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Mojave Poppy Bee
Perdita meconis
NatureServe conservation status
Global (G-rank): G2
State (S-rank): SX
External links
Phenology
P. meconis life cycle and behavior is tied closely to the poppies on which it depends for forage. Adult bee activity occurs around early April, coinciding with poppy bloom, and lasts several weeks to allow for mating, nest building and egg laying (Cornelisse, 2018). Larvae hatch and overwinter before pupating and emerging as adults the following spring. Species of this genus exhibit a behavior known as bet hedging, where individuals enter an extended diapause for 2-3 years in response to environmental aridity; in this way, they ensure emergence as adults during the blooming of their host plants (Portman et al., 2016). For this reason, P. meconis should only be expected in years following winter rains.
Species range
This species is known only from the eastern Mojave Desert; its historic range includes Clark County, Nevada in the Lake Mead National Recreational Area, and Washington County, Utah. In the original description of P. meconis, specimens from California were included, and additional sightings from Arizona have been reported; however, these historic occurrences are uncertain (Cornelisse, 2018). Unfortunately, the historic range of this species represents a much larger area than the species currently occupies. P. meconis has been driven to extinction within its Utah range, a fate likely to be shared by any populations in Arizona and California due to extreme habitat fragmentation and population isolation (Cornelisse, 2018; Portman et al., 2018). According to the 2018 petition to list this species under the ESA, only seven fragmented populations remain within the confines of Lake Mead National Recreational Area and adjacent BLM lands in Nevada (Cornelisse, 2018). More recent studies have found P. meconis at only three sites within Clark County, though further surveys are recommended to account for difficulty detecting bees in extended diapause (Chanprame et al., 2024).
Habitat
P. meconis is a habitat specialist with strict requirements for both foraging and nesting. The relatively small size and foraging behavior of this species likely limit its foraging range to a matter of meters, which is typical of similar desert plant specialists (Cornelisse, 2018; Danforth, 1989; Greenleaf et al., 2007). This in turn means that P. meconis requires dense patches of bear-poppies in order to meet its foraging needs. Additionally, it requires open patches of gypsum soil nearby to poppy patches in order to nest. Gypsum-derived soils in the Mojave desert often play host to cryptogamic crusts that prevent erosion and increase nitrogen availability, improving habitat quality for the bear-poppies, and by proxy, P. meconis (Harper & Van Buren, 2004; Sardiñas & Kremen, 2014).
Food habits
P. meconis, like most species of the genus Perdita, is oligolectic; that is, they exhibit a narrow preference for the pollen of only a handful of species. As noted above, the species upon which P. meconis forages and depend are the dwarf and Las Vegas bear-poppies. Most foraging behavior is undertaken by females near to a nest site in order to provision pollen necessary for larval development. Female bees collect pollen for between 30 seconds to several minutes, during which time they often visit multiple flowers on multiple plants (Hickerson, 1998; Tepedino et al., 2014). Female bees collect enough pollen every day to provision one brood cell, laying a single egg upon a ball of pollen which will serve as a food source for the developing larvae (Cornelisse, 2018; Danforth, 1989). The preference for bear-poppy pollen exhibited by this species is so strong that if the host plants are not blooming, P. meconis will not forage pollen from different plant species; it is for this reason that they have adapted delayed emergence to coincide with the blooming of the bear-poppies.
Ecology
The relationship between P. meconis and its host plants is mutualistic: while the plant is a crucial food source for the bees, P. meconis is an excellent pollinator of the bear-poppies. Additional bee behaviors pollinate the flowers beyond just foraging: male bees moving amongst poppy flowers will often react aggressively to other males, resulting in tumbling that spreads pollen between flowers (Portman et al., 2019). Additionally, P. meconis mates in the flower of the bear-poppy itself, with the pair often contacting the stigma to complete pollination (Hickerson, 1998). The fact that the life history and behavior of the bee is so closely tied to the bear poppy suggests that the bee likely once occurred across the entire range of the bear-poppy (Hickerson, 1998). P. meconis is such an important pollinator to its host species that its absence is now considered a critical threat to the continued survival of both bear-poppy species (Cornelisse, 2018); indeed, when it was first described, this bee was the main pollinator of the dwarf bear-poppy in Utah (Griswold, 1993). Though other pollinator species, including the introduced honey bee, visit bear-poppy flowers, many are generalists that visit many plant species and are therefore less effective pollinators compared to the specialist P. meconis (Harper et al., 2001).
Threats or limiting factors
Threats to this species include a number of anthropogenic modifications to the environment of P. meconis and its host plants. Perhaps the most dramatic is the impact urban development has had on fragmenting stretches of land that previously provided connected habitat throughout the bee’s range. Besides the impacts of direct mortality on bee populations as host plants are removed to make way for development and other human activities, the remaining fragmented patches of habitat pose a number of challenges to bee survival. The relatively short foraging distance of this species means it requires interconnected patches of flowers in order to survive; most solitary bees require nesting and sufficient host plant habitat to be within 100 m of each other (Zurbuchen et al., 2010b). When this distance increases, female bees aren’t able to provision as many brood cells, and fewer bees are born every year (Zurbuchen et al., 2010a). Reducing the size of floral patches and increasing distance between them therefore has a dramatic impact on bee population dynamics. Even small increases in the distance between floral resources significantly reduces pollination rates, and may result in a failure to provision enough pollen for larval development (Cornelisse, 2010; Greenleaf et al., 2007). Fragmentation also reduces gene flow and population viability, impacting the survival of isolated populations in the long term (Cornelisse, 2010).
The extirpation of P. meconis from Utah is largely tied to the destruction and fragmentation of dwarf bear-poppy habitat in and around St George, Utah. This area was and is a rapidly growing urban area with increasing human population; some projections estimate the population of Washington County will increase 243% between 2010 and 2050 (Utah Foundation, 2014). A 2016 report evaluating the conservation status of the dwarf bear-poppy found that around 50% of the plant’s historic habitat has been lost to urbanization and degradation from off-road vehicles, representing about 326 acres lost to development around St. George since the 1990s (USFWS, 2016). Unfortunately, even though remaining populations of the dwarf bear-poppy have been protected, most are still relatively isolated as a result of adjacent development and human activity. This isolation makes recolonisation for P. meconis, which is a small and weak-flying species, rather unlikely (Portman et al., 2019). The majority of the bee’s remaining habitat in Nevada is also under threat from development, located near Las Vegas and in Clark County, which had the second largest county population growth in the country in 2017 (Cornelisse, 2018).
Additional threats to the bees include livestock grazing, which both destroys host plants and disturbs soils; recreation, particularly OHV use that reduce the abundance of high quality ground nesting sites; and gypsum mining that destroys the soils in which the bear-poppies grow (Cornelisse, 2018; Irvin, 2025). Declines in P. meconis have also been associated with the introduction of the Africanized Honey Bee (AHB), which is a competitive pollen foraging species; increased competition with AHBs decreases the amount of pollen resources available to P. meconis, resulting in a need for longer foraging flights in order to provision pollen (Portman et al., 2018). Interestingly, the impacts of introduced AHBs on P. meconis seems to be exacerbated by grazing; as cattle preferentially graze on other floral resources, AHBs are pushed to visit dwarf bear-poppies at an increased rate, rapidly displacing the native pollinators of these flowers (Portman et al., 2019).
