Bimodal Pollination by Wasps and Beetles in the African Milkweed <i>Xysmalobium undulatum</i>

Shuttleworth, Adam; Johnson, Steven D.

doi:10.1111/j.1744-7429.2008.00418.x

Cited by 34 publications

(23 citation statements)

References 25 publications

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“…The PTE for P. grandiflorus flowers was comparable to values recorded in other milkweed species (Ollerton et al . 2003; Shuttleworth & Johnson 2006, 2008, 2009a, 2009c, unpublished data). The percentage fruit set in P. grandiflorus , however, was remarkably high ( c. 14%) given that milkweeds typically exhibit very low levels of fruit set (Queller 1985; Lipow & Wyatt 1998).…”

Section: Discussionmentioning

confidence: 90%

“…This study adds another example to the growing list of South African plants that are reliant on Hemipepsis pompilid wasps for pollination (Ollerton et al . 2003; Johnson 2005; Shuttleworth & Johnson 2006, 2008, 2009a, 2009b, 2009c, Johnson et al . 2007; unpublished data).…”

Section: Discussionmentioning

confidence: 99%

“…Plants involved in this system include orchids (Johnson 2005; Johnson, Ellis & Dötterl 2007), milkweeds (Ollerton et al . 2003; Shuttleworth & Johnson 2006, 2008, 2009a, 2009c) and pineapple flowers (Hyacinthaceae: Eucomis ; Shuttleworth & Johnson 2009b). A general feature of these pompilid‐pollinated flowers is the production of exposed nectar with no morphological means to prevent non‐pollinator visits.…”

Section: Introductionmentioning

confidence: 99%

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The importance of scent and nectar filters in a specialized wasp‐pollination system

Shuttleworth

Johnson²

2009

Functional Ecology

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Summary 1.Plants with open flowers and exposed nectar should attract a wide diversity of flower visitors, yet, for reasons that are not yet well understood, some plants with these 'generalist' floral traits have highly specialized pollination systems. 2. We investigated this problem in the African milkweed Pachycarpus grandiflorus which has open flowers that produce copious amounts of exposed and concentrated nectar, yet is visited almost exclusively by spider-hunting wasps in the genus Hemipepsis . 3. These wasps were the only visitors found to consistently carry pollinaria and a cage experiment showed that they are capable of successfully pollinating this plant. Furthermore, experimental hand-pollinations showed that P. grandiflorus is genetically self-incompatible and thus reliant on pollinators for seed set. 4. We investigated the roles of chemical (nectar and floral scent) and spectral properties in the selective attraction of wasps and the filtering out of other potential flower visitors. Nectar palatability experiments showed that the nectar is unpalatable to honeybees but palatable to the wasps. Choice experiments conducted in the field and using a Y-maze in the laboratory showed that wasps are attracted primarily by scent rather than visual cues. Analysis of scent using Gas Chromatography-Mass Spectrometry showed that these inflorescences produce 36 different compounds, mostly monoterpenes and aliphatics. Analysis of spectral reflectance showed that flowers have similar colouring to the background vegetation. 5. We conclude that P. grandiflorus is specialized for pollination by Hemipepsis wasps, and in the absence of morphological filters, achieves specialization through unpalatable nectar, cryptic colouring and scent as a selective pollinator attractant. 6. This study demonstrates that plants whose flowers are not morphologically adapted to exclude particular floral visitors can achieve specialization through non-morphological filters.

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Section: Discussionmentioning

confidence: 90%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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The importance of scent and nectar filters in a specialized wasp‐pollination system

Shuttleworth

Johnson²

2009

Functional Ecology

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“…Predominantly, insect-pollinated species have different degrees of specialization depending on the insects involved (Aigner 2001;Shuttleworth and Johnson 2008). Therefore, features such as floral color and symmetry play a key role in plant-pollinator systems (Giurfa et al 1999;Cooley et al 2008).…”

Section: Do Generalist Insect Pollinators Serve Weeds Better? Not Alwaysmentioning

confidence: 99%

Weed-insect pollinator networks as bio-indicators of ecological sustainability in agriculture. A review

Rollin¹,

Benelli

Benvenuti

et al. 2016

Agron. Sustain. Dev.

101

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The intensification of agricultural practices contributes to the decline of many taxa such as insects and wild plants. Weeds are serious competitors for crop production and are thus controlled. Nonetheless, weeds enhance floral diversity in agricultural landscapes. Weeds provide food for insects in exchange for pollination. The stability of mutualistic interactions in pollination networks depends on conservation of insect pollinator and weed communities. Some agricultural practices can destabilize interactions and thus modify the stability of pollination networks. Therefore, more knowledge on weed-insect networks is needed. Here, we review the interactions involved in insect visits to weed flowers in temperate arable lands. Our main findings are that (1) weed pollination by insects has a key role in maintaining weed communities in arable lands; (2) weed-insect pollinator interactions are modulated by the flowers' features and their quality which are attracting insects; (3) most weeds are associated with generalist insect pollinators; and (4) even if weed-pollinator networks are largely mutualistic, some antagonist networks can be observed when deception occurs. We propose three weed-insect pollinator networks as potential bio-indicators to evaluate the ecological sustainability of arable land management strategies in temperate areas: (1) Geometridae and Bombyliidae species visiting Caryophyllaceae, (2) Papilionidae foraging on Apiaceae, and (3) Syrphidae visiting Asteraceae.

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“…However, floral syndromes are not always clear-cut, especially in plants that have generalist pollination systems or straddle two different pollination systems (Manning & Goldblatt 2005;Shuttleworth & Johnson 2008). Ollerton et al (2009) recently scored binary traits in flowers in combination with floral visitors in several communities, including one in eastern South Africa, and found that combinations of these traits for individual species seldom coincide with classical floral syndromes.…”

Section: Pollination Systems As Nichesmentioning

confidence: 99%

The pollination niche and its role in the diversification and maintenance of the southern African flora

Johnson

2010

Phil. Trans. R. Soc. B

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243

232

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The flora of southern Africa has exceptional species richness and endemism, making it an ideal system for studying the patterns and processes of evolutionary diversification. Using a wealth of recent case studies, I examine the evidence for pollinator-driven diversification in this flora. Pollination systems, which represent available niches for ecological diversification, are characterized in southern Africa by a high level of ecological and evolutionary specialization on the part of plants, and, in some cases, by pollinators as well. These systems are asymmetric, with entire plant guilds commonly specialized for a particular pollinator species or functional type, resulting in obvious convergent floral evolution among guild members. Identified modes of plant lineage diversification involving adaptation to pollinators in these guilds include (i) shifts between pollination systems, (ii) divergent use of the same pollinator, (iii) coevolution, (iv) trait tracking, and (v) floral mimicry of different model species. Microevolutionary studies confirm that pollinator shifts can be precipitated when a plant species encounters a novel pollinator fauna on its range margin, and macroevolutionary studies confirm frequent pollinator shifts associated with lineage diversification. As Darwin first noted, evolutionary specialization for particular pollinators, when resulting in ecological dependency, may increase the risk of plant extinction. I thus also consider the evidence that disturbance provokes pollination failure in some southern African plants with specialized pollination systems.Keywords: adaptive radiation; coevolution; mutualism; pollination ecotypes; pollination syndrome; speciationResearch in these fields [pollination and dispersal biology] is going to be the most fruitful approach to understanding evolutionary trends in higher plants. (Stebbins 1970)

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Bimodal Pollination by Wasps and Beetles in the African Milkweed Xysmalobium undulatum

Cited by 34 publications

References 25 publications

The importance of scent and nectar filters in a specialized wasp‐pollination system

The importance of scent and nectar filters in a specialized wasp‐pollination system

Weed-insect pollinator networks as bio-indicators of ecological sustainability in agriculture. A review

The pollination niche and its role in the diversification and maintenance of the southern African flora

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