What a nerve


Like most people who have heard about the recent poisonings in Salisbury involving a nerve agent, I feel, to say the least, it is shocking. I don't feel qualified to comment on the matter except to say that news coverage did grab my attention when the presenters and commentators spent a little while explaining to the listeners what nerve agents are and broadly how they work.

It was interesting to hear that the nerve agent used in the Salisbury poisonings appears to be something produced in the Cold War era (possibly more than 40 years ago). The substance named as the poison used in Salisbury was one of a number developed during the 1960s to 1990s. Chemical nerve agents have been around since before WW2. They are highly toxic chemicals made as weapons that act to block certain nerve pathways. Anything that interferes with those pathways immediately impacts bodily functions that rely upon communication through the nervous system. The bodies organs are affected and so normal functions and behaviours are impacted. Impacted may be an understatement since the purpose of the nerve agent is to incapacitate or kill. Respiration and heart function are affected very quickly.

It happens that the first nerve agents were organophosphate compounds and their potential as weapons was discovered, by chance, in 1936 as a German company worked to develop new insecticides. The work on developing and manufacturing these compounds became priority work during WW2 and of course highly secret. After the war, commercial interest and manufacturing capacity shifted back to insecticides for agricultural use. So let us pause briefly and reflect. Nerve agents have their roots in insecticide development.

The concerns about the wide toxic effects of organophosphate compounds drove the work to find alternatives. There was a period when it was thought that natural insecticides  present in some plants, for example, chrysanthemums might be the answer. That gave us pyrethrum based formulations and these were popular for a while particularly for garden use by the average gardener. However the effectiveness was insufficient for industrial agriculture and probably not very commercially attractive to manufacturers so further work led to the exploration of other natural compounds with insecticidal properties, nicotine was a likely candidate (any connection with finding an alternative use for the declining popularity of tobacco is probably a figment of my imagination). Again it worked for some insects. Next the search shifted to developing synthetic nicotine lookalikes with greater potency, commercial potential and consistent formulations convenient and predictable for use in agriculture. A group of compounds named neonicotinoids (new nicotine like compounds) became available for agriculture and garden use in the 1990s. Another brief pause for reflection - pyrethrum, nicotine and neonicotinoids all act on the insects nervous system - they are nerve agents.

Neonicotinoids' genesis may be traced from natural compounds toxic to insects and evolved in chrysanthemums and tobacco plants to protect themselves against insect damage. It is claimed by manufacturers of neonicotinoids that even though they are nerve agents their impact is on insect nervous systems and not on the nervous systems of humans. That does not stop me from worrying when I here that neonicotinoid residues are commonly found in our food. Anyway that is a question for a later blog piece perhaps.

The issue here and now is to draw attention to the fact that at this time of heightened interest and concern about a Cold War nerve agent used in Salisbury, we should not forget the historical and chemical link between insecticides and chemical weapons of war. Neonicotinoids are now subject to various controls and bans because of their damaging effects on bees, even at sub-lethal concentrations these compounds have been found to interfere with the bees nervous systems leading to an inability to feed and communicate vital information to fellow foragers. 


So what of the ecology of small spaces with regard to insecticides. The management of small spaces, particularly publicly accessible small spaces, can and should be undertaken without resort to chemical pesticides, (insecticides, herbicides, fungicides and all the others). The use of such chemicals is undesirable as avoiding public contact with sprayed areas cannot be guaranteed. Also there is no convincing commercial argument to support their use in such environments.

Not spraying allows insects to survive. Many insects are attractive, many provide food for birds and bats, many are beneficial pollinators. On this occasion I'll make a plea for five species of attractive butterfly all found on The Park. They are, Small tortoiseshell, Peacock, Red admiral, Comma and Painted lady. They have been present most years (in the 10 years that I have been observing).

Assuming we don't spray to kill their larvae - why would we? All of these beautiful butterflies familiar to me from childhood (except the Comma which I only met since moving to The Park) have something in common. That common factor brings me back to the ongoing theme of my blog pieces, demonised wild plants.

Without the counter balancing awareness that these butterflies' existence relies heavily upon a particular wild plant as a food source for their larvae (caterpillars), it is easy to dislike or fear Urtica dioica, the Common stinging nettle.

The Common stinging nettle. On one occasion a neighbour on The Park suggested to me that a patch of stinging nettles should be removed in case a child touched them and got stung. I never heard of anyone dying from touching a stinging nettle. In fact I remember my own childhood experiences of rather unpleasant nettle stings, I still get them from the odd invading nettle coming under the garden fence. I don't enjoy it but philosophically I am reminded that sometimes plants with succulent leaves have evolved mechanisms to discourage herbivores. Clearly my five butterflies larvae are tolerant. Wonderful thing evolution! Regarding the succulent leaves, nettles have for centuries been picked when young and used in cooking and salads and medicinally too.

When too tough to use in cooking, nettles will compost to produce a fortifying plant food. The stems yield a fibre that has been used in ways similar to linen.

Just as a final remark in defence of The common nettle, it occurs as at least six sub-species found in different parts of the world. Its ability to evolve to survive in different soils and climates is worthy of our interest and reflection before seeking to eradicate it.



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