Trophic structure and natural history of bat guano invertebrate communities, with special reference to Brazilian caves
The trophic structure and natural history of bat guano invertebrate communities in Brazilian caves was compared with information concerning bat guano communities in other caves throughout the world. The basis of Brazilian cave guano food webs are detritivorous organisms that directly consume guano, and microorganisms that live off deposits. These include mites, the most common organisms on guano, and others such as springtails (Acherontides eleonorae Palacios-Vargas & Gnaspini-Netto 1992), booklice (e.g. Psyllipsocidae), beetles (e.g. Dermestidae, Cholevidae), moths (e.g. Tineidae) and flies (e.g. Phoridae, Milichiidae). Facultative detritivores are also common, forming large populations when other organic substrata, such as vegetable debris, become scarce, as in the case of permanently dry caves. These are isopods (e.g. Trichorrhina sp.), diplopods (e.g. Pseudonannolene sp.), cockroaches, crickets (e.g. Endecous sp.), and silverfish (e.g. Coletinia brasiliensis Mendes & Ferreira in press). Other detritivores, like flatworms, earthworms, gastropods and harvestmen, are rarely found. Detrivores are in turn consumed by a wide range of predators, like pseudoscorpions (e.g. Chernetidae), spiders (e.g. Loxosceles similis Moenkhaus 1898, Oecobius annulipes Lucas 1846), and heteropterans (Reduviidae Zelurus variegatus Costa-Lima 1940). Facultative predators, like scorpions and whip-scorpions attracted by prey items, are also occasionally abundant. Food webs of bat guano communities in Brazilian caves are richer in species than those elsewhere.