Tag Archives: pest management

Crop Protection Summer School – CROPSS 2019 – the grand finale?

The first week of July was a happy time but also a sad time.  I was privileged and very happy to spend a week with sixteen enthusiastic undergraduates keen to learn about crop protection, but at the same time, sad that the BBSRC funding to run my Crop Protection Summer School has now come to an end. Last year at this time I wrote about how pleased I was with the positive response of the students to working in, what to them, was a totally novel subject area.

Like last year, the Summer School started on a sunny Sunday afternoon, with an introduction from me about why crop protection was important and how Integrated Pest Management is all about ecology, NOT spraying and eradication, something I have been banging on about for many years and which needs to be reiterated again and again, so here I am reiterating it yet again 😊.

Our Sunday evening venue for the last two years, The Lamb Inn, the pub closest to the university, is closed at the moment so we

had to take a couple of taxis (large ones) to an alternative watering hole, The Last Inn. I was relieved to find that it was an excellent choice and we had a magnificent meal which I interrupted periodically to remind the students that they were also supposed to be doing a Pub Quiz 😊

As with last year, the quiz was all picture rounds.  The first round was all about charismatic megafauna (almost all answered correctly), then common British wild flowers (about 60% correct), common British trees (50% correct), common British insects (30% correct), I think you can see where I am going with this😊  This year, however, one of the teams cored 100% on the insect round thanks to the presence of an extremely keen entomologist, which meant I couldn’t feign resigned disappointment as much as I have in the past.

Catering for the rest of the week was in our excellent campus refectory and as last year, the students were all very complimentary about the quality of the food and the choices available.

We continued with the successful format of previous years, with specific days allocated to the main crop protection areas, agronomy, entomology, nematology, plant pathology, weed science and spray technology. Each evening after dinner, we had a speaker from ‘industry’; Jen Banfield-Zanin, a former student of mine who works at from Stockbridge Technology Centre, Rob Farrow from Syngenta, Bryony Taylor from CABI, Nicola Spence the Chief Plant Health Officer and Neal Ward from BioBest.  They were all very well received and had to answer a lot of interesting questions, both in the classroom and in the Student Union Bar afterwards.

The students and staff involved found it a very rewarding week, and as I did last year, I will let the pictures tell the story.

Let’s go on a nematode hunt! Matt Back briefing his troops

Sweep nets and pooters

Suction sampling with Andy Cherrill

Looking for weeds with John Reade

Labs and classrooms

Glorious weather and fantastic plants

Science communication and chasing fluorescent beetles in the dark

I think they liked the course and we loved their enthusiasm and commitment.

This year we did take the picture when we are all there!

Just to remind you why we need a well-trained youthful cadre of crop protection scientists.



I do hope that we will be able to secure some further funding to enable us to continue with this excellent initiative.  Perhaps the AHDB, the British Society of Plant Pathology and the Royal Entomological Society might consider chipping in?

Many thanks to Matt Back, Andy Cherrill, Louisa Dines, Simon Edwards, Martin Hare, Valeria Orlando, John Reade and Fran Sconce who all gave of their time freely to help deliver the course and to those MSc students who came and joined us in the bar.  I am especially grateful to our external speakers and their inspirational stories of how they ended up in crop protection.


Filed under Teaching matters

Ten Papers that shook my World – Root (1973) – When more means less – crop diversity reduces pest incidence

I can’t remember when I first read this paper but judging by the record card and the state of the actual hard copy of the paper, it was probably when I was doing my PhD in the late 1970s. This paper and its companion, which was published a year earlier* (Tahvanainen & Root, 1972), have had a significant effect on the scientific understanding and development of inter-cropping as a method of crop protection worldwide. Although inter-cropping in some form or another has been around a long time, the idea that it could be used as part of an integrated pest management programme was not proven.  In this landmark study, Root compared pure stands (plots) of collards (spring greens in the UK) (Brassica olercaea) with adjacent rows of collards grown intermingled with other herbaceous plants.  His premise being that it was well documented that pest outbreaks tend to be associated with pure monocultures of crops (Pimentel, 1961; Janzen, 1970) and he wished to test the hypothesis that natural enemies were more abundant and effective in vegetationally diverse areas  than in pure monocultures, the so-called ‘enemies hypothesis’.  This idea had been around a surprisingly long time e.g. Ullyett (1947) who remarked  “where weeds occur around headlands and in hedges, they should be left for the purpose of supporting parasites and predators important in the natural control of the diamond-back moth (Plutclla maculipennis Curt)”.  A decade later, Elton (1958,) refers to this statement, explaining that “these hedge rows form a reservoir for enemies and parasites of insects and mite pests of crops”.  I am not sure what it indicates but note that many groups around the world, including mine, are still working on this both at the local (field-scale) level (e.g. Ramsden et al., 2014) and landscape level (e.g. Rusch et al., 2013; Raymond et al., 2015).

Root explained the premise of the ‘enemies hypothesis’ as follows.  Predators and parasites are more effective at controlling herbivore populations in diverse habitats or plant communities because, diverse plant communities support a diversity of herbivores with a variety of phenologies, providing a steady supply of prey for the predators.  In addition, complex environments provide prey refugia, thus allowing the prey not to be completely eradicated.  Diverse plant communities also provide a broad range of additional resources for adult natural enemies e.g. pollen and nectar.

Root ran his experiment for three years and did indeed find a significant difference in herbivore load between the pure plots and the weedy rows, the former having a greater abundance of pests (mainly aphids and flea beetles) than the latter.

Fig 1

From Root (1973)

To his disappointment (I assume), he did not find any difference in the numbers of natural enemies between the two treatments. He thus had to come up with another idea to explain his results. His ingenious explanation is encapsulated in what he termed the Resource concentration hypothesis which states that herbivores are more likely to find and stay on hosts growing in dense or nearly pure stands and that the most specialised species often reach higher relative densities in simple environments.

Fig 2

Typical modern monocultures, beans, cabbages and wheat

He hypothesised that specialist herbivores were ‘trapped’ on the crop and accumulated whilst more generalist herbivores were able to and likely to move away from the crops to other host plants.  Root added that the ‘trapping effect’ of host patches depends on several factors such as stand size and purity.

In 1968, presumably as a result of what Root was discovering, Jorma Tahvanainen (one of the many great Finnish entomologists who appeared on the scene in the 1970s -, he retired in 2004) came to Cornell to do his PhD with Richard Root. Working on the same system and in the same meadow, Tahbanainen developed two new hypotheses to explain why more diverse cropping systems have fewer pest problems than monocultures. His experiments as he too found little evidence of natural enemies having an effect. He developed two new hypotheses, one he termed Associational resistance which I reproduce below exactly as published:

A natural community, such as a meadow, can be treated as a compound system composed of smaller, component communities (Root, 1973). The arthropods associated with different plant species represent important components in terrestrial systems. The available information indicates that the biotic, structural and microclimatic complexity of natural vegetation greatly ameliorates the herbivore pressure on these individual components, and consequently, on the system as a whole. Thus, it can be said that in a compound community there exists an “associational resistance” to herbivores in addition to the resistance of individual plant species. If the complex pattern of natural vegetation is broken down by growing plants in monocultures, most of this associational resistance is lost. As a result, specialized herbivores which are adapted to overcome the resistance of a particular plant species, and against which the associational resistance is most effective, can easily exploit the simplified system. Population outbreaks of such herbivores are thus more likely to occur in monocultures where their essential resources are highly concentrated

The other, is the Chemical Interference Hypothesis, in which he postulated that reduced herbivory in diverse communities due to chemical stimuli produced by non-host plants interfering with host finding or feeding behaviour of specialist herbivores.  His experimental set-up was very simple, but very effective.

Fig 3

How to send mixed signals to specialist herbivores – reproduced from Tahvanainen & Root (1972)

In simple terms, a monoculture sends out a very strong signal, it could be olfactory, e.g. a strong bouquet of crucifer volatiles, or for other herbivores it could be visual, or a combination of the two.

Fig 4

Conventional intensive agricultural landscape sending out strong ‘signals’ to specialist herbivores

Inter-cropping increases crop diversity and changes the crop ‘signal’ to one that now ‘confuses’ specialists. Note that I am not necessarily advocating a combined crop of wheat, beans and cabbages, as harvesting would be a nightmare 😉

Fig 5


The intercrop melange effect

These two papers have had a huge influence on the theory and practice of inter-cropping and agricultural diversification, although Root (1973) has had many more citations (1393 according to Web of Science on 11th December 2015) than Tahvanainen & Root (1972) which has only had a meagre 429 citation to date.  The message coming out from the many studies that have now investigated the effect of intercropping crop diversification on pest abundance, is, that in general, polyculture is beneficial in terms of promoting biological control and that incorporating legumes into the system gives the best yield outcomes (Iverson et al,  2014).

Another take on intercropping that overcomes the potential problems of harvesting different crops from the same field, is the concept of planting different genotypes of the same species. Resistant plants tend to have fewer generalists present, although their individual yield may be reduced.  By planting a mixture of susceptible and resistant genotypes it is however, possible to have your cake and eat it, especially if it is not essential to have a single genotype crop.  This approach has been used to good effect in the production of short rotation willow coppice, where planting diverse genotypes of the same species reduces both pest and disease levels (Peacock et al., 2000, 2001).

Who would have that two simple field experiments conducted in an abandoned hay meadow outside Ithaca, New York almost fifty years ago would have such a far-reaching influence?



Elton, C. S. (1958) The Ecology of Invasions by Animals and Plants. London: Methuen & Co., Ltd. 159 pp.

Iverson, A. L., Makin, L. E., Ennis, K. K., Gonthier, D. J., Connor-Barrie, B. T., Remfret, J. L., Cardinale, B. J. &Perfecto, I. (2014). Do polycultures promote win-win or trade-offs in agricultural ecosystem services? A meta-analysis. Journal of Applied Ecology. 51, 1593-1602.

Peacock, L. & Herrick, S. (2000) Responses of the willow beetle Phratora vulgatissima to genetically and spatially diverse Salix spp. plantations. Journal of Applied Ecology, 37, 821-831.

Peacock, L., Hunter, T., Turner, H., & Brain, P. (2001) Does host genotype diversity affect the distribution of insect and disease in willow cropping systems? Journal of Applied Ecology, 38, 1070-1081

Janzen, D.H. (1970) The unexploited tropics.  Bulletin of the Ecological Society of America, 51, 4-7

Pimentel, D. (1961). Species diversity and insect population outbreaks. Annals of the Entomological Society of America, 54, 76-86.

Ramsden, M. W., Menéndez, R., Leather, S. R. & Wackers, F. (2014). Optimizing field margins for biocontrol services: the relative roles of aphid abundance, annual floral resource, and overwinter habitat in enhancing aphid natural enemies. Agriculture Ecosystems and Environment, 199, 94-104.

Raymond, L., Ortiz-Martinez, S. A. &Lavandero, B. (2015). Temporal variability of aphid biological control in contrasting landscape contexts. Biological Control , 90, 148-156.

Root, R. B. (1973). Organization of a plant-arthropod association in simple and diverse habitats: the fauna of collards. Ecological Monographs, 43, 95-124.  1393 citations

Rusch, A., Bommarco, R., Jonsson, M., Smith, H. G. &Ekbom, B. (2013). Flow and stability of natural pest control services depend on complexity and crop rotation at the landscape scale. Journal of Applied Ecology, 50, 345-354.

Tahvanainen, J. & Root, R. B. (1972). The influence of vegetational diversity on the population ecology of a specialized herbivore Phyllotreta cruciferae (Coleoptera: Chrysomelidae). Oecologia, 10, 321-346. 429 citations

Ullyett, G. C. (1947) Mortality factors in populations of Plutella maculipennis Curtis (Tineidae: Lep.) and their relation to the problem of control. Union of South Africa, Department of Agriculture and Forestry, Entomology Memoirs, 2, 77-202.

Post script

*I suspect, judging by how the two papers cite each other, that the Root (1973) paper was actually submitted first but that the vagaries of the publication system ,  meant that follow-up paper, Tahvanainen & Root (1972) appeared first.

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Filed under Entomological classics, Ten Papers That Shook My World

When did research diversity stop being a good thing? Another threat to UK applied agricultural sciences

If, as is well documented, lack of diversity in cropping systems is bad for agricultural production (Johnson et al, 2006: Iverson et al., 2014), then those running the BBSRC should ask themselves why it is a good idea to reduce the number of UK universities they fund that are capable of first class work in the agricultural sciences, particularly crop protection.




Normally at this time of year I am desperately putting the finishing touches to a couple of applications for BBSRC Industrial CASE studentships (iCASE).   In past years, at the beginning of May, those of us in the majority of UK universities without access to Doctoral Training Partnership funding, make our way to the BBSRC Industrial CASE studentship page to check when the closing date for applications are.  Imagine my shock to find that “this inclusive, very successful and effective programme  appears to have been hi-jacked by the fat cats of the UK university sector.  Yet another example of the “haves” getting more at the expense of the “have-nots”.

BBSRC will no longer operate an annual competition for industrial CASE (iCASE) studentships, instead allocating the majority of these studentships to the BBSRC Doctoral Training Partnerships (DTP) for awarding alongside their standard studentships.  

“The decision to cease the annual iCASE competition for individual studentship projects was taken for a number of strategic and operational reasons, primarily in recognition that the cohort-based approach, as exemplified by the DTPs, provides the gold standard in modern bioscience training, and one which BBSRC was keen to ensure all our funded students had the opportunity to take advantage of”

A more cynical reading of this is ‘it saves the BBSRC administrative time and the costs associated with having to have the applications reviewed by the Training Awards Committee’.   I also take exception to the implication that the only universities in the UK that have a cohort-based training approach are those in receipt of a DTP.  At Harper Adams University we have a well-established cohort-based doctoral training system.  I would be very surprised indeed if we are unique in this aspect of our PhD training amongst the other 100 UK universities outwith the BBSRC DTP programme.

The BBSRC web site goes on to stare “In addition, it was agreed that devolving responsibility for the recruitment and selection of students and collaborators to the DTP partner organisations (of which there are in excess of 45 within 12 partnerships across the UK higher education and public sector research sectors) would improve links between them and local companies, and increase the ability of institutions to act quickly and agilely in allocating projects to these companies, without the delays associated with a large national competition.”

Having moved from a university with a BBSRC Doctoral Training programme and seeing the difficulty and lack of willingness that staff in the other Departments within the School had in finding industrial partners I lack confidence in the ability of such departments to improve links.  As applied, whole organism ecologists/biologists, my former colleagues and I, benefitted immensely from our more molecular-based colleagues’ lack of real industrial contacts and were able to make good use of their unused CASE allocations.  The named grant holder of the DTP grant at the time, told me during a coffee break at a BBSRC Training Awards Committee meeting that he felt the whole CASE scheme was a waste of money.

The iCASE scheme was an opportunity for first class researchers from DTP excluded universities and from ‘Cinderella’ disciplines, e.g. entomology, integrated pest management, non-molecular plant sciences, such as plant pathology, plant nematology, weed science and forestry, which are incidentally recognised by the BBSRC and other learned bodies as being nationally vulnerable ‘skill sets’ to obtain funding that they would otherwise not have access to.  It is a sad fact of life that the universities that hold BBSRC DTP grants long ago decided that possessors of the above vulnerable skill sets did not publish in high enough impact journals and either made them redundant or did not replace them when they retired.

The decision by the BBSRC to further disenfranchise those many excellent applied agricultural scientists is perverse and much to the detriment of UK agriculture.  Given the growing need for sustainable farming systems worldwide it is hard to understand or justify the thought processes that led to this very ill-judged decision.

Ironically it is not just those of us in universities without BBSRC DTP provision that found the removal of the iCASE scheme bothersome.  A day or so after my discovery of the death of iCASE I received an email from a friend of mine at another UK university which is part of a DTP.

 “On a separate issue – no doubt you’ll have registered BBSRC removing the iCASE fund.  Allegedly we will now absorb more projects into our regional  “Doctoral Training Partnership”, but as these are only 2.5 years  for the main project (after all the associated training) it doesn’t always lend itself to the same sorts of projects as iCASE”

And finally, just to highlight the vulnerable skills-sets issue that the BBSRC seems determined to worsen.  I am, as some of you may know, Editor-in-Chief of the Annals of Applied Biology.  I recently received this email from one of my Editorial Board, a whole organism plant pathologist with field experience.

“Dear Simon

 I think that the time has come for me to step down from the editorial board of the Annals of Applied Biology.  I have been doing this for fourteen or fifteen years and I am due to retire from my current post in the Agri-Food & Biosciences Institute in the next few months.

 It has been a privilege, and at most times, highly enjoyable to be part of the editorial board of Annals which is a really good journal.  In a highly competitive world AAB has maintained and indeed increased its reputation.  The standard of papers published is very high and the range of papers received from across the globe is sometimes astonishing.  It has certainly been frustrating at times identifying suitable referees for papers, and as research scientists seem to be under more and more pressure of time it is easy to understand why they are often reluctant to take on extra duties.  However peer review is at the very centre of how science works so it is important that everyone takes their responsibility seriously.

 I would love to be able to recommend a replacement but just now plant pathologists, certainly in the UK, are very thin on the ground.”

I contacted the President of the British Society of Plant Pathologists to see if he could offer me any suitable suggestions for a mid-career plant pathologist with field experience.  Sadly, the majority of  UK Plant Pathologists in the right age range with suitable publishing experience, are molecular biologists.  I eventually filled the gap, but had to appoint a Plant Pathologist from a US university, where happily, universities still recognise the need for field and whole organism plant pathologists and their importance in ensuring global food security; something that most research intensive UK universities and the BBSRC seem to have forgotten.


Iverson, A. L., Makin, L. E., Ennis, K. K., Gonthier, D. J., Connor-Barrie, B. T., Remfret, J. L., Cardinale, B. J. &Perfecto, I. (2014). Do polycultures promote win-win or trade-offs in agricultural ecosystem services?  A meta-analysis. Journal of Applied Ecology 51: 1593-1602.

Johnson, M. T. J., Lajeunesse, M. J. &Agrawal, A. A. (2006). Additive and interactive effects of plant genotypic diversity on arthropod communities and plant fitness. Ecology Letters 9: 24-34.


Post script

As I knew we were expecting a visit from Jackie Hunter the Chief Executive of the BBSRC, I deliberately held back posting this until I had had a chance to ask her directly about the demise of the iCASE scheme. Jackie was very willing to speak to me about this issue.  The main reason for the removal of the scheme appeared to be the costs of administration and of reviewing the proposals. She assured me that the interests of people like me had been taken into account by giving more money to the ten companies  which hold grants in their own right and also by expecting greater flexibility from the existing University DTP grant holders, by which I took to mean that they would be encouraged to collaborate with the ‘have-nots’. This may seem laudable were it not for two facts; of the ten industrial DTP holders, five are pharmaceutical companies holding just under half of the grants and the academic DTP grant holders are greatly lacking in agricultural expertise. I also suspect, given the shortage of available PhD studentships in comparison with staff numbers within most university departments, that a big stick will be needed to encourage any cross-fertilization with non-DTP holders. I will, however, wait and see if Jackie’s optimism is well-founded, although I will not be holding my breath 😉

Post post script

 The importance of diversification in research funding is not just a hobby-horse of mine.  See for example, this excellent post by Stephen Heard writing on why it is a bad strategy to centralise research funding.




Filed under Bugbears

Look Back in Angers – Teaching in France but not in French

I have long been aware of the Erasmus Programme (European Community Action Scheme for the Mobility of University Students) having had many Erasmus students in my classes over the years whilst at Imperial College.  It was however, only after moving to Harper Adams University, that I found out that there was also a similar programme to enable academic staff to spend time teaching at sister institutions.  I was contacted earlier this year by Joséphine Pithon from the Ecole Supérieure d’Agriculture d’Angers who wondered if I would like to come across to Angers a city I am ashamed to admit that I had very little knowledge of.  The chance of spending a week in France, my favourite holiday destination, was too good to turn down and my wife Gill was also very keen to have a short break and refresh her French language skills.  To cut a long story short, on Monday 24th March, we caught the Eurostar to Lille and then the TGV on to Angers, arriving mid-afternoon in, to our dismay, a very wet Angers.  We booked into our hotel, found somewhere not too far away to eat and then retired to deal with emails (sad to say we had both brought our laptops with us) and for me to double-check that my lectures were ready to deliver.
Tuesday dawned warm and sunny, much to Gill’s relief who had a day of sightseeing planned and I walked to ESA, which was only ten minutes away, collecting a roundabout on the way, albeit not as  spectacular as those in the south of France.

Roundabout Angers

 I arrived at a very welcoming ESA and managed to  make myself understood at reception and was introduced to my first class, a group of third years getting their first introduction to

ESA welcome

entomology.  It seemed to go well and despite me lecturing in English they asked a lot of pertinent questions. I then gave them two lectures on sampling and survey methods before going for lunch with my hosts.  I must give the staff canteen (cantine) a rave review – for less than €5 we got a three course lunch with coffee. Then it was back to lecture to a fourth year group about biological control and pest management, again to a very interactive group of students.  Then it was the short walk back to the hotel followed by an excellent meal in the city centre with my new French colleagues.  On the way we admired the bendy trams and marveled at the ingenuity of having ‘green’ tramways wherever possible.

 Tram  Tram lines

The next day I gave a seminar and then we headed out into the field with the third year students to collect insects and other invertebrates using a mixture of methods, pitfall traps, yellow pan traps, pooters, beating trays (known as Japanese umbrellas in French), sweep nets and extendable butterfly nets.  French students in the field are very similar in

Students getting briefed            Pan trap                Angers fieldwork

Extended net             Head first               Using  the pooter

behaviour to their British counterparts 😉  Then it was the end of the day and time to relax and find somewhere nearby to eat and get ready for a morning in the laboratory on Thursday.

Thursday morning was spent with the students helping them identify the various organisms that they had brought back from our day in the field.  It appears that whilst students have to wear lab coats staff are exempt!  Our lab manager at Harper Adams would never allow that; I am frequently being told off for popping into the lab sans coat.

Busy in the lab

In the lab I had to use my French a bit more as some students were better than others at English and in a one to one situation I feel a little less hesitant about demonstrating my inept language skills.  I think we all had a fun morning and learnt a lot from each other.  After an excellent lunch it was time for a break; there is no teaching at ESA on a Thursday afternoon so I was free to join Gill for an afternoon of sightseeing around Angers.  Needless to say it began to rain!  Nevertheless we saw the magnificent Château d’Angers, once the home of René I a most impressive building even in the rain and with a nice entomological surprise on the ramparts; beehives..

Chateau 2           Chateau                Bee hives

And of course a mini-vineyard complete with a rose bush at the end of the row to give early warning of mildew infections! Great to see pest management in action;-)

Vine yard  Rose at end of row

Thursday evening saw us at a great little restaurant in the city centre where we met up with Professor David Logan a plant physiologist at the University of Angers, and someone I had previously only met on Twitter.  He introduced us to a couple of very nice local wines and we had a superb (and very reasonably priced) meal. It was a great end to a fantastic and educational trip.  I think it is very impressive that the French students are willing and able to be lectured to in English.  I am ashamed to say that I think that very few of our own students would be able to cope with a week of teaching in French!

Given the chance I would definitely like to repeat the experience and spend more time there.

Post script
Whilst roaming the corridors of ESA I came across a departmental notice board where I saw this cutting from the February issue of the L’Éleveur laitier a French agricultural magazine, and was very amused to see how they portrayed British farmers!

How they see us





Filed under EntoNotes, Teaching matters, The Bloggy Blog