Please read the abstract (Summary) in the section, 09summary and aknowledgements, of this document / Dissertation (MSc (Entomology))--University of Pretoria, 1988. / Zoology and Entomology / MSc / unrestricted

Thesis (MSc (Botany and Zoology))--University of Stellenbosch, 2010. / ENGLISH ABSTRACT: It is thought that a large proportion of the great variety of floral structures in flowering plants reflect adaptations to different biotic pollen vectors. Divergence in flower traits and pollinators is linked to speciation. Pollinator-driven speciation is thought to have played a large role in the spectacular floral diversity found in South African Iridaceae and the genus Tritoniopsis is a particularly good example of this. This study focuses on Tritoniopsis revoluta, a pink irid occurring in the Swartberg and Langeberg Mountains, as well as Potberg Mountain. I tested the hypothesis that variation in flower tube-lengths of Tritoniopsis revoluta are related to the geographic distribution of pollinators and the variation of their tongue lengths. It was determined that this species is highly variable in respect to corolla tube-length and is pollinated by different fly species across its range. Also, the tongue-lengths of the fly pollinators corresponded almost exactly with the tube-length of the flowers they were pollinating in each population. In some populations, where long-proboscid flies were absent, bees were observed visiting T. revoluta flowers. This presents evidence for pollinator-driven floral variation within a single plant species, and most of this vast diversification in floral morphology has probably been driven by morphological variation found within a single fly family. In one population I found variable tube-lengths which appeared to exhibit a bimodal distribution of corolla tubelengths. I hypothesized that the two Tritoniopsis revoluta ecotypes at this population are pollinated by two different pollinators, leading to assortative mating, and ultimately strong inter-ecotype incompatibility. Tritoniopsis revoluta is self-incompatible and exists as two discrete entities (morphotypes) at the Gysmanshoek Pass site, and these entities differ in tubelength, color, nectar volume and sugar content. These morphotypes were not pollinated by long-proboscid flies, but seems to represent a recent shift to pollination by Amegilla bees. However, ecotypes are not reproductively isolated as short and long flowers can produce offspring, rather tube-length differences are possibly maintained through spatial separation. To compliment the correlatory data between flower tube-lengths and pollinator tongue-lengths, I used molecular tools (chloroplast markers and AFLPs) to elucidate the patterns of tube-length evolution in Tritoniopsis revoluta. I aimed to determine the directionality and frequency of transitions between tube-length categories. Tube-length transitions would be suggestive of flower morphology being labile, and together with the tube-tongue length correlation it suggests pollinator shifts may drive the changes in tube length. Character state reconstructions using tube-length as character determined that four evolutionary transitions to shorter tube-length categories and two transitions to longer categories occurred. I also tested whether morphological divergence between populations corresponds to patterns of divergence from neutral genetic markers. Population genetic structure in this system showed that the different populations of T. revoluta are vicariant and tube-length differences between them could have evolved through selection. / AFRIKAANSE OPSOMMING: Dit is ‘n algemene gedagte dat die groot verskeidenheid blom strukture in die angiosperme dui op aanpassings tot verskillende biotiese stuifmeel draers. Die diverse blom strukture in baie van die groot Kaapse genera kan verduidelik word deur aanpassings tot veranderinge in bestuiwings-sisteme. ‘n Aantal studies hieroor stel voor dat bestuiwers nie net die veranderinge in blom morfologie bewerkstellig nie, maar ook ‘n rol speel in die aanpassende uiteenlopendheid van blomplant kenmerke. Spesiasie bewerkstellig deur bestuiwers het moontlik ‘n groot rol gespeel in die blom-diversiteit wat gevind word in die Suid-Afrikaanse Iridaceae familie, en die genus Tritoniopsis is ‘n baie goeie voorbeeld hiervan. Hierdie studie fokus spesifiek op Tritoniopsis revoluta, ‘n pienk iris wat voorkom in die Swart- en Langeberge, asook by Potberg. Die hipotese dat die variasie in buis-lengtes van T. revoluta verwant is aan die geografiese verspreiding van bestuiwers en die variasie in hul tong-lengtes is hier getoets. Dit is bepaal dat hierdie spesie groot variasie toon in terme van buis-lengtes en bestuif word deur verskillende vlieg spesies regoor sy verspreiding. Die tong-lengtes van hierdie vlieë korrespondeer ook met die buis-lengtes van die blomme wat hul bestuif in elkeen van die T. revoluta populasies. In sommige van die populasies, waar lang-tong vlieë afwesig was, is bye wat die T. revoluta blomme besoek, opgemerk. Hierdie resultate lewer bewyse vir die hipotese dat bestuiwers blom morfologie kan beïnvloed; die interessante hiervan is dat die variasie in buis-lengtes in hierdie spesie heel moontlik te danke is aan die morfologies variasie wat gevind word in ‘n enkele lang-tong vlieg familie. In een van die populasies het ek ‘n bimodale verspreiding van buis-lengtes gevind. ‘n Logiese afleiding is dat hierdie twee verskillende buislengtes – ekotipes – deur twee verskillende bestuiwers besoek word, en dat dit lei tot sterk onversoenbaarheid tussen ekotipes. Tritoniopsis revoluta is nie instaat tot self-bestuiwing nie en die twee ekotipes verskil in terme van buis-lengtes, kleur, nektar volume en suiker inhoud. Kort- en lang-buis blomme word nie eksklusief bestuif deur lang-tong vlieë in die Gysmanshoek Pas nie, maar word in die algemeen ook bestuif deur bye van die genus Amegilla. Die twee ekotipes is in staat om te reproduseer met mekaar, so die buis-lengte verskille word moontlik in stand gehou deur hul geografiese skeiding. Om die korrelasie analise tussen blom buislengtes en vlieg tong-lengtes te komplimenteer, het ek molekulêre tegnieke (chloroplast merkers en AFLPs) gebruik om die patrone van buis-lengte evolusie in Tritoniopsis revoluta duidelik te maak. Ten eerste het ek bepaal of verkortings en verlengings van buis-lengtes een keer in die verlede gebeur het, of as meermalige gebeurtenisse. Meermalige veranderinge in buis-lengtes kan moontlik dui op verskuiwings tussen verskillende bestuiwers, asook taksonomiese verdelings wat korrespondeer met bestuiwer veranderinge. Ek het ook bepaal of die buis-lengte verskille in die verskillende populasies toegeskryf kan word aan seleksie prosesse. Deur buis-lengte as karakter te gebruik, het ek karakter-status rekonstruksies gedoen en bepaal dat vier ewolutionêre transisies na korter buis-lengte kategorieë, en twee transisies na langer kategorieë plaasgevind het. Populasie genetiese struktuur in die sisteem dui daarop dat T. revoluta populasies geïsoleer is deur afstand. Die konklusie wat ek trek gebasseer op hierdie resultate is dat verskille in buis-lengtes in hierdie sisteem moontlik ontstaan het as gevolg van die verskillende bestuiwers wat aktief is in die verskillende T. revoluta populasies, en dat natuurlike prosesse nie die hoofrol spelers in hierdie sisteem is ten opsigte van buis-lengte evolusie nie.

Thesis (PhD)--Stellenbosch University, 2013. / Pollinators play a fundamental role in floral evolution. They can exert selection on the flowers they visit in a plethora of different ways, ranging from innate floral preferences to differences in body size and shape and behavioural elements such as flower constancy and learning capacity. Since different pollinators exhibit differences in these characters, shifts between pollinating species are often considered the most likely drivers of floral diversification. While many lines of evidence support this claim, numerous angiosperms pollinated by a single species also exhibit floral variation. Throughout my thesis, I explore and investigate floral diversification in such species in the absence of pollinator shifts. In Chapter 2, I investigate variation in the preference of conspecific male and female pollinators for the floral traits of a sexually deceptive daisy that comprises distinct floral forms. I show that its pollinator exhibits gender-specific variation in floral preferences, and that some floral forms have specialized on the male pollinator. This chapter thus illustrates the importance of intraspecific variation in pollinator preference for floral diversification, an underappreciated mechanism in this field of research. The innate preferences of pollinators are likely to have a genetic basis, especially innate preferences that govern mate choice. Genetic structure within the pollinators of sexually deceptive plants, which mimic female insects to achieve pollination, may thus provide an important source of selection on the plants they pollinate. This depends on an association between genetic divergence and divergent mate preferences, and I explore this intriguing idea in Chapter 3. While pollinators associated with sexually deceptive floral forms did exhibit significant genetic structuring, male pollinators from different phylogeographic clades all exhibited preference for the same sexually deceptive floral form, thus rejecting this hypothesis. Another behavioural attribute of pollinators that may affect floral evolution, particularly in deceptive plant species, is learning ability. Studies on sexually deceptive orchids often report that male pollinators tend to avoid sexually deceptive flowers with experience. In Chapter 4, I systematically investigate learning abilities within male pollinators and the costs they suffer on sexually deceptive floral forms that vary in deceptiveness. Results reveal a positive relationship between the level of floral deceptiveness and the 4 associated mating costs that deceived males suffer. Pollinator learning, however, appears to occur only on the most deceptive floral forms, suggesting a link between the costs suffered to the occurrence of learning. In Chapter 4, I systematically investigate learning abilities within male pollinators and the costs they suffer on sexually deceptive floral forms that vary in deceptiveness. Results reveal a positive relationship between the level of floral deceptiveness and the associated mating costs that deceived males suffer. Pollinator learning, however, appears to occur only on the most deceptive floral forms, suggesting a link between the costs suffered to the occurrence of learning. In Chapter 5, I explore the importance of florivory damage in a polymorphic daisy. Studies on floral evolution often overlook the significance of florivorous visits and focus only on pollinator-mediated selection. I show that floral polymorphism is maintained by antagonistic selection exerted by pollinators and florivores on the same floral traits. Lastly, I focus on evolutionary history to explore similarity in the patterns of South African angiosperm evolution and the pollinator species used throughout my thesis. Molecular dating shows this pollinator exhibits broadly congruent evolutionary patterns to these angiosperms, indicative of a shared biogeography. Taken together, my thesis demonstrates the vast impact of floral visitors, in particular pollinating insects, on the evolution of floral form. / My research was funded by the National Research Foundation of South Africa (NRF) and personal funding was provided by a NRF Innovation scholarship and merit bursaries from the Botany and Zoology department at Stellenbosch University. A WhiteSci Travel Grant and financial support from Prof. Erik Svensson at Lund University also allowed me to present parts of my research at international conference.

Thesis (MSc)--Stellenbosch University, 2015. / ENGLISH ABSTRACT: The present global biodiversity crisis is characterized mostly by loss of species due to habitat destruction but there other major threats – notably invasive alien species. The term “biodiversity hotspot” has been coined to emphasize areas for conservation prioritization – areas that have high biodiversity under threat from habitat destruction, invasive species, etc. The Cape Floristic Region (CFR) in the Western Cape (WC) Province of South Africa has the highest biodiversity of all Mediterranean-type climate regions globally and is classified among global biodiversity hotspots. The CFR, a Mediterranean-type climate heathland with a naturally high fire frequency, faces threat from transformation by development, disturbed (increased) fire frequencies and intensities, and invasive organisms, most notably invasive trees. Such threats disturb keystone species and keystone processes including insect pollinator assemblages and associated insect flower visitation webs and frequencies. Invasive pines are a serious threat to insect flower visitation as pine trees (Pinus spp.) shade out much indigenous vegetation in the CFR. Little is known of their long-term effects on insect flower visitors and vegetation recovery in post-pine restoration and recovery areas after such trees are removed. I investigated the recovery of vegetation and the most important insect pollinator, bees, after the removal of pines by fire and passive recovery in a CFR valley in the Western Cape. In 1999, a wildfire burned much of the WC Limietberg Nature Reserve along with an adjacent pine tree forestry stand - which was then left to recover, providing an ideal opportunity to investigate the enduring effects of pine afforestation in the CFR. In two data chapters, I compared the post-fire passive recovery of vegetation (Chapter 2) and bee diversity (Chapter 4) in areas which had previously been planted with pines vs. those which had contained natural fynbos. To improve on sampling methodology, I conducted an experiment that demonstrated the Observer Effect in bee sampling with a sweep net (Chapter 3), and I developed a novel sampling device (Chapter 5) for insect flower visitors. Sampling of vegetation and bee diversity was conducted in a paired sampling design, where fynbos (Natural) sub-sites were paired with sub-sites which had previously been afforested with pines (Post-Pine Recovery; PPR) and the two sub-sites were separated by a distinct, linear boundary (Natural/PPR boundary). Sampling was conducted along transects parallel to the boundary and extending in both directions from the boundary into the Natural and in the opposite direction into PPR sub-sites. Five transects were positioned at 3, 10, 20, 30, and 40 m from the boundary (Ecotone) and three were positioned at 60, 80, and 100 m from the boundary (Deep). In Chapter 2, I found that natural sub-sites consistently had higher total plant species abundance and species richness than PPR sub-sites. Approximately two thirds of plant species were more abundant in Natural sub-sites than in PPR sub-sites. There was no significant correlation in species richness or abundance with distance from the Natural/PPR boundary. Some genera are cautiously indicated as having lower success in recovery after pine afforestation: Erica spp., Restio spp., Hypodiscus spp. while Helichrysum spp. is also tentatively indicated to recover well in PPR sub-sites. Soil disturbance and concomitant disruption of normal ecosystem functions, including pollination, is indicated as a probable reason for disruption of plant recovery. In Chapter 3, sweep netting methodology was tested for the Observer Effect. A noticeable increase in bee visitation frequency to a common generalist plant species in bloom, Metalasia densa, was correlated with longer waiting periods after I stopped moving indicating the presence of an Observer Effect. This suggests that sweep netting for bees should only be commenced after a waiting period of five minutes during which the sweep netter is motionless. In Chapter 4, using a flight-intercept modified pan trap, I compared bee species richness and bee species abundance across different seasons and in both mass-flowering and sparser flower patches. There was no significant difference in bee species richness between Natural and PPR sub-sites. All bee species, except one complex, were more abundant in Natural sub-sites. Nearly two thirds of all bee species (n=37 of 56) caught with sweep netting and the modified pan trap are undescribed species. Similar to the vegetation, the effects of soil disturbance as a result of decades of pine forest shading and pine forest litterfall followed by an unusually hot pine forest fire are indicated as the most likely reasons for lower bee abundance in PPR sub-sites. This is due to the difficulty associated with viable nest establishment and suitable pollen and nectar forage availability in disturbed areas. In Chapter 5, the newly developed Pan and Flight Intercept Combination (PAFIC) trap’s design, pilot testing, and comparison with the traditional pan trap is discussed. A preliminary test suggests that the PAFIC trap is more efficient (with higher abundance) than the traditional pan trap. In Chapter 6, I discuss the implications of the disturbance of pine forestry and unusual pine fire to plant species and bee species assemblages. Bee-pollination webs in PPR sub-sites are indicated as being substantially simpler than those in Natural areas as well as compositionally different. The recovery of pollination as a keystone process in post pine-afforestation areas faces a substantial challenge given the disturbance to soil that decades of pine afforestation followed by pine forest fire can cause. Some suggestions are made for the restoration of fynbos areas recovering from pine afforestation including a discussion of augmenting re-vegetation measures (fynbos seed dispersal and seedling planting) with methods of restoring of healthy pedogenesis, epigaeic arthropod communities, and fynbos seedbanks. / AFRIKAANSE OPSOMMING: Die huidige globale biodiversiteit krisis is gekenmerk meestal deur die verlies van spesies as gevolg van die vernietiging van habitat. Maar daar is ook ander groot bedreigings – veral merkbaar indringerspesies. Die term “biodiversiteit brandpunt” is geskep om gebiede vir bewaring prioritisering te beklemtoon - gebiede wat 'n hoë biodiversiteit bevat wat bedreig word deur die vernietiging van habitat, indringerspesies, ens. Die Kaap Floristiese Streek (KFS) in die Wes-Kaap (WK) Provinsie van Suid-Afrika het die hoogste biodiversiteit van alle Mediterreense tipe klimaat streke wêreldwyd, en is onder die globale biodiversiteit brandpunte geklassifiseer. Die KFS, 'n Mediterreense-tipe klimaat heideveld met 'n natuurlike hoë brand frekwensie, word bedreig as gevolg van transformasie deur ontwikkeling, versteurde (verhoogde) vuur regimes, en indringer organismes, veral indringerbome. Sulke bedreigings versteur hoeksteen spesies en die hoeksteen prosesse, insluitende insek bestuiwer samestelling en verwante insek blom besoekings webbe en frekwensies. Indringer dennebome (Pinus spp.) is 'n ernstige bedreiging vir insek blom besoeking want dennebome verskaf skaduwee aan baie inheemse plantegroei in die KFS. Min is bekend oor die langtermyn effekte op insek blom besoekers en plantegroei restorasie na denneboom verwydering en restorasie gebiede na sodanige bome verwyder word. Ek ondersoek die restorasie van plantegroei en die belangrikste insek bestuiwer, bye, na die vernietiging van dennebome deur vuur en passiewe herstel in 'n KFS vallei in die Wes-Kaap. In 1999 het'n veldbrand baie van die WK Limietberg Natuurreservaat saam met 'n aangrensende denneboom bosbouplantasie gebrand - wat toe gelaat is om te herstel via intermediêre suksessie na inheemse fynbos plantegroei. Dit bied 'n ideale geleentheid om die blywende gevolge van denneboom aanplanting in die KFS te ondersoek. In twee data hoofstukke, vergelyk ek die passiewe herstel van plantegroei na ‘n brand (Hoofstuk 2) en by diversiteit (Hoofstuk 4) in gebiede wat voorheen geplant is met dennebome teenoor diegene wat natuurlike fynbos vervat het. Om te verbeter op steekproefmetodiek, het ek 'n eksperiment onderneem wat demonstreer hoe die Waarnemer Effek by monsterneming met 'n vee-net beïnvloed (Hoofstuk 3), en het ek 'n nuwe monsterneming toestel ontwerp (Hoofstuk 5) vir insek blom besoekers. Monsterneming van plantegroei en by diversiteit is uitgevoer in 'n gegroepeerde steekproef ontwerp, waar fynbos (Natuurlik) sub-terreine gegroepeer is met sub-terreine wat voorheen aangeplant was met dennebome (Na Denneboom Verwydering Herstel; NDVH) en die twee sub-terreine is geskei deur 'n duidelike, lineêre grens (Natuurlik / NDVH grens). Steekproefneming is gedoen langs transekte parallel tot die grens en versprei in albei rigtings van die grens tot binne die natuurlike fynbos en in die teenoorgestelde rigting tot binne NDVH sub-terreine. Vyf transekte is geposisioneer binne 50 m van die grens (Oorgang sone) en drie is ver geplaas van die grens (Diep). In Hoofstuk 2 het ek gevind dat natuurlike sub-terreine konsekwent hoër totale getal plant individue en spesierykheid as NDVH sub-terreine gehad het. Ongeveer twee derdes van plantspesies was meer volop in natuurlike sub-terreine as in NDVH sub-terreine. Daar was geen beduidende korrelasie in spesierykheid of totale hoeveelheid plant individue met betrekking tot afstand van die Natuurlike /NDVH grens. Sommige genera word versigtig aangedui as met laer sukses in die restorasie terreine na denneboom aanplanting: Erica spp., Restio spp., Hypodiscus spp. terwyl Helichrysum spp. voorlopig aangedui is as goed herstel in NDVH sub-terreine. Grondversteuring en gepaardgaande ontwrigting van normale funksionering van die ekosisteem, insluitend bestuiwing, word aangedui as 'n waarskynlike rede vir die ontwrigting van die herstel van plantegroei. In Hoofstuk 3 is vee-net metodologie getoets vir die Waarnemer Effek. 'N merkbare toename in by besoeking frekwensie van 'n algemene plantspesie in blomtyd, Metalasia densa, is gekorreleer met langer wagtydperke nadat ek gestop het om te beweeg, en dui dus op die teenwoordigheid van 'n Waarnemer Effek. Dit dui daarop dat die vee-net vir bye eers gebruik moet word na 'n wagtydperk waartydens die waarnemer bewegingloos verkeer. In Hoofstuk 4, met behulp van 'n vlug-onderskep gewysigde pan lokval, het ek by spesierykheid en totale by hoeveelheid vergelyk oor verskillende seisoene en in beide massa-beblomde en yler blom kolle. Daar was geen beduidende verskil in by spesierykheid tussen natuurlike en NDVH sub-terreine. Alle by spesies, behalwe een spesie kompleks, was meer volop in natuurlike sub-terreine. Byna twee derdes van alle by spesies (n = 37 van 56) gevang met vee-nette en die van die gewysigde pan lokvalle is onbeskryfde spesies. Soortgelyk aan die plantegroei, is die gevolge van grondversteuring as gevolg van dekades van denneboom bos skadu en denneboom bos blaar afval gevolg deur 'n buitengewoon warm denneboom bos brand as die mees waarskynlike redes vir laer by hoeveelheid in NDVH sub-terreine aangedui. Dit is as gevolg van die probleme wat verband hou met lewensvatbare nes vestiging en geskikte stuifmeel en nektar voer beskikbaarheid in versteurde gebiede. In Hoofstuk 5 is die nuut ontwikkelde Pan en Vlug Onderskep Kombinasie (PEVOK) lokval ontwerp, aanvanklike toetsing, en vergelyking met die tradisionele pan lokval bespreek. 'N Voorlopige toets dui daarop dat die PEVOK lokval meer doeltreffend (met 'n hoër oorvloed) is as die tradisionele pan lokval. In Hoofstuk 6 bespreek ek die implikasies van die versteuring van denneboom bosbou en ongewone denneboom vuur met betrekking tot plant spesies en by spesies samestelling. By-bestuiwing webbe in NDVH sub-terreine word aangedui as wesenlik eenvoudiger as dié in natuurlike areas asook verskillend in samestelling. Die herstel van bestuiwing as 'n hoeksteen in na denneboom-aangeplante gebiede staar 'n aansienlike uitdaging in die gesig, gegee die versteuring van grond wat dekades van denneboom aanplanting gevolg deur denneboom bos brand kan veroorsaak. Sommige voorstelle is gemaak vir die herstel van fynbos gebiede wat herstel van denneboom aanplanting, insluitend 'n bespreking van die aanvulling van plantegroei hervestiging maatreëls (fynbos saadverspreiding en saailinge plant) met die metodes van die herstel van 'n gesonde pedogenese, bogrondse geleedpotige gemeenskappe, en fynbos saadbanke.

As flower visitors, ants rarely benefit a plant, commonly disrupting pollination by deterring other flower visitors, or stealing nectar. This thesis examines three aspects of ant-flower interactions, focusing on the occurrence of floral traits that prevent disruption of pollination and a novel means by which ants may influence pollinator behaviour. To assess which types of plant species possess ant-repelling floral traits I carried out a survey of 49 Neotropical plant species. Around a third of these species were repellent to the common generalist ant Camponotus novograndensis (Formicinae). This repellence was positively correlated with large nectar volumes within individual flowers. It appears that there has been selection for floral ant-repellence as a defence against ant thieves in plant species that invest in large volumes of nectar. In some cases these repellent traits were effective against a wide range of ant species. However, in no plant species were predacious ants particularly repelled, indicating that there may be little selective pressure on non-ant-plants to defend potential pollinators from aggressive ants. To investigate the importance of coevolution in determining the effectiveness of ant-repellents, a small but diverse range of Mediterranean plant species were tested with the invasive nectar thieving ant Linepithema humile (Dolichoderinae) and the native but non-nectar thieving ant Messor bouvieri (Myrmecinae). Responses of both ant species to floral traits were very similar. The ability of some plants to restrict access to ant species with which they have no evolutionary history may help to reduce the impact invasive species, as nectar thieves, have on plant-pollinator interactions. It is reported that flowers recently visited by bees and hoverflies may be rejected for a period of time by subsequent bee visitors through the detection of scent-marks. Nectar-thieving ants could potentially influence the foraging decisions of bees in a similar way if they come to associate ant trail pheromones or footprint hydrocarbons with poor reward levels. However, my empirical work found no differences were found in bee visitation behaviour between flowers of Digitalis pupurea (Plantaginaceae), Bupleurum fruticosum (Apiaceae) or Brassica juncea (Brassicaceae) that had been in contact with ants and control flowers. Ant-attendance at flowers of these species may not reduce reward levels sufficiently to make it worthwhile for bees to incorporate ant scent-marks into foraging decisions. Investigations like these into the interactions between ants, flowers and other flower visitors are essential if we hope to understand the part ants play in pollination ecology, and determine how ants have helped shape floral evolution.

Land-use history has been recognized as an important factor in shaping biological communities in clear-cuts. Many solitary bees and flower beetles (Cerambycidae: Lepturinae) are commonly found in clear-cuts, which serve as early successional habitats. I analyzed the effect of land-use history on the abundance and species richness, as well as the preference for land-use history in specific species, of solitary bees and flower beetles in coniferous clear-cuts in southern Sweden. Additionally, the effect of site-specific environmental factors was examined. Insects were caught with blue, white and yellow pan-traps in 48 clear-cuts, of which half were meadow and half were forest in the 1870s. With few exceptions, the species found did not show preference for any land-use history. Furthermore, land-use history had no significant effect on the abundance or species richness of solitary bees or flower beetles. This may be due to pan-traps being less attractive in flower-rich locations, a bias in the sampling method. However, species richness and abundance of solitary bees was higher in young clear-cuts (2-4 years old), probably best explained by more exposed soil and higher frequencies of flowering plants in newer clear-cuts. Abundance of flower beetles was higher in old clear-cuts (6-8 years old). This may be due to larger amounts of more strongly decomposed wood in older clear-cuts, which is used in the flower beetles´ larval development. I conclude that solitary bees are likely to benefit if clear-cuts, particularly with meadow history, are kept more open by introducing disturbance regimes, as suggested by previous studies.

The potential harm caused to bees and other pollinators by the widespread use of neonicotinoids has the capacity to pose a real and immediate threat to both the environment and humans. The benefits that bees and other pollinators provide, combined with the potential of harm they may face, are important enough to warrant a more comprehensive testing apparatus by which to evaluate threats to their population. Environmentally, bees and other pollinators are an important piece of ecosystemic balance--from pest management to pollination of plants that are a part of many species' diet. Anthropologically speaking, the way of life humans have been accustomed to and even need in order to survive is also largely dependent on a healthy population of bees and other pollinators; up to 70% of plants and vegetables we eat are directly a result of pollinators, and one third of every mouthful humans consume is attributed to pollinators. Without a healthy population of pollinators, the agricultural variety and nutritional availability would drastically decrease. Moreover, these agricultural products pollinators are responsible for also affect billions of dollars on both a national and global level. In many ways, the economic stability of the United States is at an equal risk as the pollinators. For example, an inability to produce many of our own agricultural staples would leave local and regional livelihoods disrupted and change the United States' import/export position. Moreover, this is not just a national problem. Pollinators are responsible for over 150 billion dollars globally in agriculture. Many of the nutrients humans need to be healthy would be in short supply. While scientists continue to study the possible effects of neonicotinoids on pollinators, how should policy makers respond? In this thesis, I argue that the various and drastic ways in which pollinators impact our environment and every day life, combined with the potential of the harsh threats their collapse would entail, warrant a more stringent approach to the evaluation of potential harms like neonicotinoids. An ethical risk assessment, as I define one, would be an appropriate tool to apply to this situation to guide policy makers in drafting regulations even in the absence of scientific certainty. Ethical risk assessments are a tool by which to evaluate the moral and ethical responsibilities in a whole host of different scenarios, one of which is neonics and pollinators. In other words, this ethical risk assessment will be used as an instrument by which to determine whether or not there is a sufficient risk to the population of pollinators, thus determining whether regulation is appropriate. Through application of this risk assessment, I will show that in this particular case regulation is appropriate due to the risks neonics pose to pollinators in light of the evidence that we do have. I develop a set of criteria for an ethical risk assessment. The criteria are a result of a combination of existing literature and some novel connections I draw here. This list, I argue, is what constitutes an ethical risk assessment. Ethical risk assessment, grounded in Utility Theory, is appropriate here because of its calculative apparatus and sociopolitical applicability.

There is growing awareness about the value of preserving and restoring floral-rich habitats for the benefit of pollinators, especially native bees. The increasing demand for native plants in pollinator habitat restoration and other ecological landscaping applications, combined with the desire for more robust and predictable plant habits, have led to the selection and breeding of native cultivars. Yet, little is known about how these cultivated varieties differ from the native species in their ability to attract and support pollinators. I compared flower visitation by all insect pollinators to 12 native herbaceous plant species and 14 native cultivars in a replicated field experiment at two sites over two years. I classified insect pollinators during visual field observations into seven taxonomic and functional groups. I found seven native species to be visited significantly more frequently by all insect pollinators (combined) than their cultivars, four were visited equally, and one native cultivar was visited more frequently than the native species. Bees (both native and non-native) and moths/butterflies exhibited similar preferences, whereas flies showed no preference between the native species and the native cultivar. Our study shows that many insect pollinators prefer to forage on native species over cultivated varieties of the native species, but not always, and not exclusively. Some native cultivars may be comparable substitions for native species in pollinator habitat restoration projects, but all cultivars should be evaluated on an individual basis. Plant selection is integral to the value and success of pollinator habitat restorations, yet there is little consistency and overlap in pollinator planting recommendations and very little empirical data to support plant choice. Non peer-reviewed pollinator plant lists are widely available and are often region-specific, but they are typically based on anecdotal rather than empirical data and lack in specificity. To help close the gap between anecdotal and empirical data, and between practice and research, I reviewed the published literature on plant selection for pollinator habitat restoration. I explicitly reviewed and compared the value of native plant species, near-natives, non-natives and native cultivars. From there, I identified gaps in the literature that are most needed in practice and recommended basic strategies for practitioners to navigate plant lists and choose the best plants for a site's success.

Pollinator biodiversity and abundance is an ecosystem service vital for humans, provisioning a range of essential goods including food, fibre and medicines. Despite this, pollinators are under threat and are experiencing global declines. Habitat loss is a driving force behind such declines and, as such, the potential to provision more pollinator habitat is of interest. Currently, urban areas host abundant unused space in the forms of roofs and walls, which could be utilized to provision some pollinators with additional forage, and possibly nesting sites, without compromising human use of the land. While several studies exist regarding the habitat potential of living roofs, the impact of living walls on biodiversity is little studied. This paper sets out a theoretical approach on whether living walls could be used to host pollinator habitat by surveying living wall manufacturers regarding the physical properties of the living wall systems they use and their plant choice.

This Master thesis is focused on selected pollinators of our meadows and their didactic integration into education. The thesis is divided into two parts - theoretical and practical. In theoretical part, there are defined two orders (Hymenoptera and Diptera), process of pollination, plants pollination strategies and pollen grain. Practical part is focused on research of dipterans (particularly on hoverflies) of which purpose was to find out which plants are most pollinated. Subsequent section deals with analysis of secondary school Biology textbooks in terms of representation of selected pollinators. Next section contains plan of practical exercise, which deals with whether honey contains pollen grains. In final section of practical part, a worksheet is presented, which verifies pupil's knowledge about pollinators. KEYWORDS Hymenoptera, Diptera, hoverfly research, pollinators, pollen, textbook analysis