It is increasingly recognized that a sustainable future for agriculture must build on ecosystem services. Pollination is an important ecosystem service in all agroecosystems. In much of Africa the main challenge is conserving pollinator biodiversity in traditionally “ecologically-intensive” agroecosystems that are changing to meet different demands for food security and poverty alleviation, rather than safeguarding pollination in transition from conventional agricultural systems, with a high reliance on purchased inputs, to “ecologically-intensive” agroecosystems using natural inputs provided by biodiversity. Priority issues for research and development in pollination services in Africa include, inter alia: quantification and documentation of pollination deficits and finding measures to address these; socio-economic valuation of pollinator-friendly practices; assessment of lethal and sub-lethal effects of farming methods, such as pesticide use, on crop pollinators; identification of habitat management practices that enhance synergies between pollinator lifecycles and crop growing patterns; and policy analysis in relation to drivers and trends in pollination services and management.

International audience | Unprecedented growth in human populations has required the intensification of agriculture to enhance crop productivity, but this was achieved at a major cost to biodiversity. There is abundant local-scale evidence that both pollinator diversity and pollination services decrease with increasing agricultural intensification. This raises concerns regarding food security, as two-thirds of the world’s major food crops are pollinator-dependent. Whether such local findings scale up and affect crop production over larger scales is still being debated. Here, we analyzed a country-wide dataset of the 54 major crops in France produced over the past two decades and found that benefits of agricultural intensification decrease with increasing pollinator dependence, to the extent that intensification failed to increase the yield of pollinator-dependent crops and decreased the stability of their yield over time. This indicates that benefits from agricultural intensification may be offset by reductions in pollination services, and supports the need for an ecological intensification of agriculture through optimization of ecosystem services.

Understanding the inter-play plant–pollinator is essential to develop ecosystem services of faba bean and improved populations for low-input systems. We analyzed the phenotypic selection exerted by pollinators on floral traits involved in the plant pollinator inter-play. We test whether variation in pollinator-related floral traits is associated with differences among plants in seed production patterns. We used open pollination and pollinator-exclusion environments to examine pollinator mediated selection and selection for autonomous selfing in six gene-pools of Vicia faba over three consecutive years. We recorded, by using Digital Image Analysis, functional floral traits related to attraction, sexual dimension, and vector matching/pollen transfer efficiency. Nine production components were measured to categorize seed production patterns. Our approach used a series of Multivariate Regression Analyses (MRA) to explore which floral traits provided the best models to explain seed production patterns in each gene-pool and pollination environment. MRA showed that variation in the incidence of pollinator-mediated selection on floral traits or in the selection for autonomous selfing can substantially contribute to differences in seed patterns. The underlying floral mechanisms are specific to the gene-pool and largely unrelated among gene-pools. Consistent results among gene-pools involved no evidence of pollinator-mediated selection as result of the floral traits under study on the main predictors of crop yield, pods and seeds per plant. However, relevant predictors of crop yield such as pod length and seed dimensions and weight were pollinator-dependent because of pollinator-mediated selection on sexual dimension, floral display and vector matching traits. We caution against dismissing pollinator-mediated selection as driver of seed production patterns variation which may be influenced by the gene-pool and by the gene-pool × pollination environment interaction. | We gratefully acknowledge the EU-FP7- KBBE-2009-3 project SOLIBAM (Strategies for Organic and Low-input Integrated Breeding and Management) for financial support. | Peer Reviewed

Tropical countries contribute substantially to global agricultural production, but the majority of farmers are small-scale subsistence farmers. Their comparably low agricultural productivity is coupled with major yield gaps. Agricultural expansion and the intensive use of agro-chemicals are the major cause for the destruction of tropical habitats and biodiversity loss and pose a threat to ecosystem services. However, many tropical small-holder farmers rely on ecosystem services like insect pollination or natural pest control, which may play an indispensable role in closing yield gaps. In addition, losses from pollination deficits or pest pressure are usually mitigated by the use of managed pollinators or pesticides that in turn can be harmful to ecosystem services provided by wild insects. We aim to shed light on the relative importance of pollination services, common management practices and their interaction. We evaluated the benefits from pollination services for cucumber (Cucumis sativus) production and how wild bees (the main cucumber pollinators in the region) are influenced by management on four different spatial scales. We furthermore assessed income loss due to dis-services from seed predating ants in order to suggest management measures that may reduce yield gaps. Our work comprises experimental field studies on small-scale vegetable production in homegardens in tropical central Sulawesi, Indonesia and a review on pollination services to highlight existing information and to close information gaps on pollinations services for crops. In the first study (chapter 2) we tested how different management practices (insect pollination, weed control, fertilization and herbivore control) affect cucumber fruit set and yield and how these variables influence each other. We found that insect pollination, fertilization and weed control increased crop fruit set and yield in an additive way. However, fertilization and weed control alone could not compensate for pollination loss, which was the most important driver and accounted for 75 % of the yield. We found an interaction between the weed control and pollination treatment in which weed control strongly influenced insect-pollinated plants but not wind and self-pollinated plants. This indicates that weed control contributes to closing yield gaps, but only in addition to insect pollination. In contrast, insecticides to control herbivores did not influence yield. We recommend shifting the focus from common management practices towards more sustainable management to enhance pollination services and stress the importance for policy driven regulations of reduced and better targeted pesticide application in tropical agroecosystems. In the second study (chapter 3), we evaluated variables from three spatial scales to better understand bee communities indispensable for cucumber production. We further assessed if the response to these scale predictors depends on pollinator body size and sociality. Yield increased significantly with increasing number of flower-visiting bee individuals (mainly composed of wild solitary bees which translates into a net income decline of 47% if half of the bees would be lost. For optimized bee management, farmers need to consider four spatial scales. On the garden scale (1), the homegarden-wide percentage of flower cover predicted pollinator attraction best, if, on the adjacent-habitat scale (2), a higher percentage of homegardens (at least 20%, best 50% in a 200m radius) surrounded the study garden. In addition, the landscape scale (3), distance to the rainforest (up to 2.2 km) had also a significant effect on total bee flower visitor. This effect was dominated by small bees which increased closer to the forest. We conclude that farmers need to adjust bee management accordingly to reduce major yield gaps. High percentages of crops and non-crop plants flowering inside the homegarden can attract pollinators from adjacent source habitats that are mainly homegardens as well. In the third study (chapter 4), we aimed to assess the effect of seed predation by ants on sown seeds of four crop species (C. sativus, Daucus carota, Capsicum frutescens and Solanum melongena) and the resulting impact on the net income of small-scale farmers. Furthermore, we tested if ant seed predation differs with or without insecticide and herbicide applications. We found that ant seed predation was high for all crops (42.0 %, 49.4 %, 48.0 % and 50.6 % for C. sativus, D. carota, C. frutescens and S. melongena, respectively), potentially reducing farmers’ net income by half. Application of insecticides and herbicides did not influence ant seed predation or total ant abundance, but influenced ant species-specific abundances positively or negatively. Despite ant species-specific responses to insecticide and herbicide applications, we found consistently high seed predation rates across all gardens. We conclude that high seed predation is caused by high overall ant abundance mediated through functional redundancy of ant species. We recommend more environmentally friendly and sustainable practices such as overseeding or seedling production in nurseries to reduce chemical pest control. In the fourth study (chapter 5), we reviewed pollination services and their importance to crops focusing on another understudied geographical region - the Neotropics - to get an overview of the main pollinator taxa and the dependence on pollination services of crops. In addition, we summarized pollination research methodologies and discuss pollination relevant farm and landscape management, as well as socio-economic drivers affecting pollination services. We have shown that pollination services by wild pollinators are important for crop production. However, knowledge gaps exist in terms of the quantity, quality and stability of crop production provided by animal pollinators. It is also critical to understand how multiple socioeconomic drivers influence the selection of particular management systems and, thus, the environmental services delivered. In conclusion, pollination services are of major importance for closing yield gaps in tropical small-scale agriculture, such as homegardens. Although common management practices such as the use of agro-chemicals influence yield, they do not compensate yield gaps due to pollinator loss or ant seed predation. The enhancement of pollination services should be considered as well as the reduction of pesticide use in the majority of tropical agroecosystems. Farmers should adapt environmentally friendly and more sustainable practices adjusted to bee management considering four spatial scales to reduce major yield gaps.

1. Pollinating insects provide crucial and economically important ecosystem services to crops and wild plants, but pollinators, particularly bees, are globally declining as a result of various driving factors, including the prevalent use of pesticides for crop protection. Sublethal pesticide exposure negatively impacts numerous pollinator lifehistory traits, but its influence on reproductive success remains largely unknown. Such information is pivotal, however, to our understanding of the long-term effects on population dynamics. 2 We investigated the influence of field-realistic trace residues of the routinely used neonicotinoid insecticides thiamethoxam and clothianidin in nectar substitutes on the entire life-time fitness performance of the red mason bee Osmia bicornis. 3 We show that chronic, dietary neonicotinoid exposure has severe detrimental effects on solitary bee reproductive output. Neonicotinoids did not affect adult bee mortality; however, monitoring of fully controlled experimental populations revealed that sublethal exposure resulted in almost 50% reduced total offspring production and a significantly male-biased offspring sex ratio. 4 Our data add to the accumulating evidence indicating that sublethal neonicotinoid effects on non-Apis pollinators are expressed most strongly in a rather complex, fitness-related context. Consequently, to fully mitigate long-term impacts on pollinator population dynamics, present pesticide risk assessments need to be expanded to include whole life-cycle fitness estimates, as demonstrated in the present study using O. bicornis as a model.

Pollination is an important ecosystem service that benefits human welfare by increasing the quantity and quality of fruit and seed set of many crops. The decline in bee abundance and diversity in recent years may result in a decrease in pollination services, which could have a major impact on world food supplies. In Norway, there is a lack of studies on pollination in a farming context. Here I present a field study on the pollination service in apple orchards in Lofthus, Western Norway. I studied the distribution of managed and wild bees, factors that affect their presence, and how this affects the apple yield. The field methods used were transect walks at the farms, observations at branches, pan traps and transect in various habitat types. Transect walks at farms and observations at branches and pan traps were used for statitstical analyses, while transect walks in various habitat types were combined and used to create a species distribution model (SDM). There was a high abundance of honeybees in the apple orchards; among the wild pollinators bumblebees were more common. Honeybees were more abundant in sunny weather, while bumblebees were not as strongly affected by weather. Bumblebee abundance increased towards higher elevations on the farms in the transect walk data, while SDM showed increasing elevations (up to 240 meter) to have a positive effect on predicted presence of both honeybee and bumblebees. Distance to forest did not affect the bumblebees, but SDM showed that all of the pollinators preferred the upper, less disturbed parts of the farm areas which were closer to natural habitats. I also showed that pollinator diversity had a positive impact on the fruit set and yield. These results indicate that both honeybee and bumblebee abundance have a positive impact on the fruit set and yield of apples in Lofthus. They also indicate that to enhance the wild pollinator abundance, undisturbed, flower rich habitat is important. | Master i Biologi | MAMN-BIO | BIO399

Thesis (PhD)--Stellenbosch University, 2014. | ENGLISH ABSTRACT: Insect pollination contributes in various degrees toward the production of a variety of agricultural crops that ensure diversity and nutritional value in the human diet. Although managed honeybees (Apis mellifera L.) are still the most economically valuable pollinators of monoculture crops cultivated globally, wild pollinator communities can contribute substantially toward crop pollination through pollination ecosystem services sourced from neighbouring natural habitats. Pollination ecosystem services are thus valuable and can motivate for the protection of natural ecosystems hosting diverse insect pollinator communities. F1 onion hybrid seed production is entirely dependent on high insect pollinator activity to ensure cross pollination, seed set and profitable seed yields. Data was collected on 18 onion hybrid seed crops grown in the semi‐arid Klein Karoo and southern Karoo regions of the Western Cape, South Africa. These two main production regions are located within the Succulent Karoo biome, recognized as a global biodiversity hotspot of especially high plant diversity. It is also habitat to the indigenous Cape honeybee (Apis mellifera capensis Esch.). Sites selected varied in the percentages of available natural habitat and managed honeybee hives stocking density. Diverse anthophile assemblages were sampled with pan traps within all the onion fields, regardless of the percentage of available natural habitat near the crop. Crop management practices significantly affected the diversity of anthophile species caught within onion fields, although less than 20% of this diversity was observed actually visiting onion flowers. The honeybee (managed and wild) was by far the most important pollinator because of its high visitation frequency and regular substantial onion pollen loads carried on their bodies. Honeybee visitation significantly increased onion hybrid seed yield, while anthophile diversity and non‐Apis visitation had no effect on seed yield. Neither managed hive density, nor percentage natural habitat were important in determining honeybee visitation or seed yield. Total annual rainfall was the only significant factor determining honeybee visitation. Secondary factors caused by rainfall variability, such as wild flower abundance or soil moisture, may have significantly affected honeybee visitation. In addition, the positive correlation between honeybee visitation and the diversity of hand‐sampled insects from onion flowers; indicate that either or both onion varietal attractiveness and/or pollinator population size may have had significant effects on overall insect visitation. Honeybees showed marked discrimination between hybrid onion parental lines and preferred to forage on one or the other during single foraging trips. Hybrid onion parents differed significantly in nectar characteristics and onion flower scent which would encourage selective foraging through floral constancy. Interspecies interactions were insignificant in causing increased honeybee pollination because of the scarcity of non‐Apis visitors. Most farming practices are subjected to favourable environmental conditions for successful production. However, and especially in the South African context, the dependence of onion hybrid seed crops on insect pollination for successful yields, increase its reliance on natural ecosystem dynamics that may deliver abundant wild honeybee pollinators, or attract them away from the crops. Nevertheless, this dependence can be mitigated effectively by the use of managed honeybee colonies to supplement wild honeybee workers on the flowers. | AFRIKAANSE OPSOMMING: Insek bestuiwing dra in verskillende grade by tot die produksie van landbou gewasse wat variteit en voedingswaarde in die mens se dieet verseker. Al is die heuningby (Apis mellifera L.) steeds die waardevolste ekonomiese bestuiwer van verboude enkelgewasse, kan wilde bestuiwers wesenlik bydra tot gewasbestuiwing deur middel van ekosisteem dienste afkomstig van natuurlike habitatte. Bestuiwing ekosisteem dienste is daarom waardevol en kan dus die bewaring van natuurlike ekosisteme, wat diverse gemeenskappe huisves, regverdig. F1 basterui saadproduksie is totaal afhanklik van hoë insek‐bestuiwer aktiwiteit om kruisbestuiwing, saadvorming en winsgewende saadopbrengste te verseker. Data is ingesamel op 18 basterui saad aanplantings in die half‐droë Klein Karoo en suid‐Karoo streke van die Weskaap, Suid‐Afrika. Hierdie twee hoof produksie streke is geleë binne die Sukkulente Karoo bioom wat erken word as ʼn globale biodiversiteits “hotspot” met hoë plant diversiteit. Dit is ook die habitat van die inheemse Kaapse heuningby (Apis mellifera capensis Esch.). Aanplantings is gekies om verskillende grade van beskikbare natuurlike habitat en bestuurde heuningby korf digthede te verteenwoordig. Diverse versamelings blom‐besoekers is versamel met water‐wippe in al die aanplantings, ongeag die persentasie natuurlike habitat beskikbaar by elke aanplanting. Gewas bestuurspraktyke het die diversiteit van blombesoekers betekenisvol beïnvloed. Tog is minder as 20% van hierdie diversiteit as aktiewe besoekers op die uiekoppe waargeneem. Heuningbye (bestuur of wild) was oorwegend die belangrikste bestuiwers as gevolg van hoë besoek frekwensies en wesenlike ladings uiestuifmeel op hulle liggame. Heuningby besoeke het saadopbrengs betekenisvol verhoog, maar blom‐besoeker diversiteit en nie‐Apis besoeke het geen effek op saadopbrengs gehad nie. Bestuurde korf digtheid en persentasie natuurlike habitat was nie belangrik in die bepaling van heuningby besoeke of basterui saadopbrengste nie. Totale jaarlikse reënval was die enigste betekenisvolle faktor wat heuningby besoeke bepaal het. Sekondêre faktore wat versoorsaak word deur reënval veranderlikheid, soos veldblom volopheid of grondvog, kon betekenisvolle effekte op die aantal heuningby besoeke gehad het. Bykomend, dui die positiewe korrelasie tussen heuningby besoeke en die diversiteit van hand‐versamelde insekte vanaf die uiekoppe op die moontlike betekenisvolle effek van elk of beide basterui variteit aantreklikheid en/of bestuiwer populasie grote op algehele insek besoeke. Heuningbye het noemenswaardige diskriminasie getoon tussen die basterui ouerlyne en het verkies om op een of die ander te wei tydens enkele weidingstogte. Basterui ouerlyne het betekenisvol verskil in nektar eienskappe en blomgeur wat die selektiewe weiding van heuningbye, toegepas deur blomkonstantheid, sal aanmoedig. Tussen‐spesie interaksies was onbetekenisvol in die verhoging van heuningby bestuiwing omdat nie‐Apis besoekers baie skaars was. Meeste boerdery praktyke is onderhewig aan gunstige omgewings toestande vir suksesvolle produksie. Maar, en veral in die Suid‐Afrikaanse konteks, omdat basterui saad aanplantings afhanklik is van insek bestuiwing vir suksesvolle opbrengste, word daar meer staat gemaak op natuurlike ekosisteem dinamika wat volop wilde heuningby bestuiwers kan voorsien, of selfs bestuiwers van die aanplanting kan weg lok. Nietemin, hierdie afhanklikheid kan effektief verlaag word deur die gebruik van bestuurde heuningby kolonies om die aantal wilde heuningby werkers op die blomme aan te vul. | Doctoral

Assessment of the impact of transgenic crops on non-target organisms (NTO) is a prerequisite to their release into the target environment for commercial use. Transgenic sweetpotato varieties expressing Cry proteins (Bt sweetpotato) are under development to provide effective protection against sweetpotato weevils (Coleoptera) which cause severe economic losses in sub-Saharan Africa. Like any other pest control technologies, genetically engineered crops expressing insecticidal proteins need to be evaluated to assess potential negative effects on non-target organisms that provide important services to the ecosystem. Beneficial arthropods in sweetpotato production systems can include pollinators, decomposers, and predators and parasitoids of the target insect pest(s). Non-target arthropod species commonly found in sweetpotato fields that are related taxonomically to the target pests were identified through expert consultation and literature review in Uganda where Bt sweetpotato is expected to be initially evaluated. Results indicate the presence of few relevant non-target Coleopterans that could be affected by Coleopteran Bt sweetpotato varieties: ground, rove and ladybird beetles. These insects are important predators in sweetpotato fields. Additionally, honeybee (hymenoptera) is the main pollinator of sweetpotato and used for honey production. Numerous studies have shown that honeybees are unaffected by the Cry proteins currently deployed which are homologous to those of the weevil-resistant Bt sweetpotato. However, because of their feeding behaviour, Bt sweetpotato represents an extremely low hazard due to negligible exposure. Hence, we conclude that there is good evidence from literature and expert opinion that relevant NTOs in sweetpotato fields are unlikely to be affected by the introduction of Bt sweetpotato in Uganda.

The order Lepidoptera is an ecologically important insect group which undertake a range of ecosystem services, including herbivory, decomposition, and most notably pollination. Numerous studies on Lepidoptera abundance and diversity in the Northern Hemisphere have revealed large, sustained declines in population numbers and alterations to range size over an alarmingly high proportion of species for several decades. The overwhelming trend is one of ongoing net loss of biodiversity at a global scale. Land-use changes resulting in a lack of nectar sources, a loss of critical host plants, and the interaction of these impacts with the increasing pressures wrought by climate change on already vulnerable taxa are thought to be the main drivers behind the temporal patterns of decline being seen. New Zealand’s Lepidoptera fauna is globally significant for its unique assemblage of endemic moths and butterflies. Despite this, population trends of New Zealand’s moths and butterflies are so far largely undocumented, as the long-term monitoring regimes responsible for recording declines in other countries is lacking in New Zealand. To begin to fill this gap in knowledge, databasing methods are being undertaken on 44 years’ worth of expert Lepidopterist Brian Patrick’s personal records, in order to achieve a workable dataset conducive to statistical analysis and ongoing use. Preliminary results of observations spanning 10 years indicate declines in Lepidoptera at lower elevation sites and in agricultural areas. This has significant implications for the future of conservation for our native pollinator species. Refinement of the database is needed, and ongoing exploration of the dataset with the addition of earlier observations will be valuable for strengthening trends. It is hoped that these results will inform the conservation of a key order of New Zealand’s biota and serve as a case study for the value of curiosity driven, unfunded data-collection in achieving much-needed long-term datasets.