Colletes merceti

Colletes merceti is a solitary mining bee belonging to the family Colletidae, a group commonly known as plasterer or cellophane bees for the smooth, cellophane-like secretion females use to line their underground nest cells. Like other members of the genus, this species is a ground-nesting insect, excavating narrow burrows in sandy or loose soils where females provision individual brood cells with pollen and nectar collected from regional flora. Colletes merceti is known from a highly restricted range, and its survival is closely tied to the availability of specific open-ground nesting sites and flowering plant communities that provide seasonal forage.

The species is currently classified as Critically Endangered (CR) by the IUCN, reflecting an extremely limited distribution, ongoing population decline, and heightened vulnerability to further habitat disturbance. Land conversion, changes in land management practices, and degradation of natural open habitats have reduced the availability of suitable nesting substrate and forage plants, placing sustained pressure on remaining populations. As with many narrow-range solitary bees, small population size and fragmented habitat increase susceptibility to local extinction events, and the species' decreasing population trend underscores the urgency of targeted conservation attention.

Encouragingly, growing scientific interest in wild bee conservation across its native range has led to increased survey efforts aimed at better defining the species' distribution and habitat requirements, a critical first step toward effective protection. Regional pollinator conservation initiatives are also beginning to incorporate habitat management practices, such as preserving bare-ground nesting areas and native flowering plant diversity, that may benefit Colletes merceti alongside other threatened solitary bees. Continued monitoring and habitat safeguarding will be essential to prevent further decline of this Critically Endangered species.

This specialized solitary bee inhabits sandy coastal areas and Mediterranean shorelines, where it excavates nesting burrows in loose, well-drained sandy soils. The species requires specific microhabitat conditions found in undisturbed coastal dunes and sandy beaches with appropriate flowering plants for foraging.