The role of tenebrionid beetles on litter fragmentation processes and soil biogeochemical cycles in arid Patagonia

Abstract

Tenebrionid beetles are among the most abundant and diverse insects of arid environments. They are considered mostly detritivores and given their multiple physiological and behavioral adaptations, they might play an important role on biogeochemical cycles in these environments. However, in South America, there are few or no studies that has directly quantified or demonstrated this role. South America endemic species of the Nycteliini tribe (subfamily Pimelinae) are specially adapted to arid and semi-arid environments. Within this tribe, the genus Nyctelia dominates the fauna of Tenebrionidae in Patagonian steppes, being Nyctelia dorsata (Fairmaire) one of the main components of the epigean insect community of northeast of Patagonia. Due to their apterous condition N. dorsata distribution is restricted and It is frequently observed feeding on litter. The objective of this work was to evaluate the detritivore role of N. dorsata and its effect on soil N cycle throughout microcosms experiment. Collected Tenebrionids were fasted for 7 days before the experiment starts. Microcosms were subjected for 26 days to the following treatments: Soil with no litter (S); Soil + litter of one of the most important plant species on its diet (Lycium chilense) (SL) and Soil + litter (Lycium chilense) + N. dorsata (SLN). At the end of the experiment, litter mass loss and total soil N concentration were analyzed by GLM. Litter mass loss was significantly higher at SLN than at SL. Total soil N was higher at SLC than at SL and S while we found no differences between S and SL. We concluded that in Patagonian arid environments N. dorsata plays a key role in biological fragmentation processes of plant residues and soil biogeochemical cycles. Moreover, this role is particularly important in dry season, when soil microbial activity is reduced due to the harsh environmental conditions.