Tag Archives: cereals

Ten more papers that shook my world – When it comes to plant-insect interactions its growth stage, not age that counts Watt (1979)

This is not just about a paper, but also about mentoring!  At the beginning of October 1977, I hesitantly knocked on the door of Professor Tony Dixon’s outer office in the School of Biological Sciences at the University of East Anglia, Norwich.  Tony was to become my PhD supervisor for the next three years and my friend and colleague for the next forty plus years, but until that day I had never met him, as my interview had been conducted entirely by telephone and in those pre-internet days, unless you had met someone at a conference you really only knew them by their papers and reputation.  I knew Tony because of his great little book, The Biology of Aphids which I had bought as an undergraduate in 1975, when I realised that aphids were really cool 😊 I told his secretary who I was and she directed me through to his office.  Tony looked up, said hello and asking me to follow him, took me down to the lab where I was to spend the next three years and introduced me to a tall, moustachioed Scotsman, Allan Watt, whom I was later to discover had a wicked sense of humour, and was to become not just a colleague and collaborator, but also a great friend, a friendship that continues to this day.  Tony’s introduction was roughly along the lines of “This is Allan, he’ll tell you what to do” and he did. Allan was just starting the final year of his PhD which was, like a number of us in Tony’s lab, on cereal aphids, in Allan’s case Sitobion avenae and Metopolphium dirhodum, the two major pests of cereals in the UK at the time.  My PhD was on a less abundant (in cereal crops), but equally problematic aphid, due to its ability to transmit Barley Yellow Dwarf Virus, the bird cherry-oat aphid Rhopalosiphum padi.  Having got my aphid cultures set up and done a couple of practice mini-experiments, I asked Allan what he was doing with his aphids.  He told me that he was looking at the effect of cereal growth stage on the survival and reproduction of his two aphid species and that the age of the plant had a significant effect on the aphids and that this varied between the two species, which he published a couple of years later (Watt, 1979).  Having been immersed in the cereal aphid literature for a couple of months, I knew that no one had done this for my aphid, and even then, being a great believer in “standing on the shoulders of giants” I figured that I could do the same for my aphid, but, in that never ending treadmill of adding novelty, also look at the effect of feeding position*. Allan’s advice and help stood me in good stead, and in due course I successfully published the results of my experiment (Leather & Dixon, 1981).

So, leaving aside me getting a publication as a result of Allan’s paper, how did this shake my World?  Well, first of all, it really drove home to me that plant phenological stage was incredibly important for insect-plant interactions and that unless you know the precise growth stage at which an interaction is happening it is difficult to compare other peoples’ results to yours and each other’s. As a result, it has led me as a reviewer and reader of papers, to be very scathing of phrases such as “ten-day old wheat plant”, “week old cabbage seedlings”, “young pea plant” (Leather, 2010).  It is deeply unhelpful for anyone wanting to repeat or compare similar work.  Just a few degrees difference in temperature over a week can move a plant from one phenological stage to another. There is no excuse for this type of sloppiness.

Two seven-day old wheat plants, same cultivar, same germination date, one reared at 20⁰C the other at 10⁰C. Growth stage 12 versus Growth stage 10 (Growth stages as described by Tottman & Makepeace, 1979).

The same two plants now fourteen day sold, GS 13 versus GS 12

It is not hard to find a solution.  The World has been blessed by the invention of the BBCH** system for coding plant phenological stages (Meier et al., 2009).  This system, which now exists for most major crop plants, including trees, means that there is no excuse for anyone to ever use the phrase “ten-day old plant” or similar wording. If by some chance, your plant does not yet have a BBCH description, either describe the growth stage that your plants are at in very precise terms or take the time to codify it yourself and submit it to a journal such as Annals of Applied Biology which has a long history of publishing such articles.

To be fair, before the BBCH system came into being, people had published descriptions of plant growth stages for some of the major crops, e.g. cereals (Feekes, 1941; Large, 1954), but they were not standardised, and in some cases, too broad-brush.  The stimulus for a standardised, decimal system of coding plant phenological stages was the publication of the Zadoks scale for cereals (Zadoks et al., 1974) and the illustrated follow-up a few years later (Tottman & Makepeace, 1979), the latter being the blueprint on which phenological growth stage papers are now based.

I look forward to the day when authors understand that a precise knowledge of plant growth stage is essential to understanding insect-plant interactions and I do NOT have to chide authors for not using the BBCH codification when I review their papers.

 

References

Feekes, W. (1941) De Tarwe en haar milieu. Vers. XVII Tech. Tarwe Comm. Groningen, 560-561.

Large, E.C. (1954) Growth stages in cereals. Plant Pathology, 3, 128-129.

Leather, S.R. (2010) Precise knowledge of plant growth stages enhances applied and pure research. Annals of Applied Biology, 157, 159-161.

Leather, S.R. & Dixon, A.F.G. (1981) The effect of cereal growth stage and feeding site on the reproductive activity of the bird cherry aphid Rhopalosiphum padi. Annals of Applied  Biology, 97, 135-141.

Meier, U., Bleiholder, H., Buhr, L., Feller, C., Hack, H., Hess, M., Lancashire, P.D., Schnock, U., Strauss, R., Vanden Boom, T., Weber, E. & Zwerger, P. (2009) The BBCH system to coding the phenological growth stages of plants – history and publications. Journal fur Kulturpflanzen, 61, S.41-52.

Tottman, D.R. & Makepeace, R.J. (1979) An explanation of the decimal code for the growth stage of cereals, with illustrations. Annals of Applied Biology, 93, 221-234.

Watt, A.D. (1979) The effect of cereal growth stages on the reproductive activity of Sitobion avenae and Metopolphium dirhodum. Annals of Applied Biology, 91, 147-157.

Watt, A.D. & Dixon, A.F.G. (1981) The effect of cereal growth stages and crowding of aphids on the induction of alatae in Sitobion avenae. Ecological Entomology, 6, 441-447.

Watt, A.D. & Wratten, S.D. (1984) The effects of growth stage in wheat on yield reductions caused by the rose grain aphid, Metopolophium dirhodum. Annals of Applied Biology, 104, 393-397.

Zadoks, J.C., Chang, T.T. & Konzak, C.F. (1974) A decimal code for the growth stages of cereals. Weed Research, 14, 415-421.

 

 

 

*

*Rhopaloisphum padi, in contrast to Sitobion avenae, is usually found on the lower stem and leaves of cereals.

**

The abbreviation BBCH derives from the names of the originally participating stakeholders: “Biologische Bundesanstalt, Bundessortenamt und CHemische Industrie”. Allegedly, the abbreviation is said to unofficially represent the four companies that initially sponsored its development; Bayer, BASF, Ciba-Geigy, and Hoechst.

 

 

Leave a comment

Filed under Ten Papers That Shook My World

Not all aphids live on leaves

I haven’t written about aphids for a while, so I thought I would indulge myself and tell you about a few of my favourite aphids.  Most people’s perceptions of aphids (assuming that they know what  aphids are of course) is that they live on leaves.  They will I think, also possibly know that they are usually found on the undersides of leaves, although I may be assuming too much here.  In fact, many species of aphid do not live on leaves; a number of species feed on shoots, twigs and branches and some actually feed on the main trunks of trees.  Yet other species live on the roots of trees and herbaceous plants, such as the apple-grass aphid, Rhopalosiphum insertum which can be a pest of apples and cereals, feeding on the leaves and buds of apples and the roots of grasses and cereals.   Another root-feeding aphid that is a double pest, is Pachypappa tremulae, the spruce root aphid, which host alternates between the aerial parts of aspen trees and the roots of Norway spruce; easily visible when infesting the roots of young potted plants due to the presence of white waxy tufts on its rear end.

Some aphids not only live underground feeding on roots, but are entirely dependent on being farmed by ants e.g.  Tetraneura ulmi, which host-alternates between elm and grass roots, and  Forda formicaria, which host-alternates between Pistachio trees and grass roots.

Forda_formicaria_hirsuta_root_aphid_03-03-13_3

http://www.aphotofauna.com/images/bugs_homoptera/bug_forda_formicaria_hirsuta_root_aphid_03-03-13_3.jpg

Both these aphids are looked after or ‘farmed’ by the yellow meadow ant Lasius flavus in exchange for donations of honeydew.

Lasius%20flavus%202

These two aphid species, along with a number of others, have an enlarged anal plate surrounded by special hairs that form the so-called trophobiotic organ.  This acts as a storage device that allows the aphid to accumulate honeydew ready for the ants to remove.  Those aphids that have a more casual (facultative) relationship with ants, do not have this organ which is the basis of this remarkable mutualism.

Another aphid that is farmed by ants, but in a somewhat different way, is the rather larger rose root aphid, Maculolachnus submacaula, which as its name suggests, feeds on rose roots.  In this case, the ants allow the aphids above ground but only in an ant tunnel, similar to those produced by termites when they are infesting a building.  I have only ever been lucky enough to see this aphid once, some 35 years ago in Norwich when I was doing my PhD and noticed things that looked like termite trails running up the main stem of one of my rose bushes.  On breaking them open, well I am a curious entomologist, I found to my surprise not only ants but large brown aphids.

Maculolachnus submacula nest

http://jardiweb-floralbum.forumsactifs.com/t1797-colonie-de-pucerons

for a better view of the aphid see http://www.afripics.co.za/home/products/product.php?ProductID=1301564582

But of course the really spectacular ones are those that feed on branches of trees such as the giant willow aphid Tuberolachnus salignus (famous for its sharks fin) and those from the genus Stomaphis which feed through the bark of trees such as oak and

Tuberolachnus

sycamore and are possessed of truly enormous mouthparts such as those of Stomaphis aceris which feeds on sycamore

Stomaphis query aceris

This one, despite its enormous mouthparts, is quite difficult to find as it hides underneath the bark, but luckily it is ant attended so if you see ants scurrying around on the bark of sycamore and disappearing underneath loose flaking bits, it is a good bet that if you gently lever off the loose bark you will find yourself in the presence of this weird-looking creature.

The more I learn about aphids the more I find to marvel at.  Aphids really are remarkable and we know so little about so many of them and their weird and wonderful life styles.

Useful References

Blackman, R.L. & Eastop, V.F. (19 94) Aphids on the World’s TreesAn  Identification and Information Guide.  CABI Publishing. http://www.aphidsonworldsplants.info/index.htm

Evenhuis, H.H. (1968)  The natural control of the apple grass aphid,  Rhopalosiphum insertum, with remarks on the control of apple aphids in general in The Netherlands. Netherlands Journal of Plant Pathology, 74, 106-117  http://link.springer.com/article/10.1007/BF02309501#page-1

Farrell, J.A. & Stufkens, M.W. (1989) Flight activity and cereal host relationships of Rhopalosiphum spp. (Homoptera: Aphididae) in Canterbury New Zealand Journal of Journal of Crop and Horticultural Science, 17, 1-7  http://www.tandfonline.com/doi/abs/10.1080/01140671.1989.10428003

Ivens, A.B.F., Kronauer, D.J.C., Pen, I., Weissing, F.J. & Boomsma, J.J. (2012)  Ants farm subterranean aphids mostly in single clone groups – an example of prudent husbandry for carbohydrates and proteins?  BMC Evolutionary Biology, 12:106 http://link.springer.com/article/10.1186%2F1471-2148-12-106

5 Comments

Filed under Aphidology, Aphids