A rare flightless beetle found in only two locations in the UK has been counted in abundance on the Isle of Coll.
RSPB Scotland and Buglife researchers visiting the island were surprised to discover over 150 Short-necked oil beetles (Meloe brevicollis) on survey sites, a 400% increase on the last count carried out in 2010. Teams also identified two new sites for the beetle on the island.
Until 2006, Short-necked oil beetles were thought to be extinct in the UK. However, recent surveys determined there are two small populations present- one in Devon and the other on Coll, which was found later in 2009.
The beetle, which is named for the toxic oil secretions it produces when threatened, has an interesting lifecycle. It emerges in the early spring and immediately begin feeding on a wide variety of vegetation. After feeding on buttercups and other low growing plants, the beetles mate and the females begin the process of digging a burrow and laying over 1000 tiny orange eggs which hatch in a few weeks.
Once the eggs have hatched, the young larvae (called triungulins) crawl up on to vegetation, and wait to hitch a lift on a passing solitary bee in order to reach the bee’s nest. The oil beetle larvae then eat the bee’s egg as well as the protein- rich pollen the bee provides to its own larvae, emerging as a fully formed beetle the following spring.
It is thought changes in farming practices across the UK have led to short-necked oil beetle declines. The intensification of agriculture and the loss of flower-rich meadows have been linked to a decline in bee populations- which have a knock-on effect on beetle populations.
James Silvey, Nature Recovery Officer at RSPB Scotland, said: “It is fantastic to discover so many individual beetles on Coll and a good sign that the population is healthy and continuing to grow. The wildflower-rich habitat and the extensive dune systems found on this island make a fantastic home for bees and beetles alike. We will continue to monitor this population but it seems clear from this survey that Coll is the best place in the UK for this incredible species.”
Dr Scott Shanks, Conservation Officer at Buglife Scotland, said: “It was really exciting to find so many of these charismatic and rare beetles on Coll during the surveys. The abundance of wildflowers in the machair and dunes of the island, combined with lots of warm, bare sand provide near-perfect habitat for the solitary bees that the oil beetles depend on. It is hoped that the Information collected during the surveys will help protect these rare beetles and help identify other sites where the beetles may be found.”
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