Tag Archives: pine beauty moth

When frustration becomes serendipitous – My second most cited paper

For most of the 1980s and the early 1990s I worked for the UK Forestry Commission as a research and advisory entomologist. As a civil servant I was subjected to a lot more rules than I am now as a university academic. The most frustrating set of rules in my mind, were those associated with publishing papers. The initial consultation with a statistician before your experiment was planned and any subsequent collaboration with the analysis was very sensible, and I had no problems with that part of the process at all. Our statisticians were very good in that they helped you decide the analysis but expected you to learn GenStat (the Forestry Commission standard statistics programme) and do it yourself unless you were really stuck.

The next bit was the frustrating part. When it came to writing papers you first submitted your paper to your line manager. They then read your paper, very frustrating indeed for me, as my immediate boss considered papers a very low priority and it could be several months before he got around to passing it back with comments and suggestions. Then it was passed to a member of one of the other department such as silviculture, tree breeding or pathology for them to read and make comments. The idea behind this being that it helped make the paper accessible to a wide audience, again a good idea. The problem at this stage was that once again your paper was likely to be a low priority, so yet more delay. Once that was done you then had to submit your paper to the Chief Research Office for him to read and comment on, so once again yet more delay. This meant that quite often it was a year before you actually were able to submit your paper to a journal, which could be deeply frustrating to say the least.

Frustrated

In 1986 a new journal to be published by the British Ecological Society was announced, Functional Ecology. In those days, the dreaded Impact Factors had not yet raised their ugly heads, and one tended to publish in journals relevant to your discipline, or, as in this case, the fancy took you.  I thought it would be cool to publish in the first issue of the first volume of this new journal.  I therefore set to work, with the help of one of our statisticians to produce a paper about life history parameters of the pine beauty moth, from a more ecological point of view and not from the more applied view-point of it as a forest pest (my job remit). I was very proud of the paper and confess to having got somewhat carried away in the discussion, so much so, that it was suggested by all who read it in the very lengthy internal appraisal process, that most of the discussion should be cut as being too far away from the main story. As the process had taken so long already I decided to go with the flow and eventually submitted my paper about a year after first writing it, incidentally giving my statistician a co-authorship. It was accepted and did indeed appear in the first volume of Functional Ecology, albeit the last of the year (Leather & Burnand, 1987)! It has to date (14th October 2015) being cited 53 times, by no means a disgrace, but certainly not my second-most cited paper.

I mentioned earlier that I was really proud of my discussion and I decided that I was going to publish it regardless. I reworked it slightly and submitted it to Oikos as a Forum piece, taking the calculated risk of not submitting it through the official Forestry Commission system. My reasoning was, that a), it was unlikely to be read by anyone in the Forestry Commission, being a very ecological journal, and b), if challenged I would say that it had already been seen by the powers that be, albeit not officially. To my relief it was accepted as is (Leather, 1988) and my immediate boss never mentioned it. To my surprise and delight this is now my second-most cited paper, having so far acquired 207 citations and still picks up a reasonable number of cites every year. I guess that I should actually be grateful to all those internal referees who insisted that I cut my discussion down so drastically.

References

Leather, S.R. (1988) Size, reproductive potential and fecundity in insects: Things aren’t as simple as they seem. Oikos, 51, 386-389.

Leather, S.R. & Burnand, A.C. (1987) Factors affecting life-history parameters of the pine beauty moth, Panolis flammea (D&S): the hidden costs of reproduction. Functional Ecology, 1, 331-338.

 

Post script

In case you wondered, my most cited paper is an Annual Review paper, written with one of my former PhD students, Caroline Awmack, and now has almost a thousand citations (994 as of today).

Reference

Awmack, C. S. &Leather, S. R. (2002). Host plant quality and fecundity in herbivorous insects. Annual Review of Entomology 47, 817-844.

 

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Insect egg mimics – plant parts that pretend to be insect eggs

Back in the 1980s I was a forest entomologist working for the UK Forestry Commission at their Northern Research Station based just outside Edinburgh.  I was working on two important pests of Lodgepole pine (Pinus contorta), the pine beauty moth, Panolis flammea and the European pine sawfly, Neodiprion sertifer.  The pine beauty moth lays its eggs in short rows on the upper surface of pine needles in late spring/early summer.

Panolis eggs

Eggs of the pine beauty moth, Panolis flammea  (Image courtesy of Stanislaw Kinelski, Bugwood.org http://www.invasive.org/browse/detail.cfm?imgnum=1258002).

They are pale yellow when first laid and gradually darken as they mature becoming a deep violet colour just before they hatch.  The eggs of Neodiprion sertifer are also laid on the upper part of the pine needles, but are ‘injected’ just under the cuticle of the needle.  After a few days a small necrotic patch develops at the oviposition site.

Neodiprion eggs

Eggs of the European pine sawfly, Neodiprion sertifer (image courtesy of A. Steven Munson, USDA Forest Service, Bugwood.org http://www.forestryimages.org/browse/detail.cfm?imgnum=1470178)

Spring field work for me was several days of rather tedious egg counting and as I scrutinised hundreds of pine needles, I noticed that some of the needles had little flecks or balls of resin on them,

Resin flecks

Resin flecks on bristlecone pine, Pinus arsitata – often confused with scale insect infestations (Photo by Hans G. Oberlack via Wikipedia).

which were, especially on gloomy days in the depths of the forest, quite easy to confuse with pine beauty moth eggs.  Other needles had discoloured areas that looked like pine sawfly eggs or also a bit like pine beauty moth eggs, depending on how they were arranged.

Egg mimics

Possible insect egg mimics on pine needles

Long days working alone in a forest allow one the time to think and it occurred to me one day that if I was being fooled by these ‘pseudo eggs’ then perhaps egg-laying pine beauty moths and pine sawflies might also be getting confused and avoiding laying eggs on these apparently already infested needles.   I wondered if there was any evidence to support my far-fetched hypothesis and to my delight found a paper by (Williams & Gilbert, 1981) that demonstrated quite convincingly that passion-fruit vines, produce structures resembling eggs of Heliconius butterflies and that these deter them from laying eggs on them.

Egg mimics 2

Egg mimics on passion flower leaf – Photo by Lawrence Gilbert http://plantmimicrybz2820.blogspot.co.uk/2015/04/the-passiflora-genus.html

I also found papers that showed that other Lepidoptera (Rothschild & Schoonhoven, 1977; Nomakuchi et al., 2001) and beetles (Mappes & Mäkelä, 1993), are able to discriminate between leaves that already have eggs laid on them and avoid laying more eggs on those leaves, thus reducing larval completion.

Although I never formally checked it, I got the impression that needles bearing ‘egg mimics’ had fewer pine beauty moth eggs or pine sawfly eggs laid on them than those without.  Another question that could be easily looked at is whether pine trees in areas that have had outbreaks have more speckled needles than those in non-outbreak areas.  I always meant to do some formal sampling and a proper experiment to back up my feelings, but never found the time to do it.  I am pretty certain that I am unlikely to get round to doing this in the near future (if ever), but I would like to know if this is indeed another example of  a plant mimicking insect eggs.  I would be very happy indeed if any of you feel like testing my hypothesis and look forward to seeing the results in print.

 

References

MacDougal, J.M. (2003)  Passiflora boenderi (Passifloraceae): a new egg mimic passionflower from Costa Rica.  Novon, 13, 454-458

Mappes. J. & Mäkelä, I. (1993)  Egg and larval load assessment and its influence on oviposition behaviour of the leaf beetle Galerucella nymphaeae.  Oecologia, 93, 38-41

Nomakuchi, S., Masumoto, T., Sawada, K., Sunahra, T., Itakura, N. & Suzuki, N. (2001) Possible Age-Dependent Variation in Egg-Loaded Host Selectivity of the Pierid Butterfly, Anthocharis scolymus (Lepidoptera: Pieridae): A Field Observation .  Journal of Insect Behavior, 14, 451-458.

Rothschild, M. & Schoonhoven, L.M. (1977) Assessment of egg load by Pieris brassicae (Lepidoptera: Pieridae). Nature, 266, 352-355.

Williams, K.S. & Gilbert, L.E. (1981) Insects as selective agents on plant vegetative morphology: egg mimicry reduces egg laying by butterflies. Science, 212, 467-469.

 

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