page_title: Drosophila nigrospiracula
section_title: Habitat
hierarchical_section_title: Drosophila nigrospiracula / Habitat
caption_attribution_description: English: Carnegiea gigantea or Sahuaro or Saguaro, in the Sonoran desert
context_page_description: Drosophila nigrospiracula is a fly species indigenous to the Sonoran Desert, spanning Arizona, California, and part of Sonora, Mexico. D. nigrospiracula share the Sonoran Desert with three other species of Drosophila: D. pachea, D. mettleri, and D. mojavensis. D. nigrospiracula do not exhibit sexual isolation between the other species. This fly breeds on the decomposing tissues of two species of cacti that are also endemic to the region: cardón and saguaro.
context_section_description: D. nigrospiracula are only found in the Sonoran Desert and specifically on cardón (Pachycereus pringlei) and saguaro (Carnegiea gigantean) cacti. Cardón and saguaro are tall, columnar cacti with similar morphology, chemical composition, and low alkaloid composition (their main allelochemical). Saguaro grow on the main part of the desert, while the cardón species grows only on the Baja peninsula. D. nigrospiracula is restricted to these two forms of cacti because they emit the alkaloids gigantine and carnegine, which D. nigrospiracula can metabolize. These allelochemicals are usually harmful to an insect without the proper allelochemical detoxification enzymes – namely the cytochrome p450 system. In general, formation of plant decay can come from injury or freezing of the cactus.  Then, exudate flows down the plant, creating a place for D. nigrospiracula to congregate.
caption: A saguaro cactus (Carnegiea gigantea) found in the Sonoran Desert.
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