Centris pallida

Fox, 1899

Pallid Desert-Digger, digger bee, desert bee, pallid bee

Centris pallida is a solitary desert to the Sonoran Desert region of North America. Males exhibit two distinct associated with alternative reproductive tactics: large patrollers that use olfactory cues to locate buried virgin females near the ground, and small hoverers that use visual cues to find females above vegetation. The has evolved remarkable thermal to survive extreme desert temperatures, including high thoracic conductance and solar reflectance in large-morph males. Long-term studies document a persistent decline in male body size since the 1970s, with potential consequences for the of alternative reproductive tactics.

Centris pallida distribution map by Floyd Burney. Used under a CC BY-SA 4.0 license.

Pronunciation

How to pronounce Centris pallida: /ˈsɛntrɪs ˈpælɪdə/

These audio files are automatically generated. While they are not always 100% accurate, they are a good starting point.

Identification

Males and females are approximately 16–17 mm in length. The surface is black with dense grey ; fur has a slight tint in males, more in females. Legs have mixed black and reddish fur. surface has brownish to dark yellow fur. are transparent with black . Males have yellow and lighter thorax fur; females have green eyes and darker thorax fur. Males are : large have paler dorsal coloration, small morphs have dark brown dorsal coloration.

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Habitat

Dry, hot desert environments of the Sonoran Desert. During daytime, individuals hide in or in burrows to prevent overheating. At night, they shelter under rocks, in trees, or in burrows to survive cold desert nights.

Distribution

Southwestern United States (Arizona, Nevada, southern California, New Mexico) and western Mexico.

Seasonality

emerge from late April through early May. Adults live approximately one month; by late July, virtually no individuals remain active.

Diet

feed on nectar from flowers adapted to hot desert conditions, primarily palo verde (Cercidium microphyllum, C. floridum), ironwood (Olneya tesota), and creosote bush (Larrea divaricata). Palo verde pollen is the primary provision, giving a strong orange color. Males consume approximately 3.5 times their body weight in nectar daily due to high energy expenditure during mate location behaviors.

Life Cycle

Females dig diagonal tunnels approximately 30 cm deep, terminating in a 2.5 cm vertical chamber 20 cm below the surface. Each chamber contains a pot lined with , filled with nectar and pollen of molasses-like consistency. The is laid on top of the and sealed with wax; the tunnel is partially filled with dirt for protection. Eggs hatch within two weeks; consume provisions and develop into . Prepupae undergo over eleven months. dig to the surface in late April or early May. Females can construct multiple burrows during their lifetime.

Behavior

Males use alternative reproductive tactics: patrollers 3–6 cm above ground searching for sites of buried virgin females, digging 1–2 cm through soil when a site is located; hoverers wait near vegetation or flowering plants away from emergence areas, flying 3 cm to 8 m above ground. Patrollers show little territoriality due to large search areas; hoverers defend territories approximately 1 m in diameter, abandoning and relocating frequently. Males detect female emergence with highly olfaction, digging up and even other . Females mate once. During daytime heat, individuals are inactive, hiding in or burrows.

Ecological Role

of desert plants including cacti, desert willow, and palo verde. Tunneling activity aerates soil, facilitating rainwater penetration to roots. Nitrogen-rich fertilize soil.

Human Relevance

are mild and not dangerous to humans. Burrowing by dense female can create unsightly soil mounds. Studied as a model system for alternative reproductive tactics, thermal physiology, and climate change impacts on body size and behavioral .

Similar Taxa

  • Centris cockerelliSame and overlapping desert , but differs in mating system, coloration, and subgenus
  • Habropoda pallidaShares '' and similar desert burrowing , but belongs to different (: Anthophorinae); distinguished by lack of male and different thermal

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Sources and further reading