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Hamutahl Cohen
Environmental Studies Department, University of California Santa Cruz, Santa Cruz, USA

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Article
Published: 04 August 2020 in Urban Ecosystems
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Although urban gardens are often celebrated for supporting bee abundance and diversity within cities, little is known about how garden management and urbanization levels influence bee foraging behavior and ability to utilize resources within these landscapes. Specifically, the preferences and diet breadth of bees may depend critically on local and landscape conditions in human-managed, urban environments. To understand how foraging patterns and pollen preferences are influenced by urban landscape composition, we first examined if bees visit plants grown within urban gardens and second assessed the relationships between local floral resources, urban land cover, and pollen collection patterns, focusing on 20 community gardens across 125 km of the California central coast. We targeted a well-studied, essential native pollinator in this ecoregion, Bombus vosnesenskii, and analyzed pollen on the bodies of individuals collected in our study gardens to compare their contents to local and landscape garden composition factors. We found that greater landscape-level urban cover and greater plant species richness in the garden both drove higher within-garden pollen collection. We also found that B. vosnesenskii preferred ornamental plant species over highly available crop species in the gardens. Our study indicates that landscapes that support plant diversity, including both ornamental plants and sustenance-oriented food crops, promote greater within-garden pollen collection patterns, with likely benefits for urban garden food production.

ACS Style

Megan O’Connell; Zachariah Jordan; Erin McGilvray; Hamutahl Cohen; Heidi Liere; Brenda B. Lin; Stacy M. Philpott; Shalene Jha. Reap what you sow: local plant composition mediates bumblebee foraging patterns within urban garden landscapes. Urban Ecosystems 2020, 1 -14.

AMA Style

Megan O’Connell, Zachariah Jordan, Erin McGilvray, Hamutahl Cohen, Heidi Liere, Brenda B. Lin, Stacy M. Philpott, Shalene Jha. Reap what you sow: local plant composition mediates bumblebee foraging patterns within urban garden landscapes. Urban Ecosystems. 2020; ():1-14.

Chicago/Turabian Style

Megan O’Connell; Zachariah Jordan; Erin McGilvray; Hamutahl Cohen; Heidi Liere; Brenda B. Lin; Stacy M. Philpott; Shalene Jha. 2020. "Reap what you sow: local plant composition mediates bumblebee foraging patterns within urban garden landscapes." Urban Ecosystems , no. : 1-14.

Article
Published: 10 July 2020 in Urban Ecosystems
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It is often argued that biodiversity and ecosystem functioning are linked by both habitat and species composition, and that this relationship is particularly critical for mobile ecosystem service providers. This may be especially true for pollinators, which are essential for the reproduction of the majority of flowering plant species, are highly mobile, and can exhibit dramatically different foraging behaviors across ecosystems. Understanding how habitat and community composition impact pollination is especially relevant in urban environments where pollinators can promote food security. We examined the relationships between local resource density, landscape composition, pollinator abundance and richness, and pollination services in an urban agricultural system spanning >125 km of the California central coast. We used a replicated, experimental approach to evaluate the reproductive success of jalapeño peppers across urban gardens and conducted a greenhouse experiment to evaluate the benefits of insect-mediated pollination to pepper reproduction. In the greenhouse, we found that jalapeño fruit weight and seed number was significantly greater with insect-mediated pollination than without. In the field, we found that jalapeño seed number increased significantly with herbaceous (weed, crop, and ornamental) plant richness and the number of perennial trees and shrubs at the site level, but decreased with the amount of natural landscape cover. We also found that higher pollinator richness enhanced seed number in floral-dense gardens, likely due to the greater functional complementarity of a more diverse pollinator community. Furthermore, there was a positive relationship between pollinator abundance and seed number, but it weakened in gardens with more flowers, likely through lower per-plant pollinator visitation in the presence of competing floral resources. As in past studies, we found that mulch had a negative impact on pollinator abundance, highlighting that abiotic factors commonly managed by gardeners can directly impact ecosystem service providers. This study demonstrates that local conditions can significantly influence ecosystem service provision and that urban gardeners need to optimize for both pollinator richness and floral resource availability to achieve optimal pollination.

ACS Style

Hamutahl Cohen; Stacy M. Philpott; Heidi Liere; Brenda B. Lin; Shalene Jha. The relationship between pollinator community and pollination services is mediated by floral abundance in urban landscapes. Urban Ecosystems 2020, 24, 275 -290.

AMA Style

Hamutahl Cohen, Stacy M. Philpott, Heidi Liere, Brenda B. Lin, Shalene Jha. The relationship between pollinator community and pollination services is mediated by floral abundance in urban landscapes. Urban Ecosystems. 2020; 24 (2):275-290.

Chicago/Turabian Style

Hamutahl Cohen; Stacy M. Philpott; Heidi Liere; Brenda B. Lin; Shalene Jha. 2020. "The relationship between pollinator community and pollination services is mediated by floral abundance in urban landscapes." Urban Ecosystems 24, no. 2: 275-290.

Invertebrate microbiology
Published: 22 June 2020 in Microbial Ecology
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Wild bees encounter environmental microbes while foraging. While environmental context affects bee diversity, little is known about it how affects the wild bee microbiome. We used field surveys in 17 urban gardens to examine whether and how variation in local and landscape habitat features shapes the microbiome of the solitary Blue Orchard Bee, Osmia lignaria. We installed O. lignaria cocoons at each site, allowed bees to emerge and forage, then collected them. We measured local features of gardens using vegetation transects and landscape features with GIS. We found that in microbiome composition between bee individuals varied by environmental features such as natural habitat, floral resources, and bee species richness. We also found that environmental features were associated with the abundance of bacterial groups important for bee health, such as Lactobacillus. Our study highlights complex interactions between environment context, bee species diversity, and the bee-associated microbes.

ACS Style

Hamutahl Cohen; Quinn S. McFREDERICK; Stacy M. Philpott. Environment Shapes the Microbiome of the Blue Orchard Bee, Osmia lignaria. Microbial Ecology 2020, 80, 897 -907.

AMA Style

Hamutahl Cohen, Quinn S. McFREDERICK, Stacy M. Philpott. Environment Shapes the Microbiome of the Blue Orchard Bee, Osmia lignaria. Microbial Ecology. 2020; 80 (4):897-907.

Chicago/Turabian Style

Hamutahl Cohen; Quinn S. McFREDERICK; Stacy M. Philpott. 2020. "Environment Shapes the Microbiome of the Blue Orchard Bee, Osmia lignaria." Microbial Ecology 80, no. 4: 897-907.

Journal article
Published: 01 January 2020 in Ecology and Society
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ACS Style

Stacy M. Philpott; Monika H. Egerer; Peter Bichier; Hamutahl Cohen; Roseann Cohen; Heidi Liere; Shalene Jha; Brenda B. Lin. Gardener demographics, experience, and motivations drive differences in plant species richness and composition in urban gardens. Ecology and Society 2020, 25, 1 .

AMA Style

Stacy M. Philpott, Monika H. Egerer, Peter Bichier, Hamutahl Cohen, Roseann Cohen, Heidi Liere, Shalene Jha, Brenda B. Lin. Gardener demographics, experience, and motivations drive differences in plant species richness and composition in urban gardens. Ecology and Society. 2020; 25 (4):1.

Chicago/Turabian Style

Stacy M. Philpott; Monika H. Egerer; Peter Bichier; Hamutahl Cohen; Roseann Cohen; Heidi Liere; Shalene Jha; Brenda B. Lin. 2020. "Gardener demographics, experience, and motivations drive differences in plant species richness and composition in urban gardens." Ecology and Society 25, no. 4: 1.

Journal article
Published: 30 December 2019 in Sustainability
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Across urban environments, vegetated habitats provide refuge for biodiversity. Gardens (designed for food crop production) and nurseries (designed for ornamental plant production) are both urban agricultural habitats characterized by high plant species richness but may vary in their ability to support wild pollinators, particularly bees. In gardens, pollinators are valued for crop production. In nurseries, ornamental plants rarely require pollination; thus, the potential of nurseries to support pollinators has not been examined. We asked how these habitats vary in their ability to support wild bees, and what habitat features relate to this variability. In 19 gardens and 11 nurseries in California, USA, we compared how local habitat and landscape features affected wild bee species abundance and richness. To assess local features, we estimated floral richness and measured ground cover as proxies for food and nesting resources, respectively. To assess landscape features, we measured impervious land cover surrounding each site. Our analyses showed that differences in floral richness, local habitat size, and the amount of urban land cover impacted garden wild bee species richness. In nurseries, floral richness and the proportion of native plant species impacted wild bee abundance and richness. We suggest management guidelines for supporting wild pollinators in both habitats.

ACS Style

Monika Egerer; Jacob Cecala; Hamutahl Cohen. Wild Bee Conservation within Urban Gardens and Nurseries: Effects of Local and Landscape Management. Sustainability 2019, 12, 293 .

AMA Style

Monika Egerer, Jacob Cecala, Hamutahl Cohen. Wild Bee Conservation within Urban Gardens and Nurseries: Effects of Local and Landscape Management. Sustainability. 2019; 12 (1):293.

Chicago/Turabian Style

Monika Egerer; Jacob Cecala; Hamutahl Cohen. 2019. "Wild Bee Conservation within Urban Gardens and Nurseries: Effects of Local and Landscape Management." Sustainability 12, no. 1: 293.

Journal article
Published: 19 April 2019 in Insects
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Urban ecosystems, as mosaics of residential, industrial, commercial, and agricultural land, present challenges for species survival due to impervious surface, degradation, fragmentation, and modification of natural habitat, pollution, and introduced species. Some urban habitats, such as community gardens, support biodiversity and promote ecosystem services. In gardens, local factors (e.g., vegetation, groundcover) and landscape surroundings (e.g., agriculture, built or impervious cover) may influence species abundance, richness, and functional traits that are present. We examined which local and landscape factors within 19 community gardens in the California central coast influence ground beetle (Carabidae) activity density, species richness, functional group richness, and functional traits-body size, wing morphology, and dispersal ability. Gardens with higher crop richness and that are surrounded by agricultural land had greater carabid activity density, while species and functional group richness did not respond to any local or landscape factor. Gardens with more leaf litter had lower carabid activity, and gardens with more leaf litter tended to have more larger carabids. Changes in local (floral abundance, ground cover) and landscape (urban land cover) factors also influenced the distribution of individuals with certain wing morphology and body size traits. Thus, both local and landscape factors influence the taxonomic and functional traits of carabid communities, with potential implications for pest control services that are provided by carabids.

ACS Style

Stacy M. Philpott; Simone Albuquerque; Peter Bichier; Hamutahl Cohen; Monika H. Egerer; Claire Kirk; Kipling W. Will. Local and Landscape Drivers of Carabid Activity, Species Richness, and Traits in Urban Gardens in Coastal California. Insects 2019, 10, 112 .

AMA Style

Stacy M. Philpott, Simone Albuquerque, Peter Bichier, Hamutahl Cohen, Monika H. Egerer, Claire Kirk, Kipling W. Will. Local and Landscape Drivers of Carabid Activity, Species Richness, and Traits in Urban Gardens in Coastal California. Insects. 2019; 10 (4):112.

Chicago/Turabian Style

Stacy M. Philpott; Simone Albuquerque; Peter Bichier; Hamutahl Cohen; Monika H. Egerer; Claire Kirk; Kipling W. Will. 2019. "Local and Landscape Drivers of Carabid Activity, Species Richness, and Traits in Urban Gardens in Coastal California." Insects 10, no. 4: 112.

Journal article
Published: 23 October 2017 in Environmental Entomology
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Apocephalus borealis phorid flies, a parasitoid of bumble bees and yellow jacket wasps in North America, was recently reported as a novel parasitoid of the honey bee Apis mellifera Linnaeus (Hymenoptera: Apidae). Little is known about the ecology of this interaction, including phorid fecundity on bee hosts, whether phorid-bee parasitism is density dependent, and which local habitat and landscape features may correlate with changes in parasitism rates for either bumble or honey bees. We examined the impact of local and landscape drivers and host abundance on phorid parasitism of A. mellifera and the bumble bee Bombus vosnesenskii Radoszkowski (Hymenoptera: Apidae). We worked in 19 urban gardens along the North-Central Coast of California, where phorid parasitism of honey bees was first reported in 2012. We collected and incubated bees for phorid emergence, and surveyed local vegetation, ground cover, and floral characteristics as well as land cover types surrounding gardens. We found that phorid parasitism was higher on bumble bees than on honey bees, and phorids produced nearly twice as many pupae on individual bumble bee hosts than on honey bee hosts. Parasitism of both bumble and honey bees increased with abundance of honey bees in a site. Differences in landscape surroundings did not correlate with parasitism, but local factors related to bee resource provisioning (e.g., tree and shrub abundance) positively correlated with increased parasitism. This research thus helps to document and describe conditions that may have facilitated phorid fly host shift to honey bees and further elucidate how resource provisioning in urban gardens influences bee–parasite interactions.

ACS Style

Hamutahl Cohen; Robyn D Quistberg; Stacy M Philpott. Vegetation Management and Host Density Influence Bee–Parasite Interactions in Urban Gardens. Environmental Entomology 2017, 46, 1313 -1321.

AMA Style

Hamutahl Cohen, Robyn D Quistberg, Stacy M Philpott. Vegetation Management and Host Density Influence Bee–Parasite Interactions in Urban Gardens. Environmental Entomology. 2017; 46 (6):1313-1321.

Chicago/Turabian Style

Hamutahl Cohen; Robyn D Quistberg; Stacy M Philpott. 2017. "Vegetation Management and Host Density Influence Bee–Parasite Interactions in Urban Gardens." Environmental Entomology 46, no. 6: 1313-1321.

Journal article
Published: 17 October 2017 in Annual Review of Environment and Resources
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ACS Style

Carol Shennan; Timothy J. Krupnik; Graeme Baird; Hamutahl Cohen; Kelsey Forbush; Robin Lovell; Elissa M. Olimpi. Organic and Conventional Agriculture: A Useful Framing? Annual Review of Environment and Resources 2017, 42, 317 -346.

AMA Style

Carol Shennan, Timothy J. Krupnik, Graeme Baird, Hamutahl Cohen, Kelsey Forbush, Robin Lovell, Elissa M. Olimpi. Organic and Conventional Agriculture: A Useful Framing? Annual Review of Environment and Resources. 2017; 42 (1):317-346.

Chicago/Turabian Style

Carol Shennan; Timothy J. Krupnik; Graeme Baird; Hamutahl Cohen; Kelsey Forbush; Robin Lovell; Elissa M. Olimpi. 2017. "Organic and Conventional Agriculture: A Useful Framing?" Annual Review of Environment and Resources 42, no. 1: 317-346.