Hylaeus anthracinus (Hymenoptera: Colletidae) is an endemic Hawaiian bee and candidate for federal protection as an endangered species. On Oahu, H. anthracinus populations are restricted to a few isolated populations in fragments of endangered coastal strand habitat. Prior to this study, knowledge of H. anthracinus natural history was based largely on observations from closely related bees, but little was known regarding the specific nest ecology, or immature development needed to design effective and sustainable conservation management methodologies.

1. Nest ecology of an endemic Hawaiian bee, Hylaeus anthracinus
(Hymenoptera: Colletidae), and implications for conservation
Jason R. Graham1, Sheldon Plentovich2, and Cynthia B. A. King3
1University of Hawaiʻi at Mānoa, College of Tropical Agriculture and Human Resources, Department of Plant and Environmental Protection Sciences
2United States Fish and Wildlife Service, Pacific Islands Coastal Program
3Hawaiʻi Department of Land and Natural Resources, Division of Forestry and Wildlife
Hylaeus anthracinus (Hymenoptera: Colletidae) is an endemic Hawaiian bee and
candidate for federal protection as an endangered species. On Oahu, H. anthracinus
populations are restricted to a few isolated populations in fragments of endangered
coastal strand habitat. Prior to this study, knowledge of H. anthracinus natural history
was based largely on observations from closely related bees, but little was known
regarding the specific nest ecology, or immature development needed to design
effective and sustainable conservation management methodologies.
Objective: Our goal was to gather specific details surrounding the nest ecology
and natural history of H. anthracinus, in order to develop and apply conservation
management methodologies to increase the populations of this candidate
endangered species.
A
BA Turtle Bay B Sandy Beach
Activity level of two Hylaeus anthracinus populations measured as average
landings per minute during timed point counts at Turtle Bay or Sandy Beach
field sites from Dec 2014-Jan 2016.
Hylaeus anthracinus
mating
Endangered coastal
strand habitat
Some females nest
in coral rubble
Others nest in
hollow plant stems
Oahu, Hawaii

2. B
A
C
D
A B DC
Acknowledgements: This project was funded by the Department of Defense Legacy Resource Management Program. We thank Karl Magnacca and
Kapua Kawelo of the O‘ahu Army Natural Resources Program; Joseph Schwagerl and Kenzie Jackson Letchworth of US Fish &Wildlife Service National Wildlife
Refuge; William Haines of the University of Hawaiʻi at Mānoa for support and assistance in carrying out work for this project.
Potential risks to H. anthracinus were observed
during this study including: non-native bees as nest
competitors; human activities; climatic events;
pests/predators; and bee pathogens.
Contact Information:
Jason R. Graham, PhD
University of Hawaiʻi at Mānoa
jrgraham@hawaii.edu
(352) 519-9592
Approach: We monitored study sites to determine Hylaeus population size, activity level, community structure, and use of resources. Populations were
measured as timed point counts of bee landings within site. We collected materials suspected of containing nests for dissection, measured the dissected nest
parameters, and described the architecture. We transferred developing immature bees into queen cups using grafting tools and observed development on a daily
basis. The data and insights we gathered in this study facilitated the design of artificial nest sites now being tested as conservation management tools.
Immature bees were reared to adult in
order to describe the development of
these bees, and verify the species
corresponding to each dissected nest.
Eggs developed to adults in ≥29 days.
Hylaeus anthracinus utilize the
coastal plants Scaevola sericea (left)
and Heliotropium foertherianum
(right) for both forage and nest
resources.
Outcome: Nest dissections provided an understanding of the natural nest architecture and ecology of native
Hylaeus. These data guided the development of artificial nest sites, that have been accepted by H. anthracinus in
field trials. Artificial nest sites can potentially strengthen weak native bee populations, repopulate high priority
managed areas, and exclude ants and other crawling pests and predators.