ABSTRACT
This chapter summarises factors that permit rapid and dramatic changes in abundance, including responses to anthropogenic changes, and the utility of various insect groups as indicators of environmental changes. The decline or disappearance of indicator species or groups can provide early warning of deteriorating conditions and threats to ecosystem services, thereby serving as the canary in the mine. A variety of insects have proven to be useful indicators of environmental conditions. Insects have proven to be useful indicators of changes in terrestrial conditions, as well. Insect sensitivity to temperature change has provided some of the best evidence for global warming. Agricultural pests are benefitting from climate change for several reasons, and they pose serious threats to agriculture and forestry. Population sizes of insects fluctuate in response to variation in environmental conditions. Advance warning of the effects of environmental changes for people food supply and health requires monitoring of insect populations and anticipation of population growth or spread.
