Tag Archives: mimicry

Arthropod orchids – who’s fooling who?

A few weeks ago I read the first volume of Jocelyn Brooke’s Orchid trilogy, The Military Orchid. I have never been a great fan of orchids, my main experience of them being as ornamental house plants in which context I have always found them ugly, ungainly and obtrusive.

My colleague Lucy’s orchid ‘brightening up’ our communal office kitchen area

‘Artistically displayed’ for sale by an on-line florist – still just as ugly

Jocelyn Brooke’s account of his search for the Military Orchid was however a bit of a revelation.  His obsession with the eponymous orchid reminded me of how I quite liked seeing the first emerging spikes of the common spotted orchid, Dactylorhiza fuchsii appearing in Heronsbrook Meadow at Silwood Park as I returned from my lunchtime run.  A little bit later Jeff Ollerton posted an interesting article about orchid pollination myths and this got me thinking about the common names of our native UK orchids, especially those named after arthropods.

It turns out that there are fewer than I thought; Bee, some varieties of which seem to be called the wasp orchid, the Fly, Lesser butterfly, Greater butterfly, Early spider and Late spider orchid being the lot.  My self-imposed mission was to first find a suitable photograph of each species to see if it did look like its namesake and secondly to identify the main pollinators.  Or to put it another way, exactly what are they mimicking and what or who are they really fooling?  Orchids generally speaking are honest brokers, providing nectar as a resource for pollination services (Nilsson, 1992).  About a quarter of orchid species are however frauds or cheats (Nilsson, 1992), either pretending to be a food source or a receptive female insect, nutritive deceptive or sexually (reproductive) deceptive as the jargon has it (Dafni, 1984).  Ophrys orchids are sexually deceptive (Nilsson 1992).

The Bee Orchid, Ophrys apifera, is pollinated by a solitary mining bee, Eucera longicornis  (Kullenberg, 1950) belonging to a group commonly known as long horned bees, which in the UK is rather uncommon meaning that the Bee Orchid is generally self-pollinated.

The Bee Orchid, Ophrys apiferahttps://thmcf.files.wordpress.com/2013/07/bee-orchid-imc-3702.jpg with pollinator Eucera longicornis http://www.bwars.com/bee/apidae/eucera-longicornis

If you look at the female bee, which is what we suppose the flower is mimicking, you can just about convince yourself that there is a slight resemblance between the two.  Insects of course do not see things the same way humans do (Döring et al., 2012) so what we think is almost certainly irrelevant.  That said, it doesn’t actually have to be a particularly good visual mimic for the insects either, as it is the smell that really matters and as long as the flower is the right shape to enable the deceived male to copulate in such a way that the flower is fertilized that is all that matters.   To quote Dafni (1984) “The olfactory specificity allows a high degree of morphological variability because the selective pressures leading to uniformity-as a means for better recognition-are relaxed. When odors become the main means of attraction, they efficiently serve as isolating agents among closely related species

The fly orchid, Ophrys insectiflora, is also sexually deceptive, but despite its common name is pollinated by digger wasps and bees (Kullenberg, 1950; Wolff 1950).

Ophrys insectifera   Fly orchid  By Jörg Hempel, CC BY-SA 3.0 de, https://commons.wikimedia.org/w/index.php?curid=32968796  with pollinator Argogorytes mystaceus (formerly Gorytes) http://www.bwars.com/category/taxonomic-hierarchy/wasp/crabronidae/nyssoninae/gorytes

Oddly, despite being sexually deceptive it does, at least in my opinion, resemble its pollinators fairly well.

Next up (alphabetically), we have the Lesser Butterfly Orchid, Planthera bifolia, which despite its name is pollinated by night-flying hawk moths,

 

The Lesser Butterfly Orchid, Planthera bifolia.  By © Hans Hillewaert, CC BY-SA 4.0, https://commons.wikimedia.org/w/index.php?curid=4112191 and the two leading pollinators Hyloicus pinastri and Deilephila elpenor.

most commonly by the Pine Hawk Moth, Hyloicus pinastri and the Elephant Hawk Moth, Deilephila elpenor  (Nilsson (1983). These orchids provide a nectar reward, and attract their pollinators by producing a strong scent (Nilsson, 1978) easily detected by humans even at a distance (Tollsten & Bergström, 1989).  As an added extra, the flowers are very light-green and also highly light-reflecting, giving the moths a visual as well as an olfactory signal (Nilsson, 1978).  In terms of shape the flower more closely resembles H. pinastri.

The closely related Greater Butterfly Orchid, Planthera chlorantha is also pollinated by night-flying moths, the two Elephant hawk moths  Deiliphila porcellus and D.elpenor, 

Platanthera chlorantha,  The Greater Butterfly  Orchid https://c1.staticflickr.com/8/7795/17960863138_721033c527_b.jpg with hawk moth and Noctuid pollinators.

but mainly by Noctuid moths, most commonly, Apame furva (The Confused) and  A. monoglypha (the Dark Arches) Nilsson (1983).  Although recent video evidence has shown that the Pine Hawk moth also pollinates it (Steen, 2012).  Like the Lesser Butterfly Orchid, the flower only vaguely resembles its pollinators.  The chemicals responsible for the characteristic and intense fragrances of these two closely related orchids differ between the species and is probable that they are linked to the preferences of the different pollinator species (Nilsson, 1978).

Despite its name and suggested resemblance to its namesake, the Early Spider Orchid, Ophrys sphegodes is pollinated by a solitary bee,

Ophrys sphegodes, The Early Spider Orchid

https://species.wikimedia.org/wiki/Ophrys_sphegodes_subsp._sphegodes#/media/File:Ophrys_sphegodes_Taubergie%C3%9Fen_22.jpg

Andrena nigroaenea (Schiestl et al. 2000).  The scent of the nectarless flower, closely resembles the female sex pheromone of the bee and fools the male into ‘mating’ with it (Schiestl et al., 2000).  If you allow your imagination to run riot you could possibly just about see the flower as a giant female bee which might act as an extra stimulus for an excited male bee (Gaskett, 2011).

The final arthropod orchid is the Late Spider, Ophrys fuciflora; do be careful how you pronounce it, a soft c might be advisable 🙂

Ophrys fuciflora, the Late Spider orchid and two of its documented pollinators, Eucera longicornis (originally tuberculata) and Phyllopertha horticola.  Orchid Photo by © Pieter C. Brouwer and his Photo Website

As with all Ophrys orchids, they are sexually deceptive and attract male insects to their nectar-free, but highly scented flowers, with the promise of a good time Vereecken et al., 2011).  Most pollination is by solitary bees (Kullenberg, 1950) although the Garden Chafer, Phyllopertha horticola has been recorded as pollinating it in northern France (Tyteca et al., 2006).  Again both pollinators could be said to resemble the flowers to some extent

That concludes my tour of UK arthropod orchids.  Having learnt a lot about other orchids in the last couple of weeks while researching this article it seemed a shame to waste it.  So, as an added bonus, I’m going to finish with a few imaginatively named orchids, the names of which do not refer to their pollinators but rather to the imagination of their human namers.

Orchis anthropophora, The Man Orchid.  Photo by Erwin Meier

This not usually pollinated by sexually-deceived humans but by two beetles, Cantharis rustica (soldier beetle) and Cidnopus pilosus (click beetle) and also by two species of sawfly Tenthredopsis sp. and Arge thoracia (Schatz, 2006).

Orchis simia, The Monkey Orchid. Photo Dimìtar Nàydenov

Again, as with the Man Orchid, the Monkey Orchid, is not pollinated by cruelly deceived anthropoids.  There are, as far as I can discover, only a few confirmed pollinators of O. simia.  They include the beetle C. pillosus, the moth Hemaris fuciformis and some hymenopterans such as honeybees (Schatz, 2006).  According to PlantLife, hybrids of the Man Orchid and Monkey Orchid are called the Missing Link Orchid.

My fellow blogger Jeff Ollerton and his colleagues (Waser et al., 1996), point out that pollination systems are not as specialist as many might think, and even in sexually-deceptive orchids that use pheromone mimics, many of their pollinators can get ‘confused’ and pollinate closely related orchid species.  Hence the existence of what are termed ‘natural hybrids’ such as the Missing Link Orchid and the interesting hybrid between the Fly Orchid and the Woodcock Orchid pictured below.

The hybrid, Fly x Woodcock  Orchid.  Photo Karen Woolley‏ @Wildwingsand

It looks like a belligerent penguin to me, but is of course pollinated by insects.

Often regarded as one of the most bizarrely flowered orchids is the Flying Duck Orchid, Caleana major from Australia.

Flying duck orchid Caleana major (from Australia) sawfly pollinated (Adams & Lawson, 1993).

I was intrigued to notice what appears to be a Cantharid beetle, species of which are known to pollinate other orchids (Schatz, 2006), lurking in the background. There are a number of Cantharids noted as being pollinators in Australia, some of which have been recorded pollinating orchids, although not specifically on Calaena (Armstrong, 1979) so this may be an overlooked pollinator, just waiting to be confirmed by a dedicated pollinator biologist or orchidologist.  There is also, if you wondered, a Small Duck Orchid, Paracaleana minor.

Who would have thought that reading a biography would have started me off on such an interesting paper hunt?  Perhaps the most interesting new bit of information I discovered was that male orchid bees although they attract females with scents, do not produce their own pheromones but collect flower volatiles which they mix with volatiles from other sources like fungi, plant sap and resins (Arriaga-Osnaya et al., 2017).  They use these ‘perfumes’ as part of their competitive courtship behaviour to attract females; the best perfumier wins the lady J

And then you have Dracula vampira….

Dracula vampira (Vampire orchid) – only found in Ecuador (Photo: Eric Hunt, licensed under CC by 3.0).© Eric Hunt.  I hasten to add this is not pollinated by vampires, bats or otherwise.

 

But to finish, here is the one that started it all…

The one that started it all, The Military Orchid, Orchis militaris  https://upload.wikimedia.org/wikipedia/commons/d/d4/Orchis_militaris_110503a.jpg

 

Acknowledgements

Many thanks to Manu Saunders over at Ecology is Not a Dirty Word for sending me a key reference and also to her and Jeff Ollerton for casting critical ‘pre-publication’ eyes over this post.

References

Armstrong, J.A. (1979) Biotic pollination mechanisms in the Australian flora — a review.  New Zealand Journal of Botany, 17, 467-508.

Adams, P.B. & Lawson, S.D. (1993) Pollination in Australian orchids: A critical assessment of the literature 1882-1992.  Australian Journal of Botany, 41, 553-575.

Arriaga-Osnaya, B.J., Contreras-Garduño, J., Espinosa-García, F.J. García-Rodríguez, Y.M.,  Moreno-García, M., Lanz-Mendoza, H., Godínez-Álvarez, H., & Cueva del Castillo, R. (2016) Are body size and volatile blends honest signals in orchid bees? Ecology & Evolution, 7, 3037–3045.

Dafni, A. (1984) Mimicry and deception in pollination.  Annual Review of Ecology & Systematics, 15, 259-278.

Döring, T.F., Skellern, M., Watts, N., & Cook, S.M. (2012) Colour choice behaviour in the pollen beetle Meligethes aeneus (Coleoptera: Nitulidae). Physiological Entomology, 37, 360-368.

Gaskett, A.C. (2011) Orchid pollination by sexual deception: pollinator perspectives. Biological Reviews, 86, 33-75.

Kullenberg, B. (1950) Investigations on the pollination of Ophrys species. Oikos, 2, 1-19.

Nilsson, L.A. (1978) Pollination ecology and adaptation in Platanthera chlorantha (Orchidaceae).  Botaniska Notiser, 131, 35-51.

Nilsson, L.A. (1983) Processes of isolation and introgressive interplay between Platanthera bifolia (L.) Rich and P. chlorantha (Custer) Reichb. (Orchidaceae). Botanical Journal of the Linnean Society, 87, 325-350.

Schatz, B. (2006)  Fine scale distribution of pollinator explains the occurrence of the natural orchid hybrid xOrchis bergoniiEcoscience, 13, 111-118.

Schiestl, F.P., Ayasse, M., Pauklus, H.F., Löfstedt, C., Hansson, B.S., Ibarra, F. & Francke, W. (2000) Sex pheromone mimicry in the eraly spider orchid (Ophrys sphegodes): patterns of hydrocarbons as the key mechanism for pollination by sexual deception.  Journal of Comparative Physiology A, 186, 567-574.

Steen, R. (2012) Pollination of Platanthera chlorantha (Orchidaceae): new video registration of a hawkmoth (Sphingidae). Nordic Journal of Botany, 30, 623-626.

Tollsten, L. & Bergström, J. (1989) variation and post-pollination changes in floral odours released by Platanthera chlorantha (Orchidaceae). Nordic Journal of Botany, 9, 359-362.

Tyteca, D., Rois, A.S. & Vereecken, N.J. (2006) Observations on the pollination of Oprys fuciflora by pseudo-copulation males of Phyllopertha horticola in northern France. Journal Europäischer Orchideen, 38, 203-214.

Vereecken, N.J., Streinzer, M., Ayasse, M., Spaethe, J., Paulus, H.F., Stökl, J., Cortis, P. & Schiestl, F.P. (2011) Integrating past and present studies on Ophrys pollination – a comment on Bradshaw et al. Botanical Journal of the Linnean Society, 165, 329-335.

Waser , N.M., Chittka, L., Price, M.V., Williams, N.M. & Ollerton, J. (1996) Generalization in pollination systems, and why it matters. Ecology, 77, 1043-1060.

Wolf, T. (1950) Pollination and fertilization of the Fly Ophrys, Ophrys Insectifera L. in Allindelille Fredskov, Denmark. Oikos, 2, 20-59.

 

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Butterflies Galore – visual treats from two very different books

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I have written a lot of book reviews over the last thirty years or so; initially for mainstream scientific journals; those were the days when journal editors had never heard of impact factors and space was specifically set aside for such articles. And latterly, for the in-house member’s bulletins of learned societies such as Antenna; the excellent and very glossy publication of the Royal Entomological Society.  Book reviews are generally a bit of a chore, especially if the book in question is an edited volume, but busy academics can sometimes be persuaded to take a review on if they think that the book (the only payment you receive is a free copy) will justify the effort.  Occasionally one gets the chance, or feels the urge, to use a book review as a means of getting a particular message across to a wider audience.  I once managed to have one of my ‘on the importance of entomology’ rants published in Trends in Ecology & Evolution (Leather, 2008) using this route.  Up until now however, unless you count my somewhat tongue-in-cheek review of Anna Aphid, I have not used my blog in this way.   This is, however, about to change.

At the end of November last year (2015), I received an email from Caroline Young of Firefly Books who wondered if I would like to review a new entry to their catalogue, Butterflies, by Ronald Orenstein and Thomas Marent.   It was such a flattering email that I succumbed to her blandishments, hence this first official book review on my site.  To retain some scientific integrity however, I decided that I would do a comparative review.  Fortuitously, it just so happened, that I had to hand another book about butterflies; one that I had semi-promised to review for the Royal Entomological Society (Howse, 2014), but until now, had never got around to doing.  In one fell swoop I was thus able to salve my conscience and do two favours 🙂

When reviewing a book I have a little mental list of questions that I answer as I read it.

  1. Would I buy it?
  2. Would I recommend a colleague to buy it?
  3. Would I recommend it to students as worth buying?
  4. Would I ask the library to buy it?
  5. Would I recommend it to anyone to buy it?

All these have the same subsidiary questions attached to them; If not why not, if yes, why?

First, Butterflies, billed by the publisher’s blurb as a “visual feast that showcases the beauty and mystery of butterfly and moth species from around the globe”.  A good place to start with a book review is with a summary of the contents and the aim(s) of the author(s).  There are eleven named chapters in total, with a thirty page introductory chapter, aptly titled Introducing butterflies.  This chapter, which like all the others, is beautifully illustrated with stunning photographs, briefly covers the main features of butterfly biology and ecology, from evolution, taxonomy, flight, mimicry, courtship, oviposition, development, feeding, predation, migration and concludes with climate change and conservation.  There is no overall ‘mission statement’ per se, but towards the end of the introduction the authors write “We need to know more and to do better. In many parts of the world, butterflies are disappearing at a rapid rate.  We need to understand what is happening to them, and why, if we are to stop or reverse their decline.  We need to create space for butterflies.”

From this I take it that the purpose of the book is to inspire adult non-entomologists to take an interest in butterflies in general and to create habitats for them in their gardens. I also think that there other aim is to inspire the younger generation to become involved with butterfly conservation either professionally or as an extra-mural interest.  The twelve chapters that follow the introductory piece are first, taxonomically based, e.g. Swallowtails, Skippers, Whites and then to do with their biology and ecology, covering topics such as wings, life history, diet, mimicry etc.  The last chapter is about those too-often overlooked Lepidoptera, the moths.  Each chapter is dominated by the beautiful photographs, each of which is accompanied by a succinct pen sketch giving a brief description of the species shown and some useful nuggets of information about the distribution, taxonomic position of the species and something about their biology.  Some of these nuggets were new to me, perhaps not surprisingly, as I am not primarily a lepidopterist 🙂

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I was, for example, interested and intrigued by the suggestion that eggs of The Map, Araschnia levana are mimics of the flowers  of its larval host plant, nettle (Urtica spp.).

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http://bioweb.uwlax.edu/bio203/2011/homolka_kail/reproduction.htm   ttps://commons.wikimedia.org/wiki/File:Urtica_dioica.JPG

In fact I was so intrigued that I felt the need to test it out by searching for photographs of nettle flowers. These shown are the closest I could find that come close to matching the eggs and so to a certain extent I remain unconvinced.  I will however, leave that up to you to decide for yourselves.

In summary, this book is as advertised, “a visual feast that showcases the beauty and mystery of butterfly and moth species from around the globe.”  It is not a text-book, nor is it an exhaustive pictorial catalogue, you could not use it as an identification guide. It does however, give a good and accessible overview of some basic butterfly biology and ecology and also great factoids to store away for use at an opportune moment.  So the bottom line:

  1. Would I buy it?   – No, in my opinion, it does not contain enough entomological detail for me as a professional to justify the $45 price tag.
  2. Would I recommend a colleague to buy it? Probably not for the same reason as above.
  3. Would I recommend it to students as worth buying? Again, probably not, but I might suggest that they put it on their Christmas or birthday lists.
  4. Would I ask the library to buy it? Yes, I think that it contains enough useful information to make it attractive to a non-specialist student reader interested in an easy to understand book with enough useful essay material in it.

and finally, would I recommend it to anyone else to buy it,? Yes it is a nice book, albeit of the coffee table variety, but in my opinion at the upper end of that market and anything that might spark an interest in entomology amongst the as yet unconverted, can only be a good thing.

And now, Philip Howse’s book, Seeing Butterflies, which is subtitled, New Perspectives on Colour, Patterns and Mimicry.  The publisher’s blurb in this instance states “See living butterflies and moths through new eyes through Philip Howse’s fascinating text and superb imagery….This new way of looking at these beautiful and iconic images will inform and inspire nature-lovers, photographers artists and scientists.”  Some major claims are being made here, implying that this is a serious book aimed at specialists, yet with the potential to appeal to a much wider readership.  Does it live up to these claims?

As with Butterflies, we are presented with twelve beautifully illustrated chapters.  Here though, with a chapter entitled, Seeing: Illusion, deceit and survival, we know from the start that this book is about vision, about visibility and invisibility and about optical illusions.  Chapter two continues this theme, being about defence and illusion while Chapter three examines the evolution of butterflies and mimicry.  The remaining chapters, as with Butterflies, are taxonomically based and examine the very varied visual defence mechanisms exhibited across the various butterfly families.  The photographs may not be as professional, as many or as stunning as those in Butterflies, but the science is much stronger, yet still very accessible to the lay reader.  There is also much more natural history, although again, this is not a book that would be useful for identification purposes.  On the other hand there are some marvellous nuggets and factoids, with which to regale friends, students and anyone else that you can catch.   One that sticks in my mind particularly, is that apparently the small tortoiseshell, Aglais urticae was once known as the ‘devil butterfly’ in Scotland. Philip speculates that this might be because it “comes out of the darkness of winter and hibernation, marked in red and black”.  As with Butterflies there were numerous factoids that intrigued and interested me.  In particular Philip’s claims for the eyed hawkmoth, Smerinthus ocellata, that he feels can impersonate a bracket fungus, a pile of dead leaves and a fox-like animal!

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The first two I am quite happy about, but the third suggestion seems to need quite a stretch of the imagination 🙂

There is more of the author apparent in Seeing Butterflies than in Butterflies; Philip recalls childhood memories, and other personal experiences to illustrate the points that he makes and this gives the book a very user-friendly feel that is, to a certain extent, lacking in Butterflies. I also think that on the whole, the book manages to live up the somewhat over-hyped blurb.

And so the bottom line:

  1. Would I buy it? – Yes I would, very nicely priced, well-written and enough science to keep me happy and interested.
  2. Would I recommend a colleague to buy it? Yes, even a non-entomological colleague would be likely to find it worth the money.
  3. Would I recommend it to students as worth buying? Yes, I would certainly suggest it to my PhD students and MSc Entomology students, but probably not to undergraduates although I would definitely suggest that they put it on their Christmas and/or birthday lists.
  4. Would I ask the library to buy it? Yes, both as a recommended book for the entomologists and it contains enough useful information to make it attractive to a non-specialist student reader interested in an easy to understand book with useful essay material in it.

 and finally, would I recommend it to anyone else to buy it,? Yes it is a nice book and should appeal to anyone who has a genuine interest in the natural world.

 So there you have it, my first official ‘blog’ book review. There may be more to come, not necessarily commissioned ones, but just books that take my fancy, but if there are any publishers, or authors out there who think that I might like to review one of their books, feel free to contact me to discuss it.

 

References

Howse, P. (2014) Seeing Butterflies, Papdakis Publisher, Winterbourne, UK.  Paperback, 176 pp, £16.99 ISBN-13: 978-1-906506-46-9

Leather, S.R. (2008). Conservation entomology in crisis. Trends in Ecology & Evolution, 123, 184-185

Orenstein, R. & Marent, T. (2015) Butterflies, Firefly Books, Buffalo, USA. Hardback, 288 pp, $45 ISBN-13: 978-1-77085-580-0; ISBN-10: 1-77085-580-7

 

Postscript

For anyone seriously interested in writing academic book reviews I can recommend this site by Dr Perpetua Turner https://peptalkecology.wordpress.com/2016/01/13/writing-an-academic-book-review/

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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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