That’s the phrase often used to describe the insect population insects are often described as. They make up 70% of all animal species and there are somewhere between 5-10 million species of these creepy crawlies. Only about a million of these have been catalogued but the vast majority remain unknown – 1.5 million of these are beetles.
On a global scale there are 1.4 billion insects per human being, but insect numbers are widely reported to be declining worldwide. No one can put a figure on just how much because the most rapid rates of decline are taking place in regions of the world where there is least monitoring.
It could be said the canary in the coal mine is beginning to gasp for breath. At the same time agriculture is experiencing increases in problem pests and for the past 70 years the answer has been to spray insecticides. The problem is that now the drugs aren’t always working. In fact it can be argued that they’re doing a lot more harm than good when looking at the bigger picture because of the effect they may have on non-target species and beneficials.
It’s an all too familiar picture this season, with oilseed rape crops succumbing to cabbage stem flea beetle and record numbers of aphids happily passing viruses around as they feed on sugar beet and potato crops. Cereals aren’t immune either, with BYDV set to become a much greater problem than it’s been for many years. All of these pest problems lead us back to the neonicotinoids, or lack of them. But in all probability, the neonics may have contributed to the current state of the nation by masking a problem that was developing anyway and has undoubtedly accelerated in the wake of their ban through the desperate (over) use of pyrethroids.
So where do we go from here? Like medicine, our industry has developed along the lines of treating symptoms – there’s a pest eating the crop so spray it. Seldom do we look for causes – why is the pest eating the crop? Why has it become a pest? What do I know about it? Seldom do we consider the consequences to other insect species – many of which have a function in a healthy ecosystem that isn’t even known.
But perhaps it’s time to take notice of the canary and take a long, hard look at the how we can manage pests in the future. Cabbage stem flea beetle is an interesting case-in-point and it was a surprise to me that we actually know so little about it. One of the suggestions often raised as a means of making OSR viable again is to zone production – if OSR growing was ceased in an entire area for a season or two then would CSFB numbers subside to a manageable level?
As it turns out, it’s not known how far a CSFB will fly when it migrates into crops in the autumn. It could be 5 miles, 50 miles or 500 miles – so without this very crucial piece of the puzzle there’s no way of predicting whether such measures could work.
We don’t know where CSFB go to have a bit of a snooze between crops. Is it to a nearby hedge or do they find another crop to shelter peacefully in? Then there’s the question, why has CSFB become such a big pest? They were around before the neonic seed treatments but admittedly controllable using insecticides. Then along came the neonics and CSFB were mostly a problem of the past.
But if neonics were so effective, why was it that numbers were building up anyway during the two decades they were widely used? Is that due to climate change or the loss of other potent insecticides which may have had an inadvertent effect on CSFB numbers? Or could it be changes in the rotation such as the introduction of cover crops?
Understanding exactly what’s gone wrong in our farming system is part of finding a sustainable solution moving forward because it’s a system that is fundamentally broken – the canary is telling us that much.
More and more UK growers are stepping off the industrial treadmill – looking for solutions to these problems from the soil up, looking at ways they can support plant health and bring some balance back into their farming system. It’s very much a science-based ‘alternative therapy’ rather than the ‘prescribed medicine’ approach that, just maybe, can help get the canary singing once again.
Based in Ludlow, Shrops, CPM technical editor Lucy de la Pasture has worked as an agronomist. @Lucy_delaP
