Loss of insect species

The media has made much of a recent meta analysis, Worldwide decline of the entomofauna: A review of its drivers, published in the journal Biological Conservation. Researchers Francisco Sanchez-Bayo and Kris A.G. Wykhuys  have come to conclusions so frightening that even the newspapers couldn’t find the words to make it scarier than it really is.

The analysis has found that up to 40% of insect species could be lost within decades. In terrestrial ecosystems, the species in most danger are Lepidoptera, including butterflies and moths. In UK aquatic ecosystems it appears to be the caddis flies that are most at risk followed by dragonflies and damsel flies, stone flies and mayflies. These are insects that spend the largest part of their life in water on the beds of streams, rivers and ponds and have short aerial adult lives, sometimes no more than a few days.

Already many of these species are believed to be extinct. The main driver of these extinctions appears to be habitat loss to intensive agriculture and urbanisation.

Let’s put it into a local context: as Trowbridge creeps out into the greenfield sites that separate it from Southwick, it threatens the Lambrok Stream. Any change to the water quality of the stream or to the stream bed will change its ecosystem; the run off from a building site will, for instance, choke the stream bed with silt. The larvae of the stone flies and caddis flies which live on the stony bottom will die and there will be many fewer adults that year; the bats, among them the very rare Bechstein’s, that come to the park to feed on its flying insects will go and hunt elsewhere; so will hobbies, flycatchers, wagtails and dragonflies.

The fish that feed on the larvae of flying insects will leave; our kingfishers and the visiting heron will follow. The park’s whole ecosystem will be reduced.

These are dangerous times; we need to look after the things that are still here because it is uncertain how long we can survive without them.

Photographs: DKG and Creative Commons

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