Potential adverse effects of volcanic ash from Puyehue- Cordón Caulle Range on tenebrionid larvae

LOPEZ GARCIA GUILLERMO; BUTELER, MICAELA; STADLER, T.

Mendoza

Simposio; Fourth International Tenebrionoidea Symposium; 2015

Sociedad Internacional Tenbrionidae

The Puyehue Cordon Caulle (PCC) volcanic outbreak from 2011 affected most of thesurface of the Monte Austral region in the Argentine Patagonia. This area is rich inendemic species and Tenebrionidae is well represented, playing a key role byinterlocking in the ecosystem food web. The insecticidal effect of volcanic ash (VA) hasbeen proven to occur by contact exposure, disturbing the water balance in insects.Tenebrionid larvae are somewhat protected from massive exposure to VA fall due totheir cryptic habits. However, particles from VA deposits move progressively into theunderlying soil and tenebrionid larvae may become exposed to VA contaminated food.The aim of the study was gain further understanding of the impact of volcanism on foodchain processes and nutrient cycling in the Monte Austral. For this purpose, we studiedthe intake toxicity of VA on tenebrionid larvae in laboratory bioassays, fed on flourdiscs prepared with VA at 500, 1,000; 5,000; 30,000 and 50,000 ppm. Tenebrio molitorwas used as an experimental model organism, given that it develops in conditionsanalogous to those of many other tenebrionid euryphagous species from xerophilichabitats, mostly associated with the soil. It was found that intake toxicity of VA in T.molitor larvae was dose-dependent with effects visible after long term exposure.Mortality was observed at the two highest concentrations tested and at the lowerconcentrations, sub-lethal effects as larval size lessening, weight loss and reduction inthe number of molts were registered. It can therefore be concluded that intake toxicity isa major adverse effect of VA on tenebrionid larvae that would lead to massive mortalityat high concentrations and dwarfing effects at sub-lethal concentrations. Thus, theintake of VA by larvae may have harmful effects on tenebrionid natural populations andconsequently on the Monte Austral ecosystem.