The Threat to Insects

• Just under one million insect species have been identified on the planet and there are probably still more that have not yet been identified.
• However, 40% of them are under serious threat.
• Insects are characterised by having three pairs of legs and two pairs of wings – which are sometimes reduced or absent. They have three body segments: the head, thorax and abdomen. Some of them change their appearance during development in a process known as metamorphosis.
• Lepidoptera (moths & butterflies), Hymenoptera (comprising the sawflies, wasps, bees, and ants) and dung beetles (Coleoptera) are the taxa most affected.
• Four major aquatic taxa (Odonata, Plecoptera, Trichoptera and Ephemeroptera) have already lost a considerable proportion of species.
• Affected insect groups not only include specialists that occupy particular ecological niches, but also many common and generalist species.
• Concurrently, the abundance of a small number of species is increasing; these are all adaptable, generalist species that are occupying the vacant niches left by the ones declining.
• The main drivers of species declines appear to be in order of importance:
o habitat loss and conversion to intensive agriculture and urbanisation;
o pollution, mainly that by synthetic pesticides and fertilisers;
o biological factors, including pathogens and introduced species;
o climate change.
• A rethinking of current agricultural practices, in particular a serious reduction in pesticide usage and its substitution with more sustainable, ecologically-based practices, is urgently needed to slow or reverse current trends.
• In addition, effective remediation technologies should be applied to clean polluted waters in both agricultural and urban environments.
• Apparently, if all the insects on the planet were put together they would weigh more than all the humans put together. It is estimated that total insect biomass is 300 times greater than total human biomass.
• Insects also form a vital part of the food chain. Without them, there would be no birds, or any other animals that rely on insects as food.
• Even more sobering is the fact that the world would be littered with decomposing organic material. The consequence would be complete degradation of our soils. All remaining life would subsequently disappear.

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