Bees provide vital ecosystem services for cropping systems as well as natural landscapes. Declines in both both native bee and managed honey bee (Apis mellifera L.) populations has brought attention to the significance of their role as pollinators in managed and native ecosystems. As a result, conservation efforts have been undertaken to preserve them. While considerable attention has been given to honey bees, relatively little is known about many native bee species. Of particular interest is the family Halictidae, which can comprise the majority of observed individuals in many habitats. These, often small, bees are difficult to identify, and, as a result, relatively little is known about their preferred floral hosts. Because bee species assemblages vary significantly from region to region, it is important to have an understanding of local populations and their floral hosts. It is also important to understand factors which affect the quantity and quality of floral resources, such as anthropogenic disturbance. The Pacific Northwest is a diverse landscape, with rich agricultural and wildland environments that require pollinators in order to continue to thrive. Two studies examine the interface between these two systems, the first explores how roadside disturbance, which is prevalent across the world, impacts native pollinators across habitat types, and the second explores the diet of common native species, and how that diet changes across habitat types. In these studies, it was found that roadside disturbance was associated with reduced native bee diversity and abundance in the seasonally wet Willamette Valley of Oregon, but not in the more xeric Central Oregon. Bee abundance was positively correlated with temperature. Bee diet was more diverse in areas of scarce floral resources. In both regions, exotic plants were important floral hosts, representing nearly half of observed floral visitations. This thesis presents results of species analysis, floral richness and density correlations, and comparisons of floral resources used by different bee species. Implications and recommendations for land management are discussed. / Graduation date: 2013

In this project I studied the importance of pollinators in the reproduction of Gastrodia ‘long column’ and the preferences of New Zealand’s native and exotic insect pollinators. This was done in order to determine the specialisation of insect pollination in urban Christchurch. This knowledge can contribute to crop pollination, conservation efforts, and an understanding of the main drivers of the common floral traits (small, white flowers) in New Zealand. The strength of the relationship between the common traits of the New Zealand flora and the preferences of the native invertebrate fauna is not known. Traditionally it had been thought that New Zealand’s insects lack strong preferences, however recent work has not supported this. Changing landscapes worldwide have led to declines in pollinator numbers. Additionally, in New Zealand Apis mellifera numbers have declined as a result of the arrival of the varroa mite and it is important that alternative pollinating species for wild and agricultural pollination are identified. To address these needs I examined the abundance and preferences of insect pollinators in modified landscapes in and around Christchurch testing: the reliance upon pollinators by the undescribed native orchid Gastrodia ‘long column’, the preferences of New Zealand’s native and introduced insect pollinators in an extensive observational study, the results of which I further tested using a subsequent manipulative experiment of petal colour (according to human vision) at the Christchurch Botanical Gardens Sampling at the Christchurch Botanical Gardens, University of Canterbury, and Port Hills across a four month observation period (January – April 2012), revealed that native pollinators preferred white native flowers and exotic pollinators preferred not-white exotic flowers when data were grouped according to insect provenance. A more detailed visit-level analysis found that two native bees, Hylaeus and Leioproctus, showed a significant preference for native flowers; the exotic bees, Apis mellifera and Bombus species, preferred purple over white flowers; and Melangyna novaezelandiae (a native hoverfly) preferred white over yellow. However, a series of experimental arrays to present controlled choices between pairs of flower types at the Christchurch Botanical Gardens (14 December 2012 – 22 January 2013) did not find significant preferences by native or exotic insect pollinators between white and yellow flowers. This may have been a result of the plant species chosen, as a correlation between pollinator preference and plant species has been shown elsewhere. Visitation to experimental arrays was both low and highly skewed, with over half of all visits made by Lasioglossum bees and 615 of the 669 visits made by native species. This may have meant that lack of significant results were representing the choices of native insects generally and Lasioglossum bees specifically. A bagging experiment from 30 January 2012 – 16 February 2012 demonstrated the dependence of the undescribed native orchid species, Gastrodia ‘long column’, upon pollinating animals. Fruit set of most plants worldwide depends upon pollination (by wind or animal-transfer of pollen). In this case study final fruit sets were significantly reduced on bagged inflorescences, while open flowers had surprisingly high natural fruit sets (>75%). A week of observations (29 January 2012 – 6 February 2012) revealed that Gastrodia ‘long column’ was predominantly visited by Lasioglossum bees, and remarkably bee numbers were high enough in a residential property in the middle of Christchurch city for high fruit set on unmanipulated plants. The results of my thesis indicate that pollinators are important in the reproductive system of Gastrodia ‘long column’, suggesting that other previously overlooked plant species may also rely upon insect pollinators. Furthermore, the relative importance of native pollinating insects is high for native plants even when examined in an urban setting. New Zealand pollinators have preferences for certain floral traits which show trends when grouped broadly, but vary when considered at the insect species level. This contrasts with traditional views of unspecialised insect pollinators which lack preferences in regards to the plants they visit. Further work which serves to increase current understanding of the underlying mechanisms of pollination specialisation in New Zealand may wish to focus on single insect species. By identifying particular preferences of pollinators and the underlying ‘native’ traits selected for, alternative options to crop pollination may be found, targeted management strategies implemented, and the strength of the relationship between pollinator preferences and the traits of the plants they visit determined.

Solitary bees are important pollinators of crops, with species in the family Megachilidae (mason bees) being used for orchard pollination. Commercial movement of these bees also moves their microbiota, including bacterial endosymbionts capable of reproductive manipulation. To test for presence of these bacteria, I screened commercially available species of US orchard pollinators and locally captured solitary bees from Kentucky. I also set up mason bee boxes in five apple orchards to examine recruitment of local pollinators. I conducted 454-pyrosequencing to determine bacterial diversity within four species followed by diagnostic PCR of 30 collected species (184 individuals) to determine infection frequency of selected endosymbionts. Consistent with literature, Wolbachia was abundant in these bees. I also found two other endosymbiotic bacteria, Sodalis (previously undetected in Hymenoptera), and Arsenophonus. Diagnostic screening demonstrated that Sodalis was present at moderate frequency in Osmia aglaia, whereas Arsenophonus was present at low frequency in Lasioglossum pilosum. Neither was found in other bees, but three bee species were infected with Sodalis-like endosymbionts. Although recruitment of bees to bee boxes was ineffective, I was able to independently collect native orchard pollinating Andrenidae species. My results demonstrate that other endosymbionts capable of reproductive manipulation, besides Wolbachia, are present in bees.

Honeybees are used as a major agricultural input around the world and their pollination services have been valued at US$14.6 billion to the United States alone. Dramatic declines in honeybee populations around the globe, however, questioned the sustainability of this reliance on a single pollinator species. In this study, I investigated the response of wild pollinator communities to declining honeybee density and changing land use intensity to determine the potential of wild pollinators to compensate for honeybee loss in an increasingly human-modified environment. I generated a gradient of declining honeybee density using increasing distances from commercial bee hives, and conducted flower observations on experimentally-grown plants across this gradient. I investigate how declining honeybee densities and intensifying land use combine to influence the composition of the pollinator community as a whole, then go on to explore individual trends in the most common pollinator species. I then analyze how this impacts the transport of viable pollen by the pollinator community and determine how these changes alter seed set in several common plant species. I then change my focus away from the composition of the pollinator community, and instead investigate how declining honeybee densities and land-use intensification influence the structuring of interactions between plants and pollinators within the community. I identify the pollen species carried by pollinators, and use this to construct a network of pollination interactions. I then use this network to analyze how changes in the way species interact influences the pollination services delivered by the pollinator community to different plant groups (weeds, native plants, and crop species). My findings show that honeybee declines may have a large impact on community structure and interactions within pollination systems. I observed a significant shift in the wild pollinator community composition as honeybee densities declined, from a generally bee/hoverfly dominated community to one more dominated by large flies. This was associated with a significant decline in the total pollen load transported by the community, indicating that pollination services may suffer in the absence of honeybees. As honeybee densities declined, however, I also observed a shift toward greater specialisation of pollinators on abundant resources, increased pollinator constancy, and a higher viability rate of the pollen transported. These findings show that although the total amount of pollen transported by the community declined as honeybee densities decreased, the probability of this pollen transport resulting in effective pollination likely increased. Thus, I observed no decrease in seed set with honeybee declines in any of the three plant species tested, and one of these even showed a significant increase. Finally, I also demonstrated that this change differentially affected different plant types, and that the extent of changes to each plant species differed between land-use types. This reflected changes in the relative abundance of pollen types in different land uses, with greater specialisation in the absence of honeybees disproportionately benefiting common species. These findings have strong implications for several contemporary issues in pollination biology, both locally within New Zealand and on a global scale. These are discussed in the following sections. Finally, I conclude by discussing the implications of this research on several contemporary issues in pollination biology, namely the ability for wild pollinators to compensate for honeybee declines, the impact of honeybees on natural new Zealand ecosystems, the contribution of honeybees to invasive weed pollination and finally the management of surrounding land use types to maximize the effectiveness of wild pollinators.

Rapid development of bacterial resistance and multiresitance to conventional antibiotics has resulted in an intensive search for alternative antimicrobial agents. Antimicrobial peptides (AMPs) belong to promising anti-infective candidates since they do not development bacterial resistance. They kill microbes by disturbing or permeabilizing the cytoplasmic membrane, or may target putative key intracellular compartments. Their advantages include fast action and selectivity between prokaryotic and eukaryotic cells. We have isolated several novel AMPs from the venom of wild bees: halictines (HAL-1 and HAL-2) from Halictus sexcinctus, lasiocepsin (Las) from Lasioglossum laticeps and macropin (MAC-1) from Macropis fulvipes. They are active against Gram-positive and Gram- negative bacteria and against yeast Candida albicans. While halictines and macropin have moderate hemolytic activity, Las shows no hemolytic activity. A novel AMP was isolated also from the mucus of Xiphydria camelus. This AMP belongs to the category of insect defensins. It contains 55 amino acid residues, three disulphide bridges and its C-terminus is amidated. CD and NMR studies of HAL-1, HAL-2 and MAC-1 revealed propensity to form amphipathic α-helical structure in the presence of sodium dodecyl sulfate or trifluoroethanol. For the...