**1. Introduction**

Insects are the most diverse and abundant group of animals on Earth and are critical drivers of ecosystem function in terrestrial and aquatic systems.

Biodiversity of insects is threatened worldwide [1]; 40% of the world's insect species could go extinct within decades [2] with consequent loss of ecosystem functions and services.

Despite the attention from the media, and scientific community, it remains unclear whether such declines are widespread among habitats and geographic regions. Since most of the insects are providing services (e.g., pollination and decomposition) and disservices (e.g., damaging crops and spreading diseases), the efforts in insect conservation biology and population management have been mainly conveyed to highly impacted areas like, for instance, the lowlands.

On the other hand, around the world, mountain regions are changing at an unprecedented rate. Most of the evidences are based on the abiotic component (e.g., temperature increase and precipitation variations), but there are increasing evidences about changes in biological communities.

At high altitude in tropical and temperate mountains and at high latitude, habitat loss, pollution and climate change affect negatively cold-adapted insect species distribution and survival [3, 4]. It is unlikely that insect declines will be homogenous everywhere, but some general patterns can be identified. For example, at high altitude, the high frequency of extreme climatic events and the loss of ice-related

landforms (e.g., glaciers and rock glaciers) are detrimental to cold-adapted insects, highly specialized to survive constantly at low temperature, high humidity, deep snow and ice cover. Most of the glaciers are strongly reducing their surface, some are disappearing, others are shifting in debris-covered glaciers and permafrost is melting [5]. The effects of climate change on high-altitude terrestrial and aquatic insect community composition and ecosystem functioning are partially unknown and still underconsidered [6].

Scattered studies on high-altitude and high-latitude insect communities are available for most of the glacialized areas of the world, but a synthesis paper merging the most recent advances on cold-adapted insect species living on and at the edge of ice-related landforms is still not available. To fill this gap, the purpose of this chapter is to (i) describe what insects live in glacialized areas, (ii) examine what are the flagship insects in terms of richness and adaptation to cold, (iii) identify threats and opportunities in the current warm-period and (iv) illustrate the role of insect communities in the glacial-ecosystem functioning and services.
