Next Article in Journal
Resistance to Bt Maize by Western Corn Rootworm: Effects of Pest Biology, the Pest–Crop Interaction and the Agricultural Landscape on Resistance
Next Article in Special Issue
Ensemble Models Predict Invasive Bee Habitat Suitability Will Expand under Future Climate Scenarios in Hawai’i
Previous Article in Journal
Abundance of Entomopathogenic Fungi in Leaf Litter and Soil Layers in Forested Habitats in Poland
Previous Article in Special Issue
Supporting Bees in Cities: How Bees Are Influenced by Local and Landscape Features
Article

Joint Impacts of Drought and Habitat Fragmentation on Native Bee Assemblages in a California Biodiversity Hotspot

1
Section of Ecology, Behavior and Evolution, Division of Biological Sciences, University of California—San Diego, 9500 Gilman Drive, La Jolla, CA 92037, USA
2
Department of Ecology and Evolutionary Biology, University of Toronto, 25 Willcocks Street, Toronto, ON M5S 3B2, Canada
3
Department of Biological Sciences, National University of Singapore, 14 Science Drive 4, Singapore 117543, Singapore
*
Author to whom correspondence should be addressed.
Academic Editors: Theresa Pitts-Singer, Lindsie M. McCabe and Jonathan B. Koch
Insects 2021, 12(2), 135; https://doi.org/10.3390/insects12020135
Received: 21 December 2020 / Revised: 28 January 2021 / Accepted: 2 February 2021 / Published: 5 February 2021
(This article belongs to the Special Issue Non-Apis Pollinators and Global Change)
Global climate change is causing more frequent and severe droughts, which can have serious impacts on our environment. To examine how a severe drought in 2014 impacted wild bees in scrub habitats of San Diego, California, we compared bee samples collected before and after the drought. We also investigated whether habitat loss and fragmentation worsened the impacts of drought on wild bees by comparing samples collected from large natural reserves to those from small fragments of scrub habitat embedded in urban areas. Samples collected after the drought contained fewer bee species and fewer individual bees of most species, indicating that bee populations suffered losses during the drought. However, after-drought samples contained large numbers of Dialictus sweat bees, indicating that some bee species benefitted from environmental conditions present during the drought. The impact of drought on the composition of bee samples was three fold higher than the impact of habitat fragmentation, and habitat fragmentation did not appear to have exacerbated the impacts of drought. Our findings highlight the importance of studying how impacts of climate change compare with impacts of habitat loss and other threats to biodiversity conservation.
Global climate change is causing more frequent and severe droughts, which could have serious repercussions for the maintenance of biodiversity. Here, we compare native bee assemblages collected via bowl traps before and after a severe drought event in 2014 in San Diego, California, and examine the relative magnitude of impacts from drought in fragmented habitat patches versus unfragmented natural reserves. Bee richness and diversity were higher in assemblages surveyed before the drought compared to those surveyed after the drought. However, bees belonging to the Lasioglossum subgenus Dialictus increased in abundance after the drought, driving increased representation by small-bodied, primitively eusocial, and generalist bees in post-drought assemblages. Conversely, among non-Dialictus bees, post-drought years were associated with decreased abundance and reduced representation by eusocial species. Drought effects were consistently greater in reserves, which supported more bee species, than in fragments, suggesting that fragmentation either had redundant impacts with drought, or ameliorated effects of drought by enhancing bees’ access to floral resources in irrigated urban environments. Shifts in assemblage composition associated with drought were three times greater compared to those associated with habitat fragmentation, highlighting the importance of understanding the impacts of large-scale climatic events relative to those associated with land use change. View Full-Text
Keywords: coastal sage scrub; global climate change; habitat loss and fragmentation; pollinators; California drought; Lasioglossum Dialictus coastal sage scrub; global climate change; habitat loss and fragmentation; pollinators; California drought; Lasioglossum Dialictus
Show Figures

Figure 1

MDPI and ACS Style

Hung, K.-L.J.; Sandoval, S.S.; Ascher, J.S.; Holway, D.A. Joint Impacts of Drought and Habitat Fragmentation on Native Bee Assemblages in a California Biodiversity Hotspot. Insects 2021, 12, 135. https://doi.org/10.3390/insects12020135

AMA Style

Hung K-LJ, Sandoval SS, Ascher JS, Holway DA. Joint Impacts of Drought and Habitat Fragmentation on Native Bee Assemblages in a California Biodiversity Hotspot. Insects. 2021; 12(2):135. https://doi.org/10.3390/insects12020135

Chicago/Turabian Style

Hung, Keng-Lou J., Sara S. Sandoval, John S. Ascher, and David A. Holway. 2021. "Joint Impacts of Drought and Habitat Fragmentation on Native Bee Assemblages in a California Biodiversity Hotspot" Insects 12, no. 2: 135. https://doi.org/10.3390/insects12020135

Find Other Styles
Note that from the first issue of 2016, MDPI journals use article numbers instead of page numbers. See further details here.

Article Access Map by Country/Region

1
Back to TopTop