A word which has taken its place in the horticultural vocabulary in recent years is the lengthy – and difficult to spell – ‘neonicotinoids’.
It’s not even easy to pronounce; and yet many gardeners use them regularly without being clear exactly what they are and the full ramifications of what they do. So what are they and what do they do?
Neonicotinoids are systemic insecticides which farmers, plant nurseries and gardeners spray to kill aphids such as greenfly and blackfly and root-feeding grubs like weevils. They are extensively used world-wide; and they are called ‘systemic’ insecticides because the plants on which they are sprayed absorb them and transport them throughout their entire system from root to flower. The virtue of this to the grower is that insect pests which feed on any part of the plant ingest the neonicotinoids, which paralyse and kill them. The downside for the insect world is that all insects which feed on the plants ingest the neonicotinoids, resulting in the deaths of large numbers of beneficial insects on which we … the world’s human population … depend to pollinate and fertilise many of the almost-infinite variety of plants which share our world. And these plants are not just attractive additions to our environment; they provide much of our food either directly … in the form of seeds, leaves, shoots and roots … or indirectly in the form of the animals, fish and birds which we eat and which have, of course, relied on the seeds, leaves, shoots and roots of plants for their food.
We have suspected for years that neonicotinoids have been taking their toll of beneficial insects: but we have been pretty good at accepting that the heavy loss of life in what we see as insect pests was worth the collateral damage to what we regard as the beneficial insect population … principally the bee population. But recently, German scientists have reported that a 25-year-long study of insect populations has revealed a staggering 75% drop in the total insect population of their country and have suggested that it is very likely that there has been a similar reduction in insect populations all around the world. ‘Insect Armageddon’ is the term they have applied to this collapse, warning that this decrease in insects could have disastrous consequences for agriculture, as well as ecosystems as a whole.
I suspect that this reduction in the insect population has been going on for longer than this study might suggest, for I remember the so-called ‘bug deflectors’ … miniature plastic snow ploughs which replaced the radiator caps atop the bonnets of cars … of my early adult years. (How many people can even remember that the radiator caps on cars used to be on top of the bonnet rather than concealed beneath it?) These devices minimised the number of flying insects which died, splattered messily across the windscreen. Is this a problem today?
Here in the United Kingdom, the Department for the Environment, Food and Rural Affairs (DEFRA) created a pollinator strategy in response to the large scale use of neonicotinoids, urging large-scale growers to create pollinator habitats adjacent to areas treated with these insecticides. But spray drift on to these habitats affects wild flowers too. Maybe we all … farmers and gardeners alike … have to come to terms with the fact that insecticides containing acetamiprid, clothianidin, imidacloprid, nitenpyram, nithiazine, thiacloprid and thiamethoxam … and many common garden insecticides are based on one or more of these neonicotinoids, particularly imidacloprid … are not just bad news for insects; they are seriously bad news for our entire planet, including us. So, gardeners, read the labels on pesticide packs; look for imidacloprid in particular; and give it a miss for all of our sakes!