Hawaiian Yellow-faced bee (Hylaeus mana)
Where Listed: WHEREVER FOUND
Hylaeus mana is similar in structure to other hymenopterans (bees, wasps, and ants) in that adults have three main body parts-a head, thorax, and abdomen. One pair of antennae arises from the front of the head, between the eyes. Two pairs of wings and three pairs of legs are attached to the thorax. The abdomen is composed of multiple segments (Borror et al. 1989, pp. 665-666). The Hylaeus genus, which includes Hylaeus mana, are commonly known as yellow-faced bees or masked bees for their yellow-to-white facial markings. All of the Hylaeus species roughly resemble small wasps in appearance, due to their slender bodies and their seeming lack of setae (sensory hairs). However, Hylaeus bees have plumose (branched) hairs on the body that are longest on the sides of the thorax. To a discerning eye, it is these plumose setae that readily distinguish them from wasps (Michener 2000, p. 55). This species is an extremely small, gracile (gracefully slender) black bee with yellow markings on the face. The smallest of all Hawaiian Hylaeus species, H. mana is a member of the Dumetorum species group. The face of the male is largely yellow below the antennae, extending dorsally in a narrowing stripe. The female's face has three yellow lines, one against each eye, and a transverse stripe at the apex of the clypeus (lower face region). The female’s other markings are the same as the male’s (Daly and Magnacca 2003, p. 135). Hylaeus mana can be distinguished from H. mimicus and H. specularis, species with overlapping ranges, by its extremely small size, the shape of the male’s genitalia, the female’s extensive facial marks, and a transverse rather than longitudinal clypeal marking (Daly and Magnacca 2003, p. 138).
- States/US Territories in which the Hawaiian Yellow-faced bee, Wherever found is known to or is believed to occur: Hawaii
- US Counties in which the Hawaiian Yellow-faced bee, Wherever found is known to or is believed to occur: View All
- Countries in which the the Hawaiian Yellow-faced bee, Wherever found is known to occur: United States
|Status||Date Listed||Lead Region||Where Listed|
|2016-10-31||Pacific Region (Region 1)||Wherever found|
» Federal Register Documents
No recovery information is available for the Hawaiian Yellow-faced bee.
» Critical Habitat
No critical habitat rules have been published for the Hawaiian Yellow-faced bee.
» Conservation Plans
No conservation plans have been created for Hawaiian Yellow-faced bee.
» Life History
). Likewise, the exact nesting habits of H. mana are not known, but the species is thought to nest within the stems of mesic shrub species (Magnacca and Danforth 2006, p. 403). Sahli et al. (2008, p. 1) quantified pollinator visitation rates to all of the flowering plant species in communities on a Hawaiian lava flow dating from 1855 to understand how pollination webs and the integration of native and nonnative species changes with elevation. In that study, eight flowering plants were observed at six sites, which ranged in elevation from approximately 2,900 to 7,900 feet (ft) (approximately 880 to 2,400 meters (m)). The study also found the proportion of native pollinators changed along the elevation gradient; at least 40 to 50 percent of visits were from nonnative pollinators at low elevation, as opposed to 4 to 20 percent of visits by nonnative pollinators at mid to high elevations. Hylaeus bees were less abundant at lower elevations, and there were lower visitation rates of any pollinators to native plants at lower elevations, which suggest Hylaeus may not be easily replaceable by nonnative pollinators (Sahli et al. 2008, p. 1).
The exact diet of the larval stage of Hylaeus mana is unknown, although the larvae are presumed to feed on stores of pollen and nectar collected and deposited in the nest by the adult female (Daly and Magnacca 2003, p. 9). Likewise, the exact nesting habits of H. mana are not known, but the species is thought to nest within the stems of mesic shrub species (Magnacca and Danforth 2006, p. 403). Adult specimens of Hylaeus mana were collected while they visited flowers of Santalum freycinetianum var. freycinetianum (iliahi, sandalwood), a native Hawaiian plant found only on Oahu and Molokai (Wagner et al. 1999, p. 1,221). It is likely H. mana visits several other native plant species, including Acacia koa, Metrosideros polymorpha, Styphelia tameiameiae, Scaevola spp., and Chamaesyce spp. (Magnacca 2005g, p. 2). Hylaeus mana, like most Hylaeus species, lack an external structure for carrying pollen, called a scopa, and instead internally transport collected pollen, often mixed with nectar, within their crop (stomach). Recent studies of visitation records of Hawaiian Hylaeus bees, to native flowers (Daly and Magnacca 2003, p. 11) and pollination studies of native plants (Sakai et al. 1995, pp. 2,524–2,528; Cox and Elmqvist 2000, p. 1,238; Sahli et al. 2008, p. 1) have demonstrated Hawaiian Hylaeus species almost exclusively visit native plants to collect nectar and pollen, pollinating those plants in the process. Hylaeus bees are very rarely found visiting nonnative plants for nectar and pollen (Magnacca 2007a, pp. 186, 188), and are almost completely absent from habitats dominated by nonnative plant species (Daly and Magnacca 2003, p. 11).
Movement / Home Range
Historical Range/Distribution: Hylaeus mana is only known from lowland mesic forest located along the Manana Trail in the Koolau Mountains on Oahu, at an elevation of about 1,400 ft (430 m). Few Hylaeus bees have been found in this type of Acacia koa-dominated, lowland mesic forest on Oahu (Daly and Magnacca 2003, p. 138). This type of forest is increasingly rare and patchily distributed on Oahu (Smith 1985, pp. 227–233; Juvik and Juvik 1998, p. 124; Wagner et al. 1999, pp. 66–67, 75). The Manana Trail is part of the Na Ala Hele Hawaii Statewide Trail and Access System (DLNR 2007), and is located within the State’s Ewa Forest Reserve (FR). Six miles in length, the beginning of the Manana Trail is dominated by nonnative plant species, but leads into an area of native forest where Acacia koa, Metrosideros polymorpha, and Scaevola spp. are common (DLNR 2011 - http://hawaiitrails.ehawaii.gov/trail.php?TrailID=OA+09+008). Current Range/Distribution: Because the first collection of Hylaeus mana was made in 2002, its historical range and current distribution, other than the collection on Manana Trail, are unknown at this time (Magnacca 2005g, p. 2). Additional surveys in potentially suitable habitat may reveal additional populations elsewhere on Oahu (Magnacca 2007a, p. 184). However, the extreme rarity of this species, its absence from nearby sites, and the fact it was not discovered until very recently, suggests very few populations remain (Magnacca 2005g, p. 2).
The general life cycle of Hylaeus mana is typical of most solitary bees: after mating, females create a nest in which to lay eggs that will hatch and develop into larvae (immature stage); as larvae grow, they molt (shed their skin) through three successive stages (instars); when fully grown the larvae change into pupae (a resting form) in which they metamorphose and emerge as adults (Borror et al. 1989, p. 665). Hawaiian Hylaeus species are grouped within two categories: ground-nesting species that require relatively dry conditions, and stem-nesting species that are often found within wetter areas (Zimmerman 1972, p. 533; Daly and Magnacca 2003, p. 11). Hylaeus mana is believed to be a stem-nesting species (Magnacca 2005g, p. 2; Magnacca and Danforth 2006, p. 403), and the species likely constructs nests opportunistically within existing burrows inside dead twigs or plant stems. This is unlike the nest construction of many other bee species, which are purposefully excavated or constructed underground. All Hylaeus spp., including the Hawaiian Hylaeus species, lack strong mandibles and other adaptations for digging and often use nest burrows abandoned by other insect species (Daly and Magnacca 2003, p. 9). Hylaeus mana females lay eggs in brood cells she constructs in the nest and lines with a self-secreted, cellophane-like material. Prior to sealing the nest, the female provides her young with a mass of semiliquid nectar and pollen left alongside her eggs. Upon hatching, the grub-like larvae eat the provisions left for them, grow and molt through three instar stages, pupate, and eventually emerge as adults (Michener 2000, p. 24).
Population Estimates/Status: Hylaeus mana is currently known from a single population within lowland mesic forest habitat (Magnacca 2005a, p. 2) on the island of Oahu. The size of this population is unknown. Table 1, below, summarizes information about the current population sites for this species. Table 1. Occupied population sites and habitat conservation status of Hylaeus mana on the island of Oahu. Population Site Island Land Owner Last Year Observed (or survey) Approx. Size in Acres Habitat Conservation Status & Threats 1 Manana Trail (Ewa Forest Reserve) Oahu State 2002 Unknown Some conservation
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