Volcanic complex Puyehue-Cordón Caulle: impact of volcanic ash on insects in Patagonia, Argentina

FERNÁNDEZ ARHEX, V; PIETRANTUONO, A.L; AMADIO, E.; BRUZZONE, O

Volcanic Eruptions: Triggers, Role of Climate Change and Environmental Effects-

Nova Science Publishers

Año: 2014; p. 141 - 158

In June 4 2011, there was a major volcanic eruption of the Puyehue-Caulle complex (PCC) in southern Andean range near the Argentina-Chile border. This event covered with ashes over 7.5 million hectares in Argentinean Patagonia during for a year and affecting the flora and fauna, including the insect. On this chapter we present different case studies which evaluated the effect of volcanic ash on survival, motivation and use of habitat in different species of insects. Laboratory bioassays results have shown that the ash does not affect the species studied in the same way, and also there are differences between guilds of phytophagous insects. Phloem-sucking insects are not strongly affected, actively choose their habitats for living and are capable of discriminate unfavorable habitats (i.e. presence of volcanic ash). On the other hand on orthopteran species, the volcanic ash has a strong aversive and insecticidal effect similar to that of inert dust. In this case the volcanic ash could potentially have a protective effect against insect pests, reducing the damage they can cause to grasslands and pastures. The impact of the ashes from PCC on the insect community may be radical in the acute deposition phase, with substantial qualitative effects in the chronic phase of exposure. The recovery of populations affected by ash in desert areas where dry ash persists will be slower, and this will have tangible and long-term consequences for insect host plants, and on the development of populations of vertebrate insectivores. By contrast, the presence of ash in humid regions will impact the ecosystem by the addition of nutrients, which in combination with water retention by the ash will lead to a qualitative and quantitative recovery of the populations under favorable conditions. Therefore we propose establish that the ash can generate two types of responses on insects: direct (on individuals) or indirect (on individual-environment interactions).