stop insects foraging on their leaves; the plants are better known as tobacco, and the chemical is a highly addictive natural product called nicotine.


In agriculture, insect damage is considerable, even in the UK - in the case of flea beetle in oilseed rape, yield losses, even in normal years, can be as high as 20%. In the search for more effective ways of insect management, scientists have looked at natural products and attempted to improve upon them. Hence, natural pyrethrums were replaced by more effective new versions called pyrethroids. Likewise, scientists also looked at nicotine’s mode of action. It was found that the “nicotine receptor” could be blocked by other nicotine-like compounds which were dubbed neonicotinoids. The advantage of both types of insecticide was their select effectiveness against certain insects in crops, coupled with a very low mammalian toxicity.


Running parallel to such scientific endeavours, the concerns about the indiscriminate use of insecticides, and pesticides in general, have led to a very sophisticated regulation system in the UK.


Regulatory Approval of Insecticides


Getting a new product to the market is extremely difficult, routinely taking ten years from the time that someone has observed that a compound has an effect on an insect, to the first sale of that compound. On average, the cost of doing so is £200 million, this having gone up by approximately 70% in the last ten years. The success rate of bringing a product to the market is currently one in 150,000, down from one in 38,000 in the 1980s, and one in 10,000 in the 1960s; the vast majority of the cost and rate of success is a direct result of the need to test for, and satisfy the demands of ever increasing regulatory aspects for human and environmental safety. Some of the aspects to be investigated are highlighted in Box 1.


Whether or not a pesticide passes these tests is also a long process, involving an assessment by the European Food Safety Authority and an in-depth analysis to decide


whether its use is appropriate within the UK. Essentially, all of the results are evaluated by government scientists at the Chemicals Regulation Directorate (CRD), a part of the Health and Safety Executive, who then make a recommendation to the Advisory Committee on Pesticides (ACP), a committee made up of independent medical, academic and other experts. By unanimous decision, this committee makes recommendations to Ministers who will grant an approval as appropriate. So, in agriculture, those


products which have a high intrinsic issue with bees are not normally allowed to be registered for use as a spray on flowering crops where bees will be foraging. On the other hand, they may be eminently suitable as a seed treatment, since beneficial insects such as bees will never come into contact with sufficient concentrations of the insecticide to pose any insect health issues. Hence, imidacloprid and


clothianidin neonicotinoid containing products are used as agricultural seed treatments. Conversely, thiacloprid, which is a neonicotinoid with a very positive bee health profile, can be used as a spray in the field, even on flowering plants.


Thus, when Bayer


CropScience developed Provado Lawn Grub Control to reduce the destructive presence of cranefly larvae and leatherjackets in lawns, the regulatory authorities will have reviewed the


information and determined that, since this product was to be used on mown grass, where there are essentially zero foraging opportunities for nectar seeking insects, the use of imidacloprid was entirely appropriate.


Bee Health


It is clear that honey bee health is in serious decline in the UK, Europe and North America, and that this is linked with severe infestations of a parasitic mite called Varroa destructor. Ironically, one of the best treatments for controlling this pest, up to now, has been a selective insecticide, such as Bayverol, a product produced by Bayer Animal Health. Unfortunately, in many cases, the Varroa mite has become resistant to this type of


Honey bee showing the effects of the Varroa mite


“It is clear that honey bee health is in serious decline in the UK, Europe and North America, and that this is linked with severe infestations of a parasitic mite called Varroa destructor”


treatment, in the same way as some weeds become resistant to some weedkillers, and how some bacteria become resistant to some antibiotics. In addition to Varroa, there


are a number of viral and fungal diseases that are damaging bee colonies throughout the UK. Exacerbating this are other parasites, such as Nosema,


which can reduce the lifespan of an infected young bee by nearly 80%.


While the decline in honey bee health is often billed as a global problem, there are countries that have relatively good bee health - Australia for example, which is free of Varroa. Countries that use the Africanised honey bee, rather than the European types, in


51


Box 1. Tests required for the Regulatory Approval of a Pesticide, which are set in the European Union


Efficacy - how good is an insecticide? Effects on crop? Yield and Quality? Impact on succeeding crops? Impact on adjacent crops?


Physical and chemical properties - Confirmation of identity, purity and structure. How soluble and stable is it? Is it flammable and how do you analyse it?


Toxicology/safety to animals/humans - How is it absorbed, distributed, excreted and metabolised? What is its potential to be toxic (short term, long term, etc)? If it does have the potential, in what way might it be toxic?


Ecotoxicology - What are its effects on birds, fish, aquatic invertebrates, algae, non-target plants, sediment dwellers, arthropods, bees, earthworms and soil micro-organisms? Does it have any impact on sewage treatment?


Residues - How is the product metabolised and distributed in the plant? What residues could occur in the crop or the succeeding crops?


Fate and behaviour in soil, water and air - What is the route of degradation of the product, and at what rate does it degrade? How mobile in the plant is it? Does it have the potential to leach into water courses and, if so, how much, how quickly?


Page 1  |  Page 2  |  Page 3  |  Page 4  |  Page 5  |  Page 6  |  Page 7  |  Page 8  |  Page 9  |  Page 10  |  Page 11  |  Page 12  |  Page 13  |  Page 14  |  Page 15  |  Page 16  |  Page 17  |  Page 18  |  Page 19  |  Page 20  |  Page 21  |  Page 22  |  Page 23  |  Page 24  |  Page 25  |  Page 26  |  Page 27  |  Page 28  |  Page 29  |  Page 30  |  Page 31  |  Page 32  |  Page 33  |  Page 34  |  Page 35  |  Page 36  |  Page 37  |  Page 38  |  Page 39  |  Page 40  |  Page 41  |  Page 42  |  Page 43  |  Page 44  |  Page 45  |  Page 46  |  Page 47  |  Page 48  |  Page 49  |  Page 50  |  Page 51  |  Page 52  |  Page 53  |  Page 54  |  Page 55  |  Page 56  |  Page 57  |  Page 58  |  Page 59  |  Page 60  |  Page 61  |  Page 62  |  Page 63  |  Page 64  |  Page 65  |  Page 66  |  Page 67  |  Page 68  |  Page 69  |  Page 70  |  Page 71  |  Page 72  |  Page 73  |  Page 74  |  Page 75  |  Page 76  |  Page 77  |  Page 78  |  Page 79  |  Page 80  |  Page 81  |  Page 82  |  Page 83  |  Page 84  |  Page 85  |  Page 86  |  Page 87  |  Page 88  |  Page 89  |  Page 90  |  Page 91  |  Page 92  |  Page 93  |  Page 94  |  Page 95  |  Page 96  |  Page 97  |  Page 98  |  Page 99  |  Page 100  |  Page 101  |  Page 102  |  Page 103  |  Page 104  |  Page 105  |  Page 106  |  Page 107  |  Page 108  |  Page 109  |  Page 110  |  Page 111  |  Page 112  |  Page 113  |  Page 114  |  Page 115  |  Page 116  |  Page 117  |  Page 118  |  Page 119  |  Page 120  |  Page 121  |  Page 122  |  Page 123  |  Page 124  |  Page 125  |  Page 126  |  Page 127  |  Page 128  |  Page 129  |  Page 130  |  Page 131  |  Page 132  |  Page 133  |  Page 134  |  Page 135  |  Page 136  |  Page 137  |  Page 138  |  Page 139  |  Page 140  |  Page 141  |  Page 142  |  Page 143  |  Page 144  |  Page 145  |  Page 146  |  Page 147  |  Page 148