Tag Archives: conservation headlands

Ten papers that shook my world – Lewis (1969) – the importance of (h)edges for natural biological control

In 1969, Trevor Lewis, of what was then the Rothamsted Research Station (now Rothamsted Research), published two landmark papers (Lewis 1969ab). These papers, in which he described the importance of hedges as habitats for insects (Lewis, 1969a) and in acting as possible sources of natural enemies able to colonise nearby fields (Lewis, 1969b) were to have a profound effect on me and generations of applied entomologists and pest mangers to the present day.

In 1976 the UK experienced what is now recognised as the warmest year of the 20th Century.  It was also the year that I started my final year as an undergraduate.  Before entering our final year we had to do a research placement or project.   I opted to do my project at home, I was making very good money as a temporary postman and as I usually finished my round by 10 am, I had plenty of time during the rest of the day to get to grips with my project.  I had come across the Lewis papers in lectures and thought that it would be interesting to do a similar study; given the weather I was also keen to spend as much time outside as possible 🙂 My Uncle James owned a local farm and was happy for me to sample some of his hawthorn hedges, so sampling hawthorn hedges was what I did during July and August of the glorious summer.

Simon summer 1976

The intrepid student entomologist; trusty bike, clipboard and a copy of Chinery*. Note the wellington boots despite the heat 🙂

The hedges

The hedges in question – three types of management

As I mentioned earlier, 1976 was the warmest year on record at the time, and I see from my report that during August I was recording temperatures in excess of 25oC, even in the hedge bottoms.

Hedges project

The report

What is interesting is that although 1976 was one of the famous ladybird outbreak years (in fact last week I was interviewed by the BBC about my memories of that very same event) I didn’t record more than a handful of ladybirds in my surveys.  Perhaps inland Yorkshire just wasn’t attractive enough 🙂

Overall my results showed that over-clipping resulted in more crop pests being present and that hedges with less clipping supported a greater diversity of insect life than the more managed ones, very similar to results being reported today (e.g Amy et al., 2015).

Sadly, although Lewis’s two 1969 papers and to a certain extent his earlier paper in a much harder to access source (Lewis, 1964), led on to the concept of conservation headlands (Sotherton et al., 1989) and ‘crop islands’ (Thomas et al., 1991), which are an integral part of European Union subsidised farm payments, it was included in an influential review article (van Emden & Williams, 1974).  As pointed out recently by Terry McGlynn over at Small Pond Science, this often rings the death knell for a paper’s citation score.  As a result,  Lewis (1969b) has only been cited 91 times since 1969 and is barely remembered at all.   I remember being invited to be a facilitator at a Populations Under Pressure conference workshop on this very subject at the NERC Centre for Population Biology at Silwood Park about fifteen years ago and being surprised that none of the participants had even heard of Trevor Lewis let alone read his papers.

Simon PUP

At the Populations Under Pressure conference brandishing my undergraduate hedgerow report!

The subject of hedgerow and crop edge management is still a highly important research area today, and you will be pleased to know that in the latest paper just submitted from my research group, we cite both of Trevor’s 1969 papers. Hopefully this will do something to redress the balance and bring Trevor some of the recognition that he deserves, however belated.



Amy, S.R., Heard, M.S., Hartley, S.E., George, C.T., Pywell, R.F. & Staley, J.T. (2015) Hedgerow rejuvenation management affects invertebrate communities through changes to habitat structure. Basic & Applied Ecology, 16: 443-451

Chinery, M. (1973) A Field Guide to the Insects of Britain and Northern Europe.  Collins, London

Lewis, T. (1964). The effects of shelter on the distribution of insect pests. Scientific Horticulture, 17: 74–84

Lewis, T. (1969a). The distribution of flying insects near a low hedgerow. Journal of Applied Ecology 6: 443-452.

Lewis, T. (1969b). The diversity of the insect fauna in a hedgerow and neighbouring fields. Journal of Applied Ecology 6: 453-458.

Sotherton, N.W., Boatman, N.D. & Rands, M.R.W. (1989) The “Conservation Headland” experiment in cereal ecosystems. The Entomologist, 108: 135-143

Thomas, M.B., Wratten, S.D., & Sotherton, N.W. (1991) Creation of ‘island’ habitats in farmland to manipulate populations of beneficial arthropods: predator densities and emigration. Journal of Applied Ecology, 28: 906-917.

Van Emden, H.F. & Williams, G.F. (1974) Insect stability and diversity in agro-ecosystems. Annual Review of Entomology, 19: 455-475

*I still own that copy of Chinery which was a present for my 20th birthday – take note of the date if anyone wants to send me a present or card 🙂






Filed under Ten Papers That Shook My World

Pest Managers are ecologists too

Over the course of the last decade I have come to the conclusion that British undergraduates have no idea of what pest management actually is.  For the last twenty years or so, I have run a suite of MSc courses, initially at the Silwood Park campus of Imperial College and since 2012, at Harper Adams University, the leading land-based university in the UK.  The four MSc courses I run are Conservation and Forest Protection, Ecological Applications, Entomology and Integrated Pest and Disease Management.  These are, as you can see, pretty much specialist vocational courses.  The students who do these courses are highly motivated and come from a range of backgrounds.  Many had established careers in other areas and found those careers lacking.  Others have had a burning desire to embark on advanced training in entomology since they were at school and been deeply frustrated that no undergraduate degrees exist in the UK in that subject. [The last BSc in Entomology in the UK was awarded in 1993 by Imperial College to Andy Salisbury (now Dr Andrew Salisbury and Senior Entomologist at the Royal Horticulture Society’s research offices at Wisley].  Yet others have developed an interest in one of the areas covered by my MSc courses as undergraduates and decided to make a career in those areas, but found that their BSc degrees had not prepared them to the required level in their chosen subject and that they needed the extra training provided by a postgraduate course.  The interesting thing to me is how the absolute interest in integrated pest management has remained at pretty much the same level year on year, at just under 5 with a high of 9 students in 1989 and in 1998 no students at all.  Over the same period the average number of entomologists on the course was twelve. As a proportion of the student body the pest management contingent has ranged from a very disappointing zero to the memorable year, 2004, when there were twice as many pest managers as entomologists, albeit out of total student body of only nine.

MSc Entomology and IPM students

MSc Entomology and IPM students

Pest managers are in great demand from industry –biological control and agrochemical companies have more positions than there are suitably qualified graduates; yet undergraduates seem reluctant to train in this area.  I think that there are two root causes for this problem; a lack of exposure to the subject as undergraduates and a misunderstanding of exactly what pest managers are and what they actually do.  Mention pest management to most people, not just students, and their first reaction is rats, cockroaches and Rentokil operatives spraying.



The mythical spray man

The mythical spray man

A pest!

A pest!

Yes pest control does involve poisoning vermin and spray operations against domestic insect pests, but that is only one very minor, albeit important, aspect of pest management.  Pest management, or as it is more formally known, Integrated Pest Management, is the intelligent selection and use of pest control measures to ensure  favourable economic, ecological  and sociological consequences.  Yes this does include the use of pesticides but only as part of an integrated programme that could include biological control, the use of resistant plant varieties, and the diversification of the farm landscape through conservation headlands, and cultural methods such as crop rotation or inter-cropping.   Even scare-crows, traditional or modern, can be part of an IPM programme. The list goes on and all this is backed up by a detailed knowledge and understanding of the biology and ecology of the pest species, their natural enemies and the habitats that they live in.

Conservation headland

Conservation headland

Traditional scarecrow

Traditional scarecrow



Biological control

Biological control

The idea of pest management is not an entirely modern one ; Benjamin Walsh a British born pioneer applied entomologist  working in the USA, said in 1866, and I quote,  “Let a man profess to have discovered some new patent powder pimperlimplimp, a single pinch of which being thrown into each corner of a field will kill every bug throughout its whole extent, and people will listen to him with attention and respect.  But tell them of any simple common-sense plan, based upon correct scientific principles, to check and keep within reasonable bounds the insect foes of the farmer, and they will laugh you to scorn”.  I consider this to be the first modern reference to integrated pest management.


Pest managers do not just work in domestic and urban situations.  Most pest managers, as opposed to pest control operatives work in agriculture, forestry and horticulture, safeguarding our crops and ensuring global food security.  Pest managers, because of the complexity of the problems facing sustainable crop production in the modern world, have to have a much greater depth and breadth of knowledge than pure ecologists.   Although many pest managers have entomological backgrounds, they also have a more than nodding acquaintance with plant pathology, nematology and pesticide application and chemistry.  They also need to have a good grasp of the economics of both pest control and the farming/cropping system that they are working in.  They must fully appreciate what is feasible and appropriate in the context of the farmer’s/forester’s year, budgets and targets in terms of yields and profits.  There is no point in coming up with the ideal ecological or conservation solution that cannot be implemented because of the constraints of the real world.  Pest managers, even those working in academia, interact closely with their end-users, to ensure a reduction in pest numbers and abundance, not necessarily eradication, which is acceptable to growers, society and the natural world.   As Lorna Cole said on Twitter on September 8th 2013….

Lorna Cole

So when you hear the word pest management in future, don’t just think spray, think conservation headlands, beetle banks, biological control, crop rotation, resistant varieties, chemical ecology, forecasting, monitoring , cultural control, holistic farming, multi-purpose forestry, sociology, economics and sustainability.  These are the elements of the armoury most commonly used by pest managers, not pesticides as so many people mistakenly think.

So for prospective students, don’t be put off by the word pest, if you want an exciting, satisfying and possibly international career, embrace the application of ecology and make a difference to the world.   Become a pest manager.  Without integrated pest managers food production will never be sustainable or as ecologically friendly as it now is.

Post Script

Sadly, even to this day (it was much worse when I started my career), there is a perception among some academics that being applied is second best; on one memorable occasion I was introduced to some visitors by one of my colleagues as, “this is Simon Leather, he’s an ecologist, ALBEIT, an applied one”


Post post script


For those interested in joining the MSc course in Integrated Pest Management based at Harper Adams University here is the appropriate link.  I should also add that unfortunately we are NOT able to offer three annual Scholarships funded by the Horticultural Development Council, HDC, of £5000 each to particularly deserving students as despite ALL our graduates finding employment in the industry they felt that the scheme was not working!


Filed under Bugbears, EntoNotes