Unusual nesting habits, floral associations, and natural enemies of the Neotropical leaf-cutter bee Megachile exaltata Smith (Hymenoptera: Megachilidae)
DOI:
https://doi.org/10.17161/jom.vi138.24800Abstract
Leaf-cutter bees (genus Megachile Latreille) represent a diverse group whose biology remains poorly documented, especially in the tropics. Here, we describe the nesting behavior, cell morphology, floral associations, and natural enemies of Megachile (Austromegachile) exaltata Smith, based on nests found in Western Costa Rica. Brood cells were built entirely from leaf pieces of Euphorbia (Chamaesyce) (Euphorbiaceae), and many were built in the open, rather than within pre-existing cavities. These exposed cells were placed among a wide range of man-made objects, such as umbrellas, plastic panels, black plastic bags, and even clothing. Bees also nested in pre-existing cavities, such as crevices, bamboo canes, and abandoned nests of black mud dauber wasps (Sphecidae: Sceliphron spp.). Palynological analyses of brood provisions showed that pollen consisted exclusively of Muntingia calabura L. (Muntingiaceae), a widely distributed Neotropical shrub or tree, indicating monofloral foraging. Brood cells were parasitized by the cuckoo bee Coelioxys otomita Cresson, parasitic wasps (Chalcididae: Brachymeria sp.), and phorid flies [Phoridae: Megaselia scalaris (Loew)]. These findings expand our understanding of the nesting plasticity and ecological interactions of Neotropical leaf cutter bees.
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