Project Number: 2080-21000-019-047-R
Project Type: Reimbursable Cooperative Agreement
Start Date: Mar 1, 2022
End Date: Jan 30, 2024
The Mojave poppy bee (Perdita meconis) is an extremely rare poppy specialist species native to Nevada, Arizona, and Utah with a historic range that includes Clark County and a few adjacent counties. Recently, precipitous declines of the Mojave poppy bee have been observed on dwarf bear poppy (Arctomecon humilis) populations in southwestern Utah. Given these precipitous declines, it is essential to determine the status of this bee in southern Nevada where it is known to exist in some Las Vegas bear poppy (Arctomecon californica) and prickly poppy (Argemone spp.) populations. To determine the status of the Mojave poppy bee in Clark County, (COUNTY) will work with USDA-ARS Pollinating Insects Research Unit (AGENCY) to conduct a systematic, across-the-flowering season survey focused on Las Vegas bear poppy populations, and secondarily, on prickly poppy populations. Such an effort has been initiated on Bureau of Land Management lands in the County, but adjacent public lands also need to be surveyed in order to get a complete picture of species distributions and status. AGENCY shall assist COUNTY by conducting systematic surveys for Mojave poppy bee, and by conducting pollination studies, on public lands throughout the County. We will conduct systematic surveys for the Mojave poppy bee primarily on Las Vegas bear poppy populations with emphasis on Arctomecon populations not studied in previous assessments of pollinators. Limited time will be spent on prickly poppy sites, especially ones where the bee was previously found. The study design will also allow evaluation of overall pollinator visitation to the Las Vegas bear poppy and the degree to which this provides effective pollination, a matter of interest given the concern over the plant’s status.
Surveys will be conducted throughout the flowering season (typically mid-March to the end of May) on a biweekly basis by a team of two. Each survey will begin early in the morning (as early as 6 am depending on temperatures) and continue until afternoon at the end of daily bee activity. For each survey, two methods will be employed, observation and sampling. For observations, 10 plants in bloom will be selected across the population. As each plant in flower is located, observers will record numbers of flowers in bloom as well as the numbers of buds and fruits. Bees visiting the flowers will be observed for five minutes and the total number of Perdita visits by males and females will be recorded, as well as counts of the number of Africanized honeybees, and numbers of other native pollinators. The other method of surveying, sampling, will follow directly after the observation event, which is necessary to determine whether the Perdita observed are in fact the Mojave Poppy Bee and to identify the other potential pollinators of the Las Vegas bear poppy. Because identifications of Perdita species are not possible in the field, vouchers are needed to confirm the identity and to potentially determine genetic diversity. By collecting males rather than potentially nesting females, collections will have negligible effect on the population. If potential Perdita meconis is found at a population, up to 20 males will be collected per site. These will be used to verify the proportion of Perdita that are the Mojave poppy bee. They will also be used for DNA to assess genetic population structure. Vouchers will be pinned and labelled with unique scannable matrix codes, and the data, including GPS recorded coordinates, will be entered into the National Pollinating Insects Collection database. Due to the sensitive nature of both the bees and the listed plants, records will be withheld, not served on GBIF or SCAN, or specific location data will be withheld. To determine if A. californica populations receive sufficient pollination, a pollination study will be conducted on five robust A. californica populations. Populations will be chosen to cover a range in proximity to developed habitat to determine if landscape characteristics, namely human development, correlate with pollination limitation. Habitat characteristics around populations will be quantified prior to the field season to aid in the site selection process. Input from county and state stakeholders will also be considered in the site selection process. Sites will be visited multiple times throughout the bloom period to monitor which flowers are receptive to pollination. Three pollination treatments will then be applied to plants: autogamy (self-pollination; flower bagged to exclude insect pollinators), xenogamy (cross-pollination; hand pollinated from a different plant), and open-pollination (flower open to insect pollinators), and pollination limitation determined via fruit set.