Reversing Insect Declines

Insects are in decline in the UK. Their numbers and range are dwindling and have been since at least the 1970s [1]. Many insects are not well studied, and information on all insects is centred around a few groups, such as bees and butterflies. These species have been well-researched due to their importance as pollinators, their vibrant colours, and their unique social behaviours. Insects are also challenging to conserve because they have complex life-cycles. For example, dragonflies need freshwater for the larval part of their life-cycle. The threats that insects face include climate change, habitat fragmentation and intensification of agriculture.

The Wildlife Trusts have recently published a report titled “Reversing the Decline of Insects” which sets out what we can do to support the recovery of insects in the UK. This article will investigate how we can replenish insect habitat, as well as how you can get involved in monitoring insects near you.

Hay Meadow Habitats

Revitalising our hay meadows is essential for enabling an insect comeback. Meadow flowers bloom all through summer and can provide an integral food source for bees, butterflies and other critters. However, modern hay fields don’t include the same diversity as they used to and are increasingly becoming grass monocultures. They are harvested earlier in the year so any flowers that were present die before they are able to disperse their seeds [2]. Wildflowers are no longer allowed to thrive in these areas, cutting off the nectar food supply that many insects, such as butterflies, rely on to survive [3].

“Traditional meadow grasslands were cut in late summer, when farmers used to harvest their hay. A lot of our meadows are adapted to that cycle and cutting earlier gets rid of flowers and prevents things from setting seed.”

Steve Garland, Chair of Lancashire Wildlife Trust

Studies show that mowing later in the year and leaving unmown refuge areas can benefit pollinator populations [4]. Later mowing allows flowers to continue providing nectar late into the summer, which is especially important for insects that hibernate like bees [5]. Meadows are hyper-diverse and can have as many as 40 species per square metre [6]. They have the potential to provide a foundation for nationwide insect resurgence if correctly managed.

Wildflower hay meadow in the Yorkshire Dales National Park
Image Credit: Colin Gregory (CC BY-SA 2.0)

B-Line Habitat Connections

Well managed grasslands and meadows are an integral part of the landscape for insect survival, however these patches of habitat don’t allow insects to traverse long distances across the country. Both the amount and connectivity of the habitats are vital for sustaining insect populations [7]. Fragmentation of the habitat into small islands within the landscape makes the resident insect population vulnerable to events like drought or flooding [8]. There may not be another suitable habitat for miles which makes recovery almost impossible.

“The key word is ‘network’. Up until now we have had nature reserves which are very good but separated from each other. In some places it has become very hard for insects to travel to the next suitable place. We need to connect existing hotspots together so wildlife can move around.”

Steve Garland, Chair of Lancashire Wildlife Trust

The B-lines project from BugLife UK aims to plant an interconnected web of 150,000 hectares of flower-rich habitat across the UK, enabling bees and other invertebrates’ safe avenues through the countryside [9]. BugLife UK have an interactive map of the B-lines with all their wildflower projects on it. You can get involved by planting bee-friendly flowers such as lavender in your garden or by supporting other local community projects nearby.

A wildflower verge in Cot Valley
Image Credit: Rod Allday (CC BY-SA 2.0)

“With climate change it is becoming more import to connect insect hotspots together as wildlife need to travel in response to rising temperatures.”

Steve Garland, Chair of Lancashire Wildlife Trust

Insect Monitoring Schemes

Insect monitoring schemes are vital to conservation efforts. The more people who get involved watching for wildlife in their garden, the more information scientists and policy makers have to inform their decisions about countryside management.

Comma butterfly (Polygonia c-album) in Wheatfen nature reserve
Image Credit: Evelyn Simak (CC BY-SA 2.0)

The Big Butterfly Count is a scheme run between the 17th of July and the 9th of August by the Butterfly Conservation to monitor the range and numbers of butterflies in the UK. Everyone can get involved by downloading their free butterfly ID sheet here and sitting in the sun for 15 minutes, counting which butterflies visit. The observations are then used to ‘take nature’s pulse’ and evaluate any changes in specific regions to identify drivers. Your counts could be used to find and implement new solutions to bolstering butterfly numbers! More information can be found on their website here. If you want to record species of other insects that visit your local garden or park, use a good ID guide and the iRecord App to submit your findings.

The next post will explore urban gardens as hubs for enjoyment, wildlife and food production. In a time of growing urbanisation, how can we ensure that our gardens provide safe havens for humans, plants and animals?

Thank you very much to Steve Garland from the Lancashire Wildlife Trust for agreeing to be interviewed about the “Reversing the Decline of Insects” report and for giving such open and engaging answers! I thoroughly recommend giving the report a read as it goes into a lot of detail on a wide range of strategies to encourage insects in the UK.

References

[1] Dirzo, R. et al. (2014) ‘Defaunation in the Anthropocene’, Science. American Association for the Advancement of Science, pp. 401–406. doi: 10.1126/science.1251817.
[2] Tallowin JRB, Smith REN, Goodyear J, Vickery JA (2005) Spatial and structural uniformity of lowland agricultural grassland in England: a context for low biodiversity. Grass Forage Sci 60: 225–236.
[3] LEBEAU, J., WESSELINGH, R.A. and VAN DYCK, H., 2015. Butterfly Density and Behaviour in Uncut Hay Meadow Strips: Behavioural Ecological Consequences of an Agri-Environmental Scheme. PloS one, 10(8), pp. 1.
[4] BURI, P., HUMBERT, J. and ARLETTAZ, R., 2014. Promoting pollinating insects in intensive agricultural matrices: field-scale experimental manipulation of hay-meadow mowing regimes and its effects on bees. PloS one, 9(1), pp. 1.
[5] https://www.bumblebeeconservation.org/how-do-bumblebees-hibernate/
[6] http://www.bbc.co.uk/earth/story/20150702-why-meadows-are-worth-saving
[7] Bosco, L., Wan, H.Y., Cushman, S.A. et al. Separating the effects of habitat amount and fragmentation on invertebrate abundance using a multi-scale framework. Landscape Ecol 34, 105–117 (2019). https://doi.org/10.1007/s10980-018-0748-3
[8] Stoll, C. Dolt, M. Goverde, B. Baur, 2006, Experimental habitat fragmentation and invertebrate grazing in a herbaceous grassland species. Basic Appl. Ecol., 7 (2006), pp. 307-319
[9] https://www.buglife.org.uk/our-work/b-lines/