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Green Fingers

Nurturing insects

Week 49


I hope I have not done the wrong thing. I have been dithering for several weeks as to whether I should transplant some trees from one part of my land to another. I have been spending plenty of time thinking, rather than doing, but in the end decided transplantation should proceed. All went well, with a sycamore[i], mountain ash[ii] and holly[iii] being shifted from one spot to another. The sycamore and mountain ash have also been supported with stakes - the holly is too small - as Lakeland experiences plenty of high winds. Staking a tree is an important skill but there is a right and wrong way of staking.

Staked sycamore sapling in the snow
The snow has arrived - there is a sycamore under that lot

A stake should be positioned low down a young tree’s trunk, as the trunk grows partly in response to movement. Attaching a stake too high may certainly reduce movement but may lead to a weakened trunk that is unable to withstand the elements. The stake should also be positioned to resist the prevailing winds. For my land these are from the south-west, so I point stakes in that direction, fixing them from the north-eastern side of the tree. I avoid vertical stakes as they can damage the roots when being hammered into the earth.


Stakes should be removed as soon as possible, and certainly once the tree has become established. An average timeframe is 18-36 months. If I am in any doubt, I remove a tie at the end of a growing season and check for windrock. I can easily retie the stake to the tree if there is a problem[iv].


My young sycamore and mountain ash are now properly staked, and both feel and look supported. The problem? Frost followed by snow, I fear. This week has seen some very low temperatures, well below 0°Celsius, and the police have declared a major incident thanks to snow. Although my trees were dormant when transplanted - during dormancy is the best time to transplant - extreme cold can damage plant tissues and lead to die-back or tree death. The increase in stress may affect growth and make the trees more susceptible to disease[v]. If transplantation is performed when a tree is actively growing, that is the worst thing to do, as the tree is even more vulnerable to cold at that time. Right now, all I can do is hope.

Early shoots appearing through the soil
Next year's shoots are already appearing

I once thought that land and gardens were messy and inactive as the year’s end approached, yet somehow my land is still busy and there is plenty to do. I have pruned my deciduous ferns well back, near to ground level, while I have left my evergreen ferns[vi] alone. Immediately beside them I can already see next year’s plants emerging. Perhaps they are early snowdrops[vii] but I cannot be certain. It is evident that there is no such thing as rest for Nature. My land shows that perfectly. It was John Muir[viii] who said it:


Nature is ever at work building and pulling down, creating and destroying, keeping everything whirling and flowing, allowing no rest but in rhythmical motion, chasing everything in endless song out of one beautiful form into another.”


He was right.


One of the many reasons I began to renature was to increase the population of insects on my land. Insects are clearly struggling nationwide. For example, work from Kent found that the abundance of flying insects in the UK has plummeted by nearly 60% over the last 17 years[ix].


Meanwhile around me are so many other humans doing little or nothing to help. They mow lawns, use pesticides and herbicides, fell trees to make space, and replace grass with hardstanding. I find it remarkable that anyone still thinks this way, but it is clear they do. Wildlife is declining, at all levels, with birds especially finding it difficult, as there are fewer places to hide or nest. Raptors have all but vanished, although I suspect avian ‘flu may be partly to blame. Somehow, I must bring the birds back and encouraging insects is one way of doing so.

Bird feeder in the snow
It is time to use a bird feeder, even for a sceptic like me

I never thought I would say the word “birdfeeder”, even if three out of every four households use them and more than £200 million is spent every year on birdfeed[x]. I avoided birdfeeders for a long time, as I considered them to be unnatural. Mostly the larger birds took over and kept the smaller birds away. The jackdaws were especially troublesome and would work in packs of four. Two would be Top Gun and keep the other birds at a distance, while the remaining pair would take turns to gobble what seed they could. The blue tits and robins never stood a chance. Thanks to the frost and snow, I have given up the fight, and my birdfeeder is out once more. So far, I have seen no jackdaws, so the smaller birds are tucking in with gusto. I must hope it stays that way.


To establish how I might be doing with insects, some months ago I sought to obtain an invertebrate survey for my land. It has now been completed and returned, having been capably undertaken by Peter Brash Ecology[xi]. Peter paid four day-long visits to my property over approximately six months and his findings have been remarkable.


Ultimately, to encourage insects is all about food chains and food webs[xii]. A food chain is a linear network of links in a food web starting from producer organisms such as grass or algae, which produce their own food via photosynthesis, and ending at an apex predator species, such as grizzly bears or killer whales. A food chain also shows how organisms are related to each other by the food they eat. Each level of a food chain represents a different trophic level. A trophic level is the location of an organism on the food chain for that ecosystem and is typically divided into five levels. Level 1 is a primary producer, Level 2 a primary consumer, Level 3 a secondary consumer, Level 4 a tertiary consumer, and Level 5 is an apex predator. Natural interconnections between food chains make it a food web. It seems evident that with a downturn in the number of insects, everything above them on the food chain will suffer[xiii], and that includes mankind.

Siberian Tiger in the snow (andreaskrappweis)
The Siberian Tiger is top of apex predators (andreaskrappweis)

Instinctively, one might think that mankind is at the apex of all food chains and is an apex predator. Not true. In 2013, a team of French scientists set out to answer where exactly humans were on the food chain[xiv]. They found that humans are many rungs below apex predators. This is because mankind depends on a varied diet, including fruits, vegetables, grains, and proteins. The proteins typically come from Level 2 animals such as chickens, cows, fish, and pigs. That makes mankind barely more than a Level 2 animal, which is the same as an anchovy or pig. The top apex predator in the world happens to be the Siberian Tiger[xv].


With mankind so far down the list, and nowhere near its top, it is perhaps worth asking what benefits humans provide Planet Earth, other than to themselves. Many have struggled to find an honest answer. My favourite response came from Scotland, which concluded that apart from maintaining rat populations, the only other value of humans was as a food source for blood-sucking insects. Bats and birds feed on such insects, which places mankind below insects in that particular food chain[xvi]. We are not always below insects, as sometimes mankind is just above. Two billion people worldwide eat insects as part of their traditional diet[xvii].

Swarm of bees in flight (GlobalP)
The existence of mankind depends on insects (GlobalP)

The moment one realises that mankind is simply another species, and an animal just like the rest, so insects become critical, as they form an essential part of our ecosystem. What might happen if insects did not exist? Plenty it seems, as the consequences would be catastrophic for ecosystems, agriculture, and human life. Insects have many critical roles in the environment, and their absence would trigger a domino effect across various ecological, agricultural, and economic systems. For example:


1. Collapse of Food Webs and Loss of Biodiversity: Insects are a key part of many food webs, serving as primary consumers of plants and as prey for a wide range of animals, including birds, amphibians, reptiles, and mammals[xviii]. Without insects, these predators would struggle to find alternative food sources, leading to a decline in their populations[xix]. This disruption in food webs would have a cascading effect, potentially leading to the collapse of entire ecosystems and a significant loss of biodiversity[xx].


2. Disruption of Pollination: Many plants, including numerous crops, depend on insects for pollination[xxi]. Without insects, these plants would fail to reproduce successfully, leading to a decline in plant diversity[xxii]. This would particularly impact flowering plants, including fruits, vegetables, and nuts, severely affecting the availability and variety of these foods[xxiii].


3. Soil Degradation: Insects such as beetles play a vital role in maintaining soil health[xxiv]. They help decompose organic matter, aerate the soil, and increase its nutrient content[xxv]. Without these services, soil quality would deteriorate, adversely affecting plant growth, reducing agricultural productivity, and increasing the need for artificial fertilisers[xxvi].

Andromeda lacebug (Stephanitis takeyai)(courtesy Peter Brash)
An Andromeda lacebug - a pest to some but welcome on my land (courtesy Peter Brash)

4. Increase in Pest Populations: Some insects, such as ladybugs, lacewings, and predatory wasps, help control populations of other insect pests[xxvii]. Without these natural predators, pest populations could explode, causing severe damage to crops and forests[xxviii], so insects are one way of maintaining balance[xxix]. Without this, there could lead an increased reliance on chemical pesticides, which can have harmful environmental and health consequences[xxx].


5. Loss of Ecological Services: Beyond pollination and pest control, insects provide other ecological services such as nutrient cycling and decomposition. Their absence would disrupt these processes, affecting ecosystem functioning and resilience[xxxi].


6. Economic Impact: The disappearance of insects would have a substantial economic impact, especially in agriculture and related industries. The cost of pollination services alone, predominantly performed by bees, is estimated to be billions of US dollars globally[xxxii]. The loss of these services would strain agricultural production and economies, particularly in regions that are heavily dependent on agriculture[xxxiii].


7. Human Health Issues: Insects play a role in controlling the spread of disease. For example, certain mosquito species help control populations of other mosquitoes that spread diseases such as malaria and dengue fever[xxxiv]. Additionally, insects are used in biomedical research, thereby contributing to advances in medicine and health[xxxv].

Tupiocoris rhododendri (courtesy Annie Smith)
Tupiocoris rhododendri - a Lakeland first (courtesy Annie Smith)

It is simple to see how a world without insects would be unrecognisable and a struggle for mankind to survive. However selfish we may be as a species, we depend on insects, perhaps even more than they depend on us. It follows that insects must be preserved and encouraged, whatever the difficulties of doing so. It is why so much of my renaturing is about insects, and why I sought an invertebrate survey for my land. I needed to know if I was doing the right thing, or should I join the many others who seem set on destroying the environment around them, blaming everyone other than themselves?

The survey found 189 different species of insect. I am told that is plenty. Of these, more than 50% were associated with open habitats, and nearly 30% with trees. If there was ever a reason to preserve my trees, the fear of losing one-third of my insect species is that reason.


Two species were new to Lakeland, and both were plant bugs. The first was Tupiocoris rhododendri[xxxvi]and the second was Stephanitis takeyai[xxxvii], or the Andromeda lacebug. Both were probably accidental introductions to the UK. The former originated in the USA, the latter from Japan. There were other rare insects as well and far too many to summarise here. My land is in Westmorland, for which there are no records of several insects that were found. These were Coelositona cambricus[xxxviii] - a type of weevil, Ptinus subpilosus[xxxix] - a beetle, and Asaphidion curtum[xl] - a form of ground beetle.

Chafer grub
A chafer grub appeared by the young sycamore

What the survey has shown is that my land is a haven for insects, so I must keep that in mind with everything I do. Without insects there would be no mankind, at least not for long. Now I realise their importance, I find it easier to spot insects on my land. Beforehand I was clearly passing them by without thinking. These days the bugs have my focus, although with snow on the ground there are not many to see.


Beyond the survey, when I was transplanting the sycamore, I came across a chafer grub[xli] deep within my soil. The grub will in due course become a chafer beetle, on which larger animals can feed. Those larger animals, perhaps a badger, fox, or carrion, can cause extensive damage to gardens. It is why so many folk use pesticides to eliminate the chafer beetle, which is seen as a pest. In my case I will leave it, as that is what renaturers do.

***



Acknowledgement

Take it from me - none of this would be possible without the help of RSG Horticulture. Rufus, who runs it, has far more energy than me and is full of ideas and skills. Do contact him through https://www.rsghorticulture.com.



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References [i] See weeks 4, 6, 23, 34, 38, 39 and 48 entries. [ii] See weeks 2, 23, and 48 entries. [iii] See weeks 3, 4, 23, 26, 44, and 48 entries. [iv] Staking Trees. See https://www.trees-online.co.uk/Staking-Trees#:~:text=Remove%20the%20stake%20and%20tie,to%20re%2Dtie%20or%20not. Accessed 1 December 2023. [v] Frost. See https://www.forestresearch.gov.uk/climate-change/risks/frost/#:~:text=Impact%20of%20frost&text=The%20increase%20in%20stress%20may,leaf%20fall%20or%20shoot%20hardening. Accessed 1 December 2023. [vi] RHS. Polystichum. Shield fern. These handsome ferns are mainly evergreen and will give you interest in the garden throughout the year. Use them in a shady spot under trees or around large shrubs. They can also be used in shady or semi-shady borders for foliage interest or to contrast with plants such as hostas. They are among the hardiest of all ferns you can grow in gardens. See https://www.rhs.org.uk/plants/polystichum. Accessed 1 December 2023. [vii] See weeks 6, 10, and 43 entries. [viii] Wikipedia. John Muir. John Muir (April 21, 1838 – December 24, 1914), also known as "John of the Mountains" and "Father of the National Parks", was a Scottish-born American, naturalist, author, environmental philosopher, botanist, zoologist, glaciologist, and early advocate for the preservation of wilderness in the United States. See https://en.wikipedia.org/wiki/John_Muir. Accessed 1 December 2023. [ix] Bugs Matter survey finds that UK flying insects have declined by nearly 60% in less than 20 years. 5 May 2022. See https://www.buglife.org.uk/news/bugs-matter-survey-finds-that-uk-flying-insects-have-declined-by-nearly-60-in-less-than-20-years/#:~:text=A%20citizen%2Dscience%20survey%2C%20led,%2Dfocussed%20conservation%20research%2C%20nationwide. Accessed 1 December 2022. [x] Should I feed birds? Pros and cons. See https://gardenbirds.net/should-i-feed-birds-pros-and-cons/. Accessed 2 December 2023. [xi] See https://peterbrashecology.co.uk. Accessed 1 December 2023 (under construction). [xii] Food chain. See https://en.wikipedia.org/wiki/Food_chain#References. Accessed 1 December 2023. [xiii] Eat and be eaten: the fundamental role of insects in the food chain. 15 July 2019. See https://m.espacepourlavie.ca/blogue/en/eat-and-be-eaten-fundamental-role-insects-food-chain#:~:text=The%20thing%20is%2C%20in%20being,energy%20to%20the%20next%20level. Accessed 1 December 2023. [xiv] Bonhommeau S, Dubroca L, Le Pape O, Barde J, Kaplan DM, Chassot E, Nieblas AE. Eating up the world's food web and the human trophic level. Proc Natl Acad Sci U S A. 2013 Dec 17;110(51):20617-20. doi: 10.1073/pnas.1305827110. Epub 2013 Dec 2. PMID: 24297882; PMCID: PMC3870703. [xv] Top 10 apex predators in the world. See https://factanimal.com/fun-stuff/apex-predators/#:~:text=Topping%20the%20list%20of%20the,eastern%20Russia%20and%20northeastern%20China. Accessed 1 December 2023. [xvi] Downie B. Do humans provide any benefit to planet Earth other than for ourselves? 9 June 2021. See https://www.newscientist.com/lastword/mg25033382-600-do-humans-provide-any-benefit-to-planet-earth-except-for-ourselves/. Accessed 2 December 2023. [xvii] Halloran A, Münke-Svendsen C, Huis A, Vantomme P. Insects in the human food chain: global status and opportunities. Food Chain 2014;4:103-118. 10.3362/2046-1887.2014.011. [xviii] Wilson EO. The little things that run the world (the importance and conservation of invertebrates). Conservation biology. 1987 Dec 1:344-6. [xix] Paine RT. Food web complexity and species diversity. The American Naturalist. 1966 Jan 1;100(910):65-75. [xx] Dirzo R, Young HS, Galetti M, Ceballos G, Isaac NJ, Collen B. Defaunation in the Anthropocene. Science. 2014 Jul 25;345(6195):401-6. [xxi] Ollerton J, Winfree R, Tarrant S. How many flowering plants are pollinated by animals? Oikos. 2011 Mar;120(3):321-6. [xxii] Klein AM, Vaissière BE, Cane JH, Steffan-Dewenter I, Cunningham SA, Kremen C, Tscharntke T. Importance of pollinators in changing landscapes for world crops. Proceedings of the royal society B: biological sciences. 2007 Feb 7;274(1608):303-13. [xxiii] Potts SG, Biesmeijer JC, Kremen C, Neumann P, Schweiger O, Kunin WE. Global pollinator declines: trends, impacts and drivers. Trends in ecology & evolution. 2010 Jun 1;25(6):345-53. [xxiv] Lavelle P, Decaëns T, Aubert M, Barot S, Blouin M, Bureau F, Margerie P, Mora P, Rossi JP. Soil invertebrates and ecosystem services. European journal of soil biology. 2006 Nov 1;42:S3-15. [xxv] Brussaard L, De Ruiter PC, Brown GG. Soil biodiversity for agricultural sustainability. Agriculture, ecosystems & environment. 2007 Jul 1;121(3):233-44. [xxvi] van der Putten WH, de Ruiter PC, Bezemer TM, Harvey JA, Wassen M, Wolters V. Trophic interactions in a changing world. Basic and Applied Ecology. 2004 Dec 13;5(6):487-94. [xxvii] Landis DA, Wratten SD, Gurr GM. Habitat management to conserve natural enemies of arthropod pests in agriculture. Annual review of entomology. 2000 Jan;45(1):175-201. [xxviii] Symondson WO. Molecular identification of prey in predator diets. Molecular ecology. 2002 Apr;11(4):627-41. [xxix] How predators and parasites are useful to nature. See https://espacepourlavie.ca/en/how-predators-and-parasites-are-useful-nature. Accessed 1 December 2023. [xxx] Pimentel D. Environmental and economic costs of the application of pesticides primarily in the United States. Environment, development and sustainability. 2005 Jun;7:229-52. [xxxi] Wall DH, Nielsen UN, Six J. Soil biodiversity and human health. Nature. 2015 Dec 3;528(7580):69-76. [xxxii] Gallai N, Salles JM, Settele J, Vaissière BE. Economic valuation of the vulnerability of world agriculture confronted with pollinator decline. Ecological economics. 2009 Jan 15;68(3):810-21. [xxxiii] Losey JE, Vaughan M. The economic value of ecological services provided by insects. Bioscience. 2006 Apr 1;56(4):311-23. [xxxiv] Juliano SA. Species interactions among larval mosquitoes: context dependence across habitat gradients. Annual review of entomology. 2009 Jan 7;54:37-56. [xxxv] Andre RG, Wirtz RA, Das YT, An C. Insect models for biomedical research. Nonmammalian animal models for biomedical research. 1989 Nov 30:61. [xxxvi] Wikipedia. Tupiocoris rhododendri. A species of bugs in Miridae family that can be found in the United States in European countries such as Belgium, Germany, United Kingdom, and the Netherlands. The species have black pronotum with brown wings and yellow legs and feeds exclusively on rhododendron. See https://en.wikipedia.org/wiki/Tupiocoris_rhododendri. Accessed 2 December 2023. [xxxvii] Wikipedia. Stephanitis takeyai. The andromeda lace bug (Stephanitis takeyai) is a pest insect on plants of the genus Pieris, especially Pieris japonica, the Japanese andromeda. It originated in Japan with its host plant but has since been introduced to other areas of the globe. See https://en.wikipedia.org/wiki/Stephanitis_takeyai. Accessed 2 December 2023. [xxxviii] Category:Coelositona cambricus See https://commons.wikimedia.org/wiki/Category:Coelositona_cambricus. Accessed 2 December 2023. [xxxix] Ptinus subpilosus. See https://en.wikipedia.org/wiki/Ptinus_subpilosus. Accessed 2 December 2023. [xl] Asaphidion curtum. See https://en.wikipedia.org/wiki/Asaphidion_curtum. Accessed 2 December 2023. [xli] Chafer grubs are the soil-dwelling larvae of chafer beetles. Depending on the species of chafer they either feed on decaying plant material or plant roots. Some, which are do not cause damage in gardens are found in borders and compost heaps. However, some species that feed on the roots of grasses can cause problems in lawns. Chafer beetles belong to the beetle family Scarabaeidae, which consists of dung beetles and chafers and is represented over 80 species in Britain. Many species are rare or of local occurrence. A majority are dung feeders and vitally in the recycling and disposal of dung. Around 17 species are chafer beetles some feed on decomposing organic matter, others on plant roots only a handful of species can cause damage in gardens. See https://www.rhs.org.uk/biodiversity/chafer-grubs-in-lawns. Accessed 2 December 2023.


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