The role of Nyctelia circumundata (Coleoptera: Tenebrionidae) on litter fragmentation processes and soil fertility in Northeastern arid Patagonia

Abstract

Decomposition of organic matter and soil properties linked to carbon (C) and nitrogen (N) cycling are considered key processes in soil fertility. In arid ecosystems, most plant litter remains intact for long periods and is gradually consumed by macrodetritivore arthropods. Tenebrionid beetles (Coleoptera: Tenebrionidae) are the most abundant macrodetritivores in many arid environments worldwide, and it is widely suggested that these beetles are responsible for most of the nutrient cycling from accumulated litter in warm and dry seasons in these ecosystems. In this study, the role of Nyctelia circumundata Lesne (Coleoptera: Tenebrionidae) on soil fertility and litter fragmentation during the warm-dry season was experimentally evaluated in northeastern Patagonia, using microcosm experiments in the laboratory. Our results showed that the presence of litter alone is not enough to incorporate organic matter (OM), as well as nitrogen (N) or carbon (C) into the soil. Adult individuals of N. circumundata consumed a significant fraction of the litter offered in the experimental pots (~10 %) and this activity was also associated to increased soil N, C, and OM contents, and the C/N ratio. These facts highlighted that litter fragmentation, consumption, and its subsequent conversion into feces by N. circumundata positively affects soil fertility in northeastern Patagonia. Considering that tenebrionid beetles are a major group of primary consumers in deserts, these beetles play an important role in aboveground food web and a key energy conduit from plants (as litter) to higher trophic levels in this region. Finally, taking into account the ecological relevance of tenebrionid beetles for soil nutrient cycling (both at local and ecosytem scales) demonstrated in this work, we recommend incorporating these beetle assemblages into future conservation strategies for arid Patagonia.