Evidence from the latest research into two UK groups of scarce and threatened insects reveals that many of our leaf beetles and stoneflies are giving sufficient cause for conservation concern to be placed on a ‘red list’ of species that are under threat of local extinction.
The two new reports from the Species Status Project have been published by Natural England in collaboration with Buglife. They assess the conservation status of two groups of insects – leaf beetles (named after their habit of eating leaves) and stoneflies (aquatic species found in rivers and streams) – and classify them as either ‘vulnerable’, ‘endangered’ or ‘critically endangered’ .
The review of leaf beetles found that out of the 283 species in the UK:
· Three have become extinct in Britain in the last one hundred years
· Seven are classified as critically endangered and possibly already extinct in Britain, as they have not been seen since 1950
· 35 are placed on the new red list and considered either ‘critically endangered’, ‘endangered’ or ‘vulnerable’, and under threat of becoming extinct in Britain in the near future
Stoneflies fare slightly better. Out of 34 species found in Great Britain, one is now extinct, one is vulnerable to extinction, and another now joins the red list as a critically endangered species.
The two reports are the latest in a series to be published under the Species Status Project, which will help conservation organisations to target future action. The Species Status project is a new initiative that provides up-to-date assessments of the threat status of various species of insects using the internationally accepted guidelines developed by the International Union for Conservation of Nature (IUCN)
Both groups of insects are highly sensitive to their environment. Leaf beetles are often specific to certain plants in certain habitats. Stonefly larvae are particularly sensitive to organic pollution. They are regarded as excellent indicators of the natural environment and targeted action supported by both Natural England and the voluntary conservation sector is underway to try to prevent further declines in these species. The reports provide vital new evidence that will help focus resources on managing habitats in the best way to improve the conservation status of these overlooked but important insects.
The rare and visually stunning iridescent green tansy beetle (Chrysolina graminis) was once widespread in the Britain living in wetland areas, but it is currently critically endangered, not just in the UK but across its worldwide range. It is now a conservation priority species in England (section 41) species, which means that public bodies have a duty to protect it, together with its habitat. It was believed to have one last remaining stronghold in the UK on a 30km stretch of the banks of the river Ouse in York, mainly eating tansy (Tanacetum vulgare), a perennial herb which has given the beetle its name. At their York site they complete their entire life cycle on and around the plant, beside riverbanks or in wetlands. The site (Clifton Ings and Rawcliffe Meadows) was confirmed as a Site of Special Scientific Interest in May last year, and work is underway to improve its habitat and control the increase of invasive species such as Himalayan balsam which has resulted in a decline in tansy plants over the past few decades. This has of course affected tansy beetle numbers.
Recently another population of tansy beetle was discovered in in the East Anglian fens in July 2014 after a 40 year absence. The discovery at Woodwalton Fen National Nature Reserve (NNR) was significant as it demonstrates the resilience of the species when given the right conditions. Natural England has been working closely with partners on the Great Fen vision to create new habitat around the NNR, and with the Tansy Beetle Action Group (TBAG) to study how best to improve conditions for the beetle. Work underway also includes a recent re-introduction at Wicken Fen.
Hazel pot beetle
Pot beetles are a fascinating group of petal and leaf-eating beetles that get their name from the protective shell-like ‘pot’ that the larvae live in, created using their own droppings. A hazel pot beetle colony was found in Sherwood Forest in 2008. It was the first time the insect had been recorded in Sherwood Forest for 70 years. Management techniques underway include the nurturing of young birch as a food source.
Ten spotted pot beetle
The ten-spotted pot beetle occurs on wetland on protected sites. Whilst the beetle's numbers continue to be monitored, its future will be linked to the action plan for lowland raised bogs, its favoured habitat, and enhancing willow as a food source in its wetland home.
Jon Webb, Senior Entomologist at Natural England said: “These reviews further build on our knowledge of the status of these species, helping us to focus our attention on managing our protected sites appropriately to support those most in need”.
Steve Falk at Buglife said: “The recently published State of Nature Report showed that at least two out of three species of British wildlife are declining, and we know that many species of invertebrate have already become extinct in Britain. These reports will put a strong spotlight on those species that will become extinct over the next few decades unless we take positive action and try to reduce the many threats facing them.”
The reviews can be found on Natural England’s publications catalogue:
Stoneflies, or Plecoptera from the Greek, “pleated wing” are an ancient group of insects, dating from 250 million years ago, with 2,500 known species worldwide. Unsung inhabitants of the freshwater world, their larvae can grow to over 30mm in length, making them among the largest invertebrates found in fresh water. Due to their high oxygen requirements, the larvae are particularly sensitive to organic pollution.
Leaf beetles are important as ecological indicators due to the dependency of many species on complex factors such as vegetation structure. They are found in a much wider range of habitats then some other groups of insects such as butterflies, dragonflies and bumblebees. Monitoring their status and abundance can provide a very useful indication of ecological ‘health’ of the natural environment.