Hi, welcome to Taiga Bonsai, in this article we discuss some of the insects that are devastating both agriculture and horticulture.

Introduction – borers are perhaps the most harmful to trees, they originate from many countries causing great damage to native species that have no defence. How they were introduced to the western hemisphere is predominantly via wooden packaging.

The Asian Longhorned beetle – Anoplophora glabripennis native to eastern China, and Korea has been introduced into the United States, where it was first discovered in 1996, and in Canada and several countries in Europe including, Austria, France, Germany, Italy and UK.

A. glabripennis primarily infest maple, poplar, willow, and elm trees. In the United States it has attacked birch, katsura, ash, planes and Sorbus. In Canada on maple, birch, poplar, willow and in Europe on maple, alder, birch, hornbeam, beech, ash, planes, poplar, Prunus, willow and Sorbus.

The Bronze Birch borer – Agrilus anxius a wood-boring buprestid beetle native to North America, numerous in warmer parts of the continent where it thrives. It is a serious pest on birch trees Betula frequently killing them. If this insect came to Europe there would be no hope for Birch forests, as the trees have no resistance against this species of insect. Hence the effect on Scandinavia’s Birch industry would be devastating.

The Emerald Ash Borer Agrilus planipennis, a devastating alien pest of ash trees was first detected in Europe and in Moscow in 2003. Its outbreak in the cities of Europe and Russia seriously damaged plantations of Ash trees Fraxinus pennsylvanica. It was introduced from North America.

This alien pest posing a major threat to ash trees all over Europe has spread to Ukraine and the south of Europe severely damaging the green ash F. pennsylvanica. Research indicates that will appear in other European countries soon with the potential to destroy F. pennsylvanica plantations.

The Chinese emerald ash borer found its way to America via international shipping, when it gained its freedom. It was greeted with a fresh new smorgasbord of North American ash trees Fraxinus americana, thus making itself a new home in which to reside. To date the amount of devastation to millions of ash trees is now in the tens of millions across 25 states.

Airborne invasion – we know that many pests and disease have migrated throughout the world by conventional methods. In packaging containing merchandise and sometimes in the merchandise itself. Mainly via land sea and air.

However, these modes of transportation is not the only way for pests and disease to migrate to other realms. There are those whom are able to take to the wing and reach altitudes of 2,000m some actually fly, whilst other drift on the air currents.

For example, the Desert Locust Schistocerca gregaria a periodically swarming, short-horned grasshopper from Africa, destroys thousands of hectares of crops on its migration eastwards. These pests can easily reach and altitude of 2,000ms and cover a distance of up to 200 km in a single day.

Those that tend to drift on the air currents and travel vast distances include pathogens that are microscopic, the average size of most bacteria is between 0.2 and 2.0 micrometre, (diameter). Fungal spores typically range in size from 2 to 50 μm in diameter, with most allergenic spores in the respirable size range of 3 to 10 μm.

Such pathogens when earthbound are able to create their own colonies if conditions allow. They can attack vulnerable vegetation including food crops, flowering/fruiting plants and trees. At this juncture methods of control are inadequate. The old adage that ‘Prevention is better than cure’ is meaningful, but the devastation of these ‘unseen enemies’ only becomes visible when it is too late to react.

Sirex wood wasp Sirex noctilio a species of horntail native to Europe, Asia, and North Africa. Is an invasive species in other realms including Australia, New Zealand, North and South America and South Africa, where it has become a significant economic pest of pine trees especially Pinus radiata.

The wasp can attack a wide variety of pine species, although some species seem to be more susceptible than others and stressed trees often are attacked. It is believed that this insect was introduced on unprocessed pine logs imported from Europe.

P. radiata were first planted in the late nineteenth century in Australia, Chile, New Zealand and in South Africa during the early 1900’s. Their excellent growth provided the basis for thriving lumber and paper industries.

During 1920’s and 30’s the lumber industry stagnated because the demand for small logs from thinning operations decreased. This made plantations susceptible to S. noctilio and its associated fungus, Amylostereum areolatum. By 1947, high levels of tree mortality were occurring, primarily in the un-thinned plantations causing devastation to the lumber and paper industries.

Adult sirex wood wasps vary in size from 9 to 36 mm (0.35 to 1.42 in), during oviposition the female will lays 2 eggs often with a mucoid substance and a symbiotic fungus to feed on once hatched. This mucoid substance is toxic to trees as are the ascospores from symbiotic fungus Amylostereum areolatum. A species of crust fungus originally called Thelephora areolata, it was given its current name by French mycologist Jacques Boidin in 1958.

The hidden menace – Dutch elm disease (DED) first appeared in the north-west of Europe about 1910. Between 1914 and 1919, several Dutch scientists carried out influential research on the cause of the disease. According to https://www.forestresearch.gov.uk this disease “Is one of the most serious tree diseases in the world.”

The fungus that causes the disease is spread by bark beetles triggering foliage and tip dieback in all of Britain’s native elms. Including the English elm Ulmus procera, smooth-leaved elm U. carpinifolia and wych elm U. glabra. The disease first spread to Britain in the 1920s, where it killed 10-40% of elm trees. Although the initial epidemic died down, a more aggressive species of Dutch elm disease fungus was accidentally introduced into Britain in the 1960s.

A second epidemic took hold of lowland central and southern Britain where there were English elms in the early to mid-1970s and by 1980. Most mature English elms had died. Although scattered pockets of mature elm occasionally survived, where the geographic situation has facilitated an effective and continuing sanitation control program.

By the late 1980s the bark beetles used up most of the mature elms that they relied on for breeding material. Hence beetle populations declined and the disease virtually disappeared from many southern and south-western areas.

In 1982, Forestry Commission research on the biology of Ophiostoma novo-ulmi, an extremely virulent species from Japan has devastated elms in Europe, North America, Asia and now is spreading across across Eastern Europe. (Romania to Poland)

This suggested that the disease would not decline in intensity or contrast to the first epidemic, caused by O. ulmi. The new pathogen, O. novo-ulmi, would return in a continuing cycle to attack the following generation of small elms once they were large enough to support beetle breeding.

Cryphonectria parasitica a pathogenic fungus a member of the Ascomycota (sac fungi) native to East Asia and south-east Asia. It was introduced into Europe and North America in the early 1900s spreading rapidly causing significant tree loss in both regions.

This disease came to be known as ‘chestnut blight’ due its infestation of Chestnut trees Castanea dentata and has had a devastating economic and social impact on communities in the eastern United States.

Once a tree begins to decline it is often dead within a few years and eradication efforts by cutting and burning the infected plants/trees have mostly failed; at this present juncture there are no chemical management options for control.

Thus far the consequences of mankind’s actions over the millennia do not paint a good picture. In fact the problems we have tried to solve many of which we cannot are only increasing at an alarming rate.

As stated there are no chemical management options for control, should we concentrate our efforts to find more potent solutions to eradicate pests and disease; we have already tried this approach with negative consequences. Until next time, BW, Nik.

Hi, welcome to Taiga Bonzai, we have written articles on a selection of pests and disease recently. As a result our followers (horticulturists and bonsai enthusiasts) have asked for further research on this subject.

Introduction – in the last article we concluded our discussion on the ‘Toxicity’ of various shrubs and trees and their potential to be mildly irritant to being potentially fatal. However, all flora regardless of their ability to defend themselves are prone to attack from pests and disease. This increasing problem creating havoc on the world’s horticulture production and effect on society, is not a new phenomenon; it is the result of mankind’s actions.

Since the dawn of time – mankind’s actions have caused catastrophic consequences in many ways, the world is facing unprecedented challenges that will be extremely difficult to resolve. Have we reached the point of no return? Some believe that we have past it, others are more complacent, ‘These situations need to be addressed but they can be resolved’.

During our travels around the globe we have been privy to some extraordinary and amazing locations, returning to them at a later date we note that many have been destroyed. Piles of rubble, barren land, some are now heavily polluted – rife with pestilence and disease. Such experiences do not wane, they remain strong and clear in the mind. How have we arrived at this juncture? Follow our journey as we try to shed some light on the issue.

The beginning – according to scientific research vegetation had evolved on Earth approximately 700 million years ago with fungi and bacteria approximately 1,300 million years prior. This evidence is based on the earliest fossils of those organisms. The general consensus is that organisms also called microbes are beneficial for example, they keep nature clean by helping break down dead plants and animals into organic matter.

Mankind’s contribution – the hunter-gatherer culture developed among the early hominins of Africa, with evidence of their activities dating as far back as 2 million years. According to Richard B. Lee & Richard Daly (Cambridge Encyclopedia: Hunters and Gatherers) “Was humanity’s first and most successful adaptation, occupying at least 90 percent of human history“.

In addition, it is understood that through archaeology, anthropology, genetics, linguistics and the advent of writing from primary and secondary sources, this information is relatively common knowledge.

Colin Tudge in his book ‘Neanderthals, Bandits and Farmers: How Agriculture Really Began’. New Haven, CT: Yale University Press (1998) contends that “The Neolithic saw the Agricultural Revolution begin between 10,000 and 5000 BC in the Near East Fertile Crescent” (Mesopotamia). During this period humans began the systematic husbandry of plants and animals and agriculture advanced.

Many humans transitioned from nomadic to a settled life style as farmers in permanent settlements. The relative security and increased productivity provided by farming allowed communities to expand into increasingly larger units, fostered by advances in transportation.

However, Alina Polianskaya of ‘ Inews.co.uk‘ (March 15th 2018) points out that “Early humans may have been trading with each other much earlier than previously thought. Scientists excavated ancient artefacts at Middle Stone Age sites dating back 300,000 years at the Olorgesailie Basin, in southern Kenya. They uncovered weapons made of materials that could not be found there, suggesting hominins at the time may have exchanged goods with others.”

In his paper ‘Evolution: What Makes a Modern Human’ Nature. 485 (7396) (2012) Chris Stringer tells us that “Modern humans spread rapidly from Africa into the frost-free zones of Europe and Asia around 60,000 years ago.” This notion is supported by Adam Hart-Davis in his work ‘History: The Definitive Visual Guide’. New York: DK Publishing.

He contends that “The rapid expansion of humankind to North America and Oceania took place at the climax of the most recent ice age. At the time, temperate regions of today were extremely inhospitable. Yet, by the end of the Ice Age, some 12,000 years ago, humans had colonised nearly all ice-free parts of the globe“.

The Silk Road – a network of trade routes connecting China and Far East with the Middle East and Europe, was established when the Han Dynasty in China officially opened trade with the West in 130 BC. Although these Silk Road routes were protected from exterior forces by the Han and other countries under signed treaties, pests and disease also travelled with the traders.

This lead to infection, sickness and often death, because those who came into contact with these infectious bacteria had no immunity for example. October 12, 1492, the day when Christopher Columbus landed on the island of Guanahaní (San Salvador now part of the Bahamas.) The beginning of what was yet to come.

The Silk Road routes remained in use until 1453 AD, when the Ottoman Empire boycotted trade with China and closed them. It has been nearly 600 years since the Silk Road was used for international trade, but the routes have had a lasting impact on commerce, culture and history that resonates today and are being reopened.

International trade is arguably the most important factor in the modern world, as nations rely on others to supply the many types of commerce they need. Agreements are signed to lessen the bureaucracy nonetheless, international trade does bring problems as we shall find out in this series.

Yet some countries enforce stringent rules on imports for example, Australia probably has the strictest regulations on what is imported. Meat products, fruit and plant material including seeds from many countries including Asia and Middle East are prohibited.

However, some are permitted if the exporter is registered and has the required documentation. Unlike the rest of the world Australia (although having its own disease problems) is free of many other known diseases and has been since 1872, due to stringent pre and post-border measures. Meanwhile the rest of the world continues to battle with disease containment.

Today much has changed, we have advanced – science and technical horticultural knowledge has allowed us to become adept in food production. New plant species have been introduced, more variety and apparently more taste – but have we gone too far?

The reason why this question is asked is because for every action there is a reaction often resulting in irreversible consequences. Now pests and disease endemic to a particular part of the world are now commonplace in many other regions where flora has no defence.

How this phenomenon occurred is partly due to the fact that pests and disease are able to migrate via wind and wing over vast areas for example. The locust derived from the Latin locusta, in the family Acrididae a swarming insect that devastates vast areas of crop land is able to fly up to 2000 metres covering 200km per day.

Between June 2019 and February 2022, a major outbreak of desert locusts began developing, threatening food supplies in East Africa, the Arabian Peninsula and the Indian subcontinent. The outbreak was the worst to hit Kenya in 70 years, and the worst in 25 years for Ethiopia, Somalia, and India.

However, pests and disease are transmitted by other means including packaging, cross contamination, from animals, by dust suspended in the air and by food and water. But in the main it is the consequence of our actions, for which mankind is ultimately responsible. In the next article of ‘Unseen invasion’ we look at some examples of this, until next time, BW, Nik.

Hi welcome to Taiga Bonzai, we continue our discussion on pests and disease with a selection of beetles whom bore their way into the trunk of trees. The damage caused by these insects is often results in the tree’s demise.

Introduction – borers are perhaps the most harmful to trees, they once were endemic to certain parts of the globe, but are now found in other parts of the world. Eradication of these insects is an on going battle with no conclusive results.

Airborne invasion – we know that many pests and disease have migrated throughout the world by conventional methods, in the packaging containing merchandise and sometimes in the merchandise itself; mainly via land sea and air.

However, these modes of transportation are not the only way for pests and disease to migrate to other realms. There are those whom are able to take to the wing and reach altitudes of 2,000m some actually fly, whilst other drift on the air currents.

Dutch elm disease (DED) – first appeared in the north-west of Europe about 1910 and between 1914 and 1919, several Dutch scientists carried out influential research on the cause of the disease. According to Forest research.gov.uk this disease “Is one of the most serious tree diseases in the world.” The fungus that causes the disease is spread by bark beetles triggering foliage and tip dieback in all of Britain’s native elms: Ulmus procera, U. carpinifolia and U. glabra. https://www.forestresearch.gov.uk

The disease first spread to Britain in the 1920s, where it killed 10-40% of elm trees. Although the initial epidemic died down, a more aggressive species of Dutch elm disease fungus was accidentally introduced into Britain in the 1960s.

This second epidemic took hold of lowland central and southern Britain where there were English elms in the early to mid-1970s and by 1980, most mature English elms had died. Scattered pockets of mature elm occasionally survived where the geographic situation has facilitated an effective and continuing sanitation control programme.

By the late 1980s the bark beetles used up most of the mature elms that they relied on for breeding material, so beetle populations declined and the disease virtually disappeared from many southern and south-western areas.

In 1982, Forestry Commission research on the biology of Ophiostoma novo-ulmi, an extremely virulent species from Japan has devastated elms in Europe, North America, Asia and now is spreading across across Eastern Europe. (Romania to Poland)

This suggested that the disease would not decline in intensity or contrast to the first epidemic, caused by O. ulmi. The new pathogen, O. novo-ulmi, would return in a continuing cycle to attack the following generation of small elms once they were large enough to support beetle breeding.

Cryphonectria parasitica  – a pathogenic fungus a member of the Ascomycota (sac fungi) native to East Asia and south-east Asia was introduced into Europe and North America in the early 1900s spreading rapidly causing significant tree loss in both regions.

This disease came to be known as ‘chestnut blight’ due its infestation of Chestnut trees Castanea dentata, it has had a devastating economic and social impact on communities in the eastern United States. Once a tree begins to decline it is often dead within a few years and eradication efforts by cutting and burning the infected plants/trees have mostly failed. At this present juncture there are no chemical management options for control.

Sirex wood wasp – (Sirex noctilio) a species of horntail native to Europe, Asia, and North Africa is an invasive species in other realms. These include Australia, New Zealand, North and South America and South Africa, where it has become a significant economic pest of pine trees especially Pinus radiata.

The wasp can attack a wide variety of pine species, although some species seem to be more susceptible than others and stressed trees are often attacked. It is believed that this insect was introduced on unprocessed pine logs imported from Europe.

P. radiata were first planted in the late nineteenth century in Australia, Chile, New Zealand and in South Africa during the early 1900’s. Their excellent growth provided the basis for thriving lumber and paper industries. During 1920’s and 30’s the lumber industry stagnated, because the demand for small logs from thinning operations decreased.

Hence thinning ceased which made plantations susceptible to S. noctilio and its associated fungus, Amylostereum areolatum. By 1947, high levels of tree mortality were occurring, primarily in the un-thinned plantations causing devastation to the lumber and paper industries.

Adult sirex wood wasps vary in size from 9 to 36 mm (0.35 to 1.42 in), during oviposition the female will lays 2 eggs often with a mucoid substance and a symbiotic fungus to feed on once hatched.

This mucoid substance is toxic to trees as are the ascospores from symbiotic fungus Amylostereum areolatum a species of crust fungus originally called Thelephora areolata. It was given its current name by French mycologist Jacques Boidin in 1958.

The Asian Longhorned beetle – Anoplophora glabripennis native to eastern China, and Korea has been introduced into the United States, where it was first discovered in 1996. Also in Canada and several countries in Europe including, Austria, France, Germany, Italy and UK.

This beetle is believed to have been spread from Asia in solid wood packaging material. A. glabripennis primarily infest maple, poplar, willow, and elm trees. In the United States it has attacked birch, katsura, ash, planes and Sorbus. In Canada on maple, birch, poplar and willow and in Europe on maple, alder, birch, hornbeam, beech, ash, planes, poplar, Prunus, Sorbus and willow.

The Bronze Birch borer – Agrilus anxius is a wood-boring Buprestid beetle native to North America, numerous in warmer parts of the continent where it thrives. It is a serious pest on birch trees Betula frequently killing them. If this insect came to Europe there would be no hope for Birch forests, as the trees have no resistance against this species of insect; hence the effect on Scandinavia’s Birch industry would be catastrophic.

The Emerald Ash Borer – Agrilus planipennis, a devastating alien pest of ash trees was first detected in Europe in Moscow in 2003. Its outbreak in the cities of Western Russia seriously damaged plantations of Ash trees Fraxinus pennsylvanica introduced from North America.

This alien pest posing a major threat to ash trees all over Europe, has spread to Ukraine and the south of Western Russia. It severely damages the green ash F. pennsylvanica, research indicates that will appear in other European countries soon with the potential to destroy F. pennsylvanica plantations.

The Chinese emerald ash borer often referred to as The green menace found its way to America via international shipping. When it gained its freedom it was greeted with a fresh new ‘smorgasbord’ of North American ash trees Fraxinus americana. To date the amount of devastation to millions of ash trees is now in the tens of millions across 25 states.

European spruce bark beetle – Ips typographus, is a species of beetle in the weevil sub family Scolytinae, they are endemic from Europe to Asia Minor and some parts of Africa. Bark beetles are so named because they reproduce in the inner bark of living and dead phloem tissues of trees. In ideal conditions they can travel up to almost a kilometre (½ a mile) in search of a vulnerable host.

Once the host is located, the adult burrows through the weakened bark in order to build tunnels where they can mate and lay eggs. They release pheromones to attract more individuals to the host tree. Two to five weeks after contamination, they may migrate to another host and repeat the process.

European bark beetles have the ability to spread rapidly over large areas and trees in the genera Picea (spruce), Abies (fir), Pinus (pine), and Larix (larch) are this beetles’ trees of choice. Healthy trees use defences by the production resin or latex, which may contain several insecticidal and fungicidal compounds; that kill or injure attacking insects. However in many cases this form of defence is overwhelmed by this pest. 

The insects (from Latin insectum) mentioned here are hexapod invertebrates, the largest group within the arthropod phylum. They are able to create their own colonies if conditions allow, attacking vulnerable vegetation of all types. At this juncture methods of control are inadequate, the old adage that ‘Prevention is better than cure’ is meaningful. But the devastation of ‘unseen invasion’ only becomes visible when it is too late to react.

What we have mentioned here is but a very brief glance into the world of hexapod invertebrates. In the next article of ‘Unseen invasion’ we continue our discussion on more of these harmful pests that are a constant threat to horticulture and bonsai. Until next time, BW, Nik.

Hi welcome to Taiga Bonzai, in this article we discuss some of the possible reasons of why we are unable to stem the onslaught of pests and disease.

Introduction – the increasing problem of invading pests and disease devastating agriculture, horticulture, natural woodlands and forests across the globe. A problem that is now making headlines around the world.

The decline – over the last few decades there has been an increasing decline in the insect population. Disappearing are many helpful predators including, Ladybugs Coccinellidae, Green Lacewings Chrysopidae, Honey Bees genus Apis, Praying Mantis family Mantidae, Spiders family Arachnida, Ground Beetles family Carabidae, Soldier Beetles family Cantharidae, Assassin Bugs family Reduviidae and Robber Flies. Asilidae

These insects are part of the food chain they eradicate unwanted pests including aphids, scale, mealy bugs and saw fly and in turn are the main resources for many birds, small mammals, fish, reptiles and other creatures.

Moreover, they are an important key for human food production because, many crops depend on insects for pollination leading to fruit and seed production. Insects play a very important role in decomposing organic matter allowing nutrients to return to the soil and support the on coming crop season. Therefore, in terms of insect ecological importance, a sharp decline in their abundance is of great concern.

The arguments – here are the points view from others whom are mindful of this issue. Will de Freitas asks if we are facing insect Armageddon he states that, “A recent study found that German nature reserves have seen a 75% reduction in flying insects over the last 27 years. The researchers involved made stark warnings that this indicated a wider collapse of the general insect population that would bring about an ecological catastrophe if left unchecked.” (article – October 25, 2017 – The Conversation)

Damian Carrington Environment editor for The Guardian in his article (10th February 2019) argues that “The world’s insects are hurtling down the path to extinction, threatening a catastrophic collapse of nature’s ecosystems.”

“More than 40% of insect species are declining and a third are endangered, the analysis found. The rate of extinction is eight times faster than that of mammals, birds and reptiles; the total mass of insects is falling by a precipitous 2.5% a year, according to the best data available.”

In the February 2020 journal Biological Conservation no, 242 (a leading international body of scientists in the discipline of conservation science) Editor in chief Vincent Devictor of the Institut des Sciences de L’Evolution de Montpellier, France stated that. “We are causing insect extinctions by driving habitat loss, degradation and fragmentation, use of polluting and harmful substances. The spread of invasive species, global climate change, direct over exploitation and co-extinction of species dependent on other species.”

Devictor goes on to say that “With insect extinctions, we lose much more than species. We lose abundance and biomass of insects, diversity across space and time with consequent homogenization, large parts of the tree of life, unique ecological functions and traits and fundamental parts of extensive networks of biotic interactions. Such losses lead to the decline of key ecosystem services on which humanity depends.”

According to http://www.magnificentmeadows.org.uk “The UK’s remaining rich grasslands now cover a minute fraction of the area they once covered, even relatively recently in the early 20th Century. There were once natural wildflower meadows in every parish – today only 2% of the meadows that existed in the 1930’s remain. Nearly 7.5 million acres of wildflower meadow have been lost so far and they are still being destroyed.”

The blame game – these are but a few of the arguments from scientists and conservationists from the many we have researched and from these points of view it appears we have a major situation on our hands. There are many theories as to the decline in insect populations they include, habitat destruction by intensive farming and urbanisation, pesticide use, introduced species, climate change, eutrophication from fertilisers, pollution and artificial lighting; the latter used in huge polyethylene tunnels for intensive crop production.

Yet, despite the scientific evidence provided, globally our performance in instigating effective insect conservation is below par, we need to realise this fact and act accordingly. This would involve more inclusive education, better decisions with land managers and government officials in maintaining unique habitats, across the globe. To have more expansive sustainable agriculture and forestry, improved regulation and prevention of environmental risks and greater recognition of protected landscapes.

But the frailty and idiosyncrasy of human nature is what it is, the world’s heads of state congregate at summits and conferences to find ways to solve problems, each pointing the finger blaming the other for their misgivings when they themselves are equally responsible for the same actions. It is fickleness, bureaucratic hypocrisy by the asinine in an attempt to maintain ‘stability’, (economic, environmental and social or profits, planet, and people) a mind set proposed for the wealthy not the masses.

As the world’s population increases so does the demand for more sustainability in food production. We know that pests and disease from all corners of the globe are a major threat to all countries, resulting in irreversible changes to environments.

Insects are a major component of the tapestry of life and failure to protect them will have dire consequences. Moreover, they are our natural defence in stemming the increasing onslaught. It is now time for heads of state and their minions to refrain from ‘putting their heads in the sand’ and listen to the scientists to prevent a ‘Bug apocalypse.’

Thus far we know the present situation and the problems we now face, but how did it get to this stage? In the next article we look at some of the causes that have created this catastrophe during the last 70 years, until next time, BW, Nik.