visitors" and are not included in further analyses). ...
Similar publications
This study aims to understand the role of floral traits in determining the pollination and reproduction of Desmodium grahamii (Fabaceae, Papilionoideae) with explosive floral mechanism in populations occurring in a natural reserve and botanical garden in southern Mexico City. We assessed the breeding system by quantifying floral and pollinator acti...
Citations
... In flowers with 2PP, pollen follows a longer path from anther dehiscence to pollen transfer, relative to flowers with primary Nascimento et al. 2018 Cannaceae (1) 1 (Canna) Style Deposition Stiles and Freeman 1993;Yeo 1993;Ladd 1994;Glinos and Cocucci 2011;Maruyama et al. 2015 Pump, brush, deposition Arroyo 1981; Lavin and Delgado 1990;Yeo 1993;Westerkamp 1997;Westerkamp and Weber 1999;Etcheverry et al. 2008Etcheverry et al. , 2012aEtcheverry et al. , 2012bGalloni et al. 2007;Willmer et al. 2009;Delgado-Salinas et al. 2011;Alemán et al. 2014;Stanley et al. 2016;Fleming and Etcheverry 2017;Etcheverry and Vogel 2018 Polygalaceae (29) 3 Style Pump, deposition Yeo 1993;Ladd 1994;Westerkamp 1997;Westerkamp and Weber 1999;Castro et al. 2008aCastro et al. , 2008bDe Kock et al. 2018;Uluer et al. 2022 Malpighiales: Rhizophoraceae ( Rosids-malvids clade: ...
... Although this form of pollen transfer is usually irreversible, there may be some exceptions, such as that described in Desmodium setigerum E. Mey. (Willmer et al. 2009;Stanley et al. 2016). ...
... For flowers that also produce other floral rewards (nectar, oils, scents), several recent studies have evidenced that the body size of floral visitors is related to their ecological function, or pollen deposition or a foraging behavior that favors cross-pollen flow (Willmer and Finlayson, 2014;Jauker et al., 2016;Stanley et al., 2016;Baronio et al., 2020;Morais et al. 2020). In most of these studies, bees of large body size were associated with greater efficiency as pollinators (Stout, 2007;Willmer and Finlayson, 2014;Jauker et al., 2016;Baronio et al., 2020;Morais et al., 2020). ...
Premise:
Flowering plants with poricidal anthers are commonly visited by buzzing bees, which vibrate flowers to extract pollen. However, not all flower visitors are in fact pollinators, and features such as body size and duration of flower visits are important factors in determining pollination effectiveness. We tested whether bee-to-flower size relationships predict the pollination effectiveness of flower visitors of a buzz-pollinated species (Chamaecrista ramosa, Fabaceae).
Methods:
We sorted 13 bee taxa into three groups: smaller than, equivalent to ("fit-size"), and larger than flower herkogamy (spatial separation between anthers and stigma). We expected the latter two groups to touch the stigmas, which would be an indicator of pollination effectiveness, more frequently than the first group. To test this hypothesis, we assessed contact with stigmas, foraging behavior, and duration of visits for the three size groups of bees.
Results:
Our data reveal that small bees scarcely touched the stigmas, while large and fit-size bees were the most efficient pollinators, achieving high stigma-touching rates, conducting much shorter flower visits, and visiting flowers and conspecific plants at high rates during foraging bouts.
Conclusions:
The results did not show size-matching among bees and flowers, as expected, but rather a minimum size threshold of efficient pollinators. The finding of such a threshold is a nonarbitrary approach to predicting pollination effectiveness of visitors to herkogamous flowers with poricidal anthers.
... The current literature review on the pollination biology of keel flowers showed that many bee species move freely between small and large flowers. In this case, it is possible that rather than only the bee size, other characteristics of the pollinators such as optimum size of the bees (Stout, 2000;Stanley et al., 2016;de Souza et al. 2017), strength (Córdoba & Cocucci, 2011, handling type (Stanley et al., 2016), constancy (Gumbert & Kunze, 1999;Gegear & Laverty, 2005), flower colour (Raine & Chittka, 2007;Peter & Johnson, 2008), bee fauna (Gross, 2001;Bernhardt et al., 2008), environmental conditions such as temperature (Parker et al., 2002) and pollination mechanisms of Papilionoideae (valve, pump, explosive and brush, e.g., Westerkamp, 1997) may be also important or bee preferences. For example, it was observed that the legume-loving megachilids commonly move between both small and large Collinsia flowers at least if the flowers have somewhat similar colour and plants themselves can support their weight (Scott Armbruster, personal observation). ...
... The current literature review on the pollination biology of keel flowers showed that many bee species move freely between small and large flowers. In this case, it is possible that rather than only the bee size, other characteristics of the pollinators such as optimum size of the bees (Stout, 2000;Stanley et al., 2016;de Souza et al. 2017), strength (Córdoba & Cocucci, 2011, handling type (Stanley et al., 2016), constancy (Gumbert & Kunze, 1999;Gegear & Laverty, 2005), flower colour (Raine & Chittka, 2007;Peter & Johnson, 2008), bee fauna (Gross, 2001;Bernhardt et al., 2008), environmental conditions such as temperature (Parker et al., 2002) and pollination mechanisms of Papilionoideae (valve, pump, explosive and brush, e.g., Westerkamp, 1997) may be also important or bee preferences. For example, it was observed that the legume-loving megachilids commonly move between both small and large Collinsia flowers at least if the flowers have somewhat similar colour and plants themselves can support their weight (Scott Armbruster, personal observation). ...
The evolution of keel flowers within Fabaceae, Polygalaceae and some other clades of angiosperms is attributed to skilled and strong bees. However, whether this is true or not, is still an open question. Therefore, the literature is surveyed for the Hymenopteran pollinators of keel flowers, for 119 sources and for 112 species, six genera and two tribes for five characters which are the size of the flowers, Hymenopteran flower visitors/pollinators, size of the Hymenopteran pollinators, pollen and nectar robbers/thieves and size of the Hymenopteran thieves/robbers. The results suggest that Fabales keel flowers are mainly pollinated by long-tongued bees, from Apidae and Megachilidae families; and the most common pollinators of the keel flowers are small Megachile and Osmia; medium-sized Apis, Anthophora and Eucera; and large Xylocopa, Bombus and Centris. While the literature suggests that keel flowers are pollinated by skilled and strong bees, the results of the current review have shown that this is not the whole case in terms of flower size and bee size. There is no difference between pollinator diversity and flower size. While floral robbers/thieves are mostly up to 2 cm, among them honey-bees (Apis mellifera) both pollinate and rob the keel flowers. Keel flowers of Polygalaceae and other angiosperm lineages are somehow similar to the keel flowers of Papilionoideae.
... Previous pollination studies of Desmodium demonstrate that a change in the colour and position of the petals is associated with the explosive mechanism. It has also been shown that bees of different sizes, ranging from mediumsize Megachile to large-size Xylocopa species, are the only floral visitors capable of activating/triggering the pollination mechanism (Arroyo 1981;Willmer et al. 2009;Córdoba and Cocucci 2011;Alemán et al. 2014;Stanley et al. 2016;Figueroa-Fleming and Etcheverry 2017). For most of the studied species where secondary presentation of pollen has been attributed, pollen has been identified as the only reward offered to pollinators (Yeo 1993;Etcheverry et al. 2012;Alemán et al. 2014). ...
... For most of the studied species where secondary presentation of pollen has been attributed, pollen has been identified as the only reward offered to pollinators (Yeo 1993;Etcheverry et al. 2012;Alemán et al. 2014). Many of the species have been confirmed as being self-compatible, although the capability of self-pollination appears to be species-dependent (Hutton 1960;Alemán et al. 2014;Stanley et al. 2016). ...
... A single Megachile bee may visit up to 20 open flowers in the course of a single foraging bout, and typically bear pollen mostly of D. grahamii, showing that flowers are dependent on these bees for the transfer of pollen from one flower to another, and bee visitation is generally equated with flower pollination (Tables 1, 2). This effectiveness was also found in the pollination of D. setigerum in Uganda, where a species of Megachile bee deposited more pollen on the flower stigma than any other of the 15 pollinators tested (Stanley et al. 2016). Furthermore, the Megachile bees show flower constancy, repeating visitations to flowers of the same type while ignoring other rewarding flowers nearby, thus improving handling time and flight distances between flowers. ...
This study aims to understand the role of floral traits in determining the pollination and reproduction of Desmodium grahamii (Fabaceae, Papilionoideae) with explosive floral mechanism in populations occurring in a natural reserve and botanical garden in southern Mexico City. We assessed the breeding system by quantifying floral and pollinator activity, compatibility, pollination, and reproductive success, assisted by field and laboratory analyses. Results showed that cross-pollination and self-pollination coexist, but bees are required for fruit and seed set. Flower colour is the primary attractant. Floral scent is also likely important because the petals were covered with papillae, although no scent was perceptible. Morphological and functional observations of D. grahamii exhibit simultaneous pollen release and stigma receptivity when the flower is activated by a pollinator and there is no secondary pollen presentation; this contrasts with what has been reported on other species of Desmodium. Pollen is the pollinators’ only reward, and its deposition and collection must be done synchronically, occurring when a bee lands and introduces its proboscis in the flower. In this study, we identified seven floral visitors: five bee pollinators and two syrphid flies as pollen thieves. On some occasions, Apis mellifera also behaves as a pollen thief. Fruit and seed set of flowers that were isolated from visitors may indicate a delayed pollination mechanism. Pollination results also suggest that Apis bees and syrphid flies may contribute to fruit and seed production when they forage on flowers at post-anthesis.
... Como consequência da sinalização visual com o aumento do display, as plantas receberiam mais visitas (Ohashi et al. 2015) e poderiam reduzir a geitonogamia (isto é, transferência de pólen entre flores de um mesmo indivíduo) ao minimizar visitas de abelhas a flores não-receptivas em sinalizações honestas (Schlindwein et al. 2014). No entanto, um estudo com Desmodium setigerum (Fabaceae) mostrou que esta espécie tem a habilidade de reverter seus sinais de mudança de coloração e até mesmo a forma de suas flores quando sofrem limitação polínica (Stanley et al. 2016). Este mecanismo possibilita que as flores que não foram adequadamente polinizadas tenham uma nova chance nesse processo, atraindo outros polinizadores (Willmer et al. 2009). ...
HOW DO BEES PERCEIVE FLOWERS AND WHY IT IS IMPORTANT?
Animal cognition can be defined as the ability of an organism to acquire, retain and subsequently use the sensory information during decision-making processes in different contexts. The understanding of how the signals emitted in the environment interact with the sensory system of animals capable of perceiving them helps to unravel the ecological and evolutionary significance of the interactions between organisms. In the context of pollination, the attraction of visitors to the flower is attributed to a great diversity of signals, especially visuals and olfactory. In addition to acting as attractants, they can also exhibit functions related to the communication of the presence/absence of resources. Nevertheless, other sensory modalities, also play a relevant role on the interaction between flowers and visitors. The central idea of the present study is to present, through relevant examples from the literature, the main signals emitted by the flowers and perceived by the bees, either by a single sensory modality or through multiple modalities. Regardless of the
sensory modality and the complexity of the stimuli, studies of the interactions between plants and their floral visitors can be better understood and detailed if we consider the different aspects related to the signal being emitted and the directionality of the same, or simply the capacity or not to be perceived. Quantifying processes, their causes and consequences reinforce the understanding of volutionary,
ecological and behavioral patterns among interacting organisms, both in mutualistic and antagonistic relationships.
Keywords: cognition; floral attractants; plant-pollinator interaction; pollinators; sensory systems.
... Có rdoba and Cocucci (2017) found that bumblebees and megachilids were the most important pollinators to the four keel flower species they studied, and that more stiff flowers were visited by a diverse set of strong (large) bees. Although larger bees are not always more effective pollinators of keel flower species (see Stanley et al. [2016] regarding pollination of a Desmodium species, and Stout (2000) reporting on pollination of a Cytisus species), Willmer and Finlayson (2014) reported positive effects of individual bee size on singlevisit pollen deposition amounts in the nonkeel flowers of Vinca minor L. (Apocynaceae). ...
Apios priceana B. L. Rob. is federally threatened and little is known about its pollination biology. At the Redstone Arsenal population, Alabama, we studied its breeding system, determined major floral visitors and their pollination effectiveness, and explored pollen limitation of fruit and seed production. Fruit initiation was low (3.9%) for cross-pollinated flowers but only marginally greater than for self-pollinated or nonpollinated flowers (none initiated a fruit). Most floral visits (97%) were by bees with 43% of visits by large bees (> 1.5 cm in length) and 51% by medium bees (1-1.5 cm in length). Keel petals of A. priceana flowers enclose the style and stamens: flowers must be "tripped" for pollination to occur. Large and medium bees were equally effective in tripping flowers, whereas small bees (< 1 cm in length) did not trip flowers. Success of large and medium bee species (several Bombus species and Megachile sculpturalis Smith) in initiating legumes after a single floral visit ranged from 17-35% but did not differ significantly among species. Pollen supplementation showed legume production was pollen-limited: 24% of supplemented flowers produced fruits versus 6% of nonsupplemented flowers. Seed counts revealed a marginally nonsignificant trend for more seeds in legumes from pollen-supplemented flowers. We conclude that this rare plant species is dependent on medium and large bees for pollination, and that reproduction is partially pollen-limited. Conservation efforts should include measures to protect bee pollinators of this species to ensure that managed populations of this rare plant continue to reproduce sexually.
... Consequently, once the reproductive column comes into contact with the insect body for the first time, the wing-keel complex cannot return to its original position and the explosive mechanism gets deactivated (Arroyo 1981;Yeo 1993;Westerkamp 1997;López et al. 1999;Galloni and Cristofolini 2003;Galloni et al. 2007;Alemán et al. 2014). However, it was observed in flowers of D. setigerum that floral parts partially return to their original positions after the first visit (Willmer et al. 2009;Stanley et al. 2016), and the same situation was reported in other legume species with this mechanism (López et al. 1999;Galloni and Cristofolini 2003;Solomon Raju and Purchandra Rao 2006). The mechanism is activated if a given threshold strength is reached due to the action of an animal visiting the flower (Suzuki 2003;Solomon Raju and Purchandra Rao 2006;Córdoba and Cocucci 2011). ...
... However, they deposited a smaller percentage of pollen in species with pump mechanism. Recently it was found that one species of Megachile deposited more pollen per single visit (>250) than most other visitors in explosive flowers of D. setigerum (Stanley et al. 2016). The reasons for their success in pollen deposition are related to pollencarrying hairs on the underside of the abdomen, potentially making visitors more likely to deposit pollen when positioning themselves on the keel of flowers. ...
... The reasons for their success in pollen deposition are related to pollencarrying hairs on the underside of the abdomen, potentially making visitors more likely to deposit pollen when positioning themselves on the keel of flowers. The other reason is a morphological "fit" (or size matching) for achieving contact with the reproductive parts of flowers (Stanley et al. 2016). These results, together with those obtained in the present study, reinforce the idea that papilionate flowers with an explosive mechanism are more specialized in terms of its flower visitors than usually assumed for papilionate flowers (Stanley et al. 2016). ...
The pump pollination mechanism is typical of basal clades within Papilionoideae and might be associated with less efficient pollen transfer systems, while the explosive tripping mechanism is considered more advanced and might represent the highest expression of the trend in pollen economy. Crotalaria pumila, C. stipularia, Desmodium incanum and D. subsericeum present secondary pollen presentation with pump and explosive pollination mechanisms, respectively. In the present study, we evaluate and compare (1) pollen removal, (2) pollen deposition and (3) pollen transfer efficiency of both mechanisms, considering single visits by Megachile spp., common pollinators of the four plant species in Salta Province, Argentina. Comparisons of visit durations are made in relation to the type of mechanism and rewards offered. We detected significant differences between both mechanisms in the proportion of pollen grains removed and deposited in a flower after a single visit of Megachile. We found that efficiency in pollen transfer was significantly higher for explosive mechanism (2.13 ± 0.42 pollen grains deposited per 100 removed) than for pump mechanism (0.33 ± 0.17 pollen grains deposited per 100 removed). This is the first study that compares efficiency between pollination mechanisms in this group of plants.
