Tag Archives: Hawaii

Meat eating moths

This post is dedicated with thanks to Entomology Uncensored which gave me the idea for this post.

Unless you believe that the Very Hungry Caterpillar’s diet is truly representative of what a lepidopteran larva eats, you will, if asked, almost certainly answer that caterpillars eat plants and that the adults, if they do feed, do so on nectar. Although this is true for the majority of Lepidoptera, there are a couple of exceptions that have opted for a very different life style. Some of you may already now be saying to yourselves, “Aha what about the clothes moth? That doesn’t eat plants, it eats clothes doesn’t it?”, and you would be right. The larvae of Tinea pellionella, the Case Bearing Clothes Moth, are not plant eaters, they make a living eating wool, fur and feathers among other keratinous* delicacies (Cheema, 1956).

Tinea pellionella – clearly demonstrating why it is called the case-bearing clothes moth

There are some moth species that have gone a step further in adopting an animal-based diet, feeding directly on living animals and not on their cast-off skins and horns. In 1879 the American entomologist John Comstock (1849-1931) while studying a colony of the cottony maple scale Pulvinaria innumerabilis, was one day surprised to find a caterpillar busily eating his study organisms.  Rather than losing his temper and killing the caterpillar, he reared it through to adulthood and realised that this was a species new to science, which he named Dakruma coccidivora (Constock, 1979), now renamed Laetilia coccidivora and recognised as a useful biological control agent (e.g. Goeden et al., 1967; Mifsud, 1997; Cruz-Rodriguez et al., 2016).  Perhaps it had evaded being spotted by less keen-eyed entomologists from its habit of living underneath the scale insects it eats (Howard, 1895).

The hidden life style of Laetilia coccidivora as described by Howard (1895)

Laetilia coccidivora busy eating prickly pear scale insects

Less deadly to its host, but no less of a carnivore, is the moth Epipomponia nawai.  This, and all the other members of its family, thirty-two in total, are all ectoparasites of Hemiptera, especially cicadas and planthoppers (Jeon et al., 2002).  The larvae attach themselves to the abdomen of their host and feed on the juicy flesh underneath the cuticle.  Once ready to pupate they spin a silk thread, drop off their host and spin a cocoon on the bark of the tree their host has fed on (Liu et al., 2018).  The adults do not fed and only live long enough to mate and lay eggs.  For those of you who love a mystery, no-one knows how the moth larvae find their cicada hosts. One possibility is that they might use the cicada song as a cue but this has, so far, not been proven (Liu et al., 2018).

Larva of Epipomponia nawai parasitizing an adult cicada (Liu et al., 2018).

An even more striking example of predatory behaviour in moth larvae is that shown by members of an otherwise herbivorous Genus of Geometrid (looper) moths, Eupithecia.  The Eupithecia have a worldwide distribution, but in Hawaii, all but two of the species are ambush predators Montgomery, 1983).  The caterpillars show typical looper behaviour, remaining motionless pretending to be a twig or leaf, depending on their colour.  When a potential prey item bumps into the back of the caterpillar it rears backwards and catches the victim between its elongated and spiny thoracic legs and then chomps happily on its juicy meal.  It is thought that the absence of praying mantises on the Hawaiian Islands allowed the ancestors of the original Eupithecia that colonised the islands to fill their empty niche (Montgomery, 1983; Mironov, 2014).  The caterpillars are not fussy about what they eat, as long as they can grab and keep hold of it and it doesn’t fight back.  They have been recorded as eating flies, braconid wasps, leafhoppers, other Lepidopteran larvae, crickets and even spiders and ants (Montgomery, 1983, Sugiura, 2010).

Eupithecia orichloris attacking and eating an ant (Sugiura 2010)

Last in my list of carnivorous Lepidoptera and perhaps the most surprising are the Vampire Moths.  The phenomenon of “puddling” by butterflies to obtain sodium is well-known (e.g. Boggs & Jackson, 1991) and can be a very attractive sight.

A sight to enjoy – mud puddling https://www.earthtouchnews.com/in-the-field/backyard-wildlife/mud-puddling-the-butterflys-dirty-little-secret/

Somewhat less attractive behaviour is seen in a number of moth species from the Noctuid, Geometrid and Pyralid families which satisfy their desire for Sodium by feeding as adults from the tears and pus of mammals, including humans (Bänziger & Büttiker, 1969).

The Noctuid moth Lobocraspis griseifusa sucking lachrymal fluid (tears) from a human’s eye.  The author, whose eye this is, rather gruesomely asks us to “note the deep penetration of the proboscis between eye and eye lid” Bänziger & Büttiker (1969).

Some Noctuid moths have taken this a step further, perhaps a step too far. Moths of the Genus Calyptra, have very strong proboscises which allow them to feed through the skin of fruit, even oranges, hence their common name, fruit-piecing moths.  A few species however, have adopted a somewhat more interesting diet and have developed a taste for fresh mammalian blood, again, including that of humans, which they suck directly from their victims (Bänziger, 1968).  They are, of course, known as the Vampire Moths!

Calyptra thalictri Vampire Moth in action – note the barbed proboscis

Happy Halloween!

References

Bänziger, H. (1968) Prelimnary observations on a skin-piercing blood-sucking moth (Calyptra eustrigata) (Hmps.) (Lep., Noctuidae)) in Malaya.  Bulletin of Entomological Research, 58, 159-165.

Bänziger, H. & Büttiker, W. (1969) Records of eye-frequenting Lepidoptera from man. Journal of Medical Entomology, 6, 53-58.

Boggs, C.L. & Jackson, L.A. (1991) Mud puddling by butterflies is not a simple matter. Ecological Entomology, 16, 123-127.

Cheema, P.S. (1956) Studies on the Bionomics of the Case-bearing Clothes Moth, Tinea pellionella(L.). Bulletin of Entomological Research, 47, 167-182.

Comstock, J.H. (1879) On a new predaceous Lepidopterous insects.  The North American Entomologist, 1, 25-30.

Cruz-Rodriguez, J.A., Gonzalez-Machoro, E., Gonzales, A.A.V., Ramirez, M.L.R. & Lara, F.M. 92016) Autonomous biological control of Dactylopius opuntia (Hemiptera: Dactlyliiopidae) in a prickly pear plantation with ecological management.  Environmental Entomology, 45, 642-648.

Goeden, R.D., Fleschner, C.A. & Ricker, D.W. (1967) Biological control of prickly pear cacti on Santa Cruz Island, California. Hilgardia, 38, 579-606.

Howard, L.O. (1895) An injurious parasite.  Insect Life, 7, 402-404.

Jeon, J.B., Kim, B.T., Tripotin, P. & Kim, J.I. (2002) Notes on a cicada parasitic moth in Korea (Lepidoptera: Epipyropidae). Korean Journal of Entomology, 32, 239-241.

Liu, Y., Yang, Z., Zhang, G., Yi, Q. & Wei, C. (2018) Cicada parasitic moths from China (Lepidoptera: Epipyropidae): morphology, identity, biology, and biogeography.  Systematics & Biodiversity, 16, 417-427.

Mifsud, D. (1997) Biological control in the Maltese Island – past initaitives and future programmes.  Bulletin OEPP/EPPO Bulletin, 27, 77-84.

Mironov, V.G. (2014) Geometrid moths of the Genus Eupithecia Curtis, 1825 (Lepidoptera, geometridae): prerequisites and characteristic features of high species diversity. Entomological Review, 94, 105-127.

Montgomery, S.L. (1983) Carnivorous caterpillars: the behaviour, biogeography and conservation of Eupithecia (Lepidoptera: Geometridae) in the Hawaiian Islands. GeoJournal, 7, 549-556.

Sugiura, S. (2010) Can Hawaiian carnivorous caterpillars attack invasive ants or vice versa? Nature Precedings

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Entomological Classics – Southwood 1961 – The number of insect species associated with various trees

 

Nineteen-Sixty-One  was a momentous  year for entomology and ecology, although at the time I suspect few realised it.  Skip forward to 2013 when The British Ecological Society published a slim volume celebrating  the 100 most influential papers published in the Society’s journals.  The papers included in the booklet were selected based on the opinions of 113 ecologists from around the world, who were then asked to write a short account of why they thought that paper influential.  I was disappointed not to be asked to write about my nomination but instead asked to write about Maurice Solomon’s 1949 paper in which he formalised the term functional response.

The paper I had wanted to write about was included, but John Lawton had the privilege of extolling its virtues, and given the word limits did a pretty good job.  I do, however, feel that given its importance to ecology and entomology it deserves a bit more exposure, so I am taking the opportunity to write about it here.  I could have included this post in a series I have planned, called Ten Papers that Shook My World, but given the impact that this paper has had on entomologists I felt it deserved an entry in my Entomological Classics series.

For those of you who haven’t come across this paper before, this was an astonishingly influential paper.  Basically, Southwood, who despite his later reputation as one of the ecological greats, was an excellent entomologist, (in fact he was a Hemipterist), wanted to explain why some tree species had more insect species associated with them than others.  He made comparisons between trees in Britain, Russia and Cyprus and demonstrated that those trees that were more common and had a wider range had more insect species associated with them (Figure 1).

Southwood 1961 Fig 1

From Southwood 1961.  I was surprised to see that he had committed the cardinal error in his Figure caption of describing it as Graph and also including the regression equation in the figure pane; two things that I constantly reprimand students about!

Importantly he also showed that introduced trees tended to have fewer insects than native species.  He thus hypothesised that the number of insects associated with a tree species was proportional to its recent history and abundance and was a result of encounter rates and evolutionary adaptation.  He then tested this hypothesis using data on the Quaternary records of plant remains from Godwin (1956) making the assumption that these were a proxy for range as well as evolutionary age.

He commented on the outliers above and below the line suggesting that those above the line were a result of having a large number of congeners and those below the line either as being taxonomically isolated and/or very well defended.

He then went on to test his ideas about the evolutionary nature of the relationship by looking at trees and insects in Hawaii, (ironically this appeared in print (Southwood, 1960), before the earlier piece of work (Journal of Animal Ecology obviously had a slower turnaround time in those days than they do now).

Hawaiin figure

Figure 2.  Relationship between tree abundance and number of insect species associated with them (drawn using data from Southwood 1960).

Considering the research that these two papers stimulated over the next couple of decades, what I find really odd, is that Southwood, despite the fact that he was dealing with data from islands and that Darlington (1943) had published a paper on carabids on islands and mountains in which he discussed species-area relationships and further elaborated on in his fantastic book (Darlington, 1957), did not seem to see the possibility of using the species-area concept to explain his results.  It was left to Dan Janzen who in 1968 wrote

It is unfortunate that the data on insect-host plant relationships have not in general been collected in a manner facilitating analysis by MacArthur and Wilson’s methods (as is the case as well with most island biogeographical data). What we seem to need are lists of the insect species on various related and unrelated host plants, similarity measures between these lists (just as in Holloway and Jardine’s 1968 numerical taxonomic study of Indo- Australian islands), knowledge of the rates of buildup of all phytophagous insect species on a host plant new to a region, where these species come from, etc. Obviously, the insect fauna must be well known for such an activity. The English countryside might be such a place; it has few “islands” (making replication difficult) but a very interesting “island” diversity, with such plants as oaks being like very large islands and beeches being like very small ones, if the equilibrium number of species on a host plant (Elton, 1966; Southwood, 1960) is any measure of island size.”

 

In 1973 Dan Janzen  returned to the subject of trees as islands and cited Paul Opler’s 1974 paper in relation to the fact that the number of  herbivorous insects associated with a plant increases with the size of the host plant population (Figure 3), and further reiterated

Opler Figure

Figure 3.  Opler’s 1974 graph showing relationship between range of oak trees in the USA and the number of herbivorous insect species associated with them.

 his point about being able to consider trees as ecological islands.  Opler’s 1974 paper is also interesting in that he suggested that this approach could be used for predicting pest problems in agricultural systems, something that Don Strong and colleagues did indeed do (Strong et al., 1977; Rey et al., 1981), and that the concept of habitat islands and the species-area relationship could be used when designing and evaluating nature reserves, something which indeed has come to pass.

Again in 1974 but I think that Strong has precedence because Opler cites him in his 1974 paper, Don Strong reanalysed Southwood’s 1961 data using tree range (based on the Atlas of the British Flora)  as the explanatory variable  (figure 4) to explain the patterns seen.

Strong Figure

Figure 4Strong’s reworking of Southwood’s 1961 insect data using the distribution of British trees as shown in Perring & Walters1 (1962).

The publication of this paper opened the floodgates, and papers examining the species-area relationships of different insect groups and plant communities proliferated (e.g  leafhoppers (Claridge & Wilson, 1976); bracken (Rigby & Lawton, 1981); leaf miners (Claridge & Wilson, 1982); rosebay willow herb (McGarvin, 1982), with even me making my own modest contribution in relation to Rosaceous plants   (Leather, 1985, 1986).

Although not nearly as popular a subject as it was in the 1980s, people are still extending and refining the concept  (e.g. Brändle & Brandl, 2001; Sugiura, 2010; Baje et al., 2014).

Southwood (1961) inspired at least two generations of entomologists and ecologists, including me, and is still relevant today.  It is truly an entomological (and ecological) classic.

References

Baje, L., Stewart, A.J.A. & Novotny, V. (2014)  Mesophyll cell-sucking herbivores (Cicadellidae: Typhlocybinae) on rainforest trees in Papua New Guinea: local and regional diversity of a taxonomically unexplored guild.  Ecological Entomology 39: 325-333

Brändle, M. &Brandl, R. (2001). Species richness of insects and mites on trees: expanding Southwood. Journal of Animal Ecology 70: 491-504.

Claridge, M. F. &Wilson, M. R. (1976). Diversity and distribution patterns of some mesophyll-feeding leafhoppers of temperate trees. Ecological Entomology 1: 231-250.

Claridge, M. F. &Wilson, M. R. (1982). Insect herbivore guilds and species-area relationships: leafminers on British trees. Ecological Entomology 7: 19-30.

Darlington, P. J. (1943). Carabidae of mountains and islands: data on the evolution of isolated faunas and on atrophy of wings. Ecological Monographs 13: 37-61.

Darlington, P. J. (1957). Zoogeography: The Geographical Distribution of Animals. New York: John Wiley & Sons Inc.

Elton, C. S. (1966). The Pattern of Animal Communities. Wiley, New York.

Holloway, J. D., & Jardine, N. (1968). Two approaches to zoogeography: a study based on the distributions of butterflies, birds and bats in the Indo-Australian area. Proceedings of the Linnaean Society. (London) 179:153-188.

MacArthur, R. H. & Wilson, E.O. (1967). The Theory of Island Biogeography. Princeton University Press, Princeton, N. J

Janzen, D. H. (1968). Host plants as islands in evolutionary and contemporary time. American Naturalist 102: 592-595.

Janzen, D. H. (1973). Host plants as islands II.  Competitive in evolutionary and contemporary time. American Naturalist 107: 786-790.

Kennedy, C.E.J. & Southwood, T.R.E. (1984) The number of species of insects associated with British trees: a re-analysis. Journal of Animal Ecology 53: 455-478.

Leather, S. R. (1985). Does the bird cherry have its ‘fair share’ of insect pests ? An appraisal of the species-area relationships of the phytophagous insects associated with British Prunus species. Ecological Entomology 10: 43-56.

Leather, S. R. (1986). Insect species richness of the British Rosaceae: the importance of hostrange, plant architecture, age of establishment, taxonomic isolation and species-area relationships. Journal of Animal Ecology 55: 841-860.

Macgarvin, M. (1982). Species-area relationships of insects on host plants: herbivores on rosebay willowherbs. Journal of Animal Ecology 51: 207-223.

Opler, P. A. (1974). Oaks as evolutionary islands for leaf-mining insects. American Scientist 62: 67-73.

Perring, F.J. & Walters, S.M. (1962) Atlas of the British Flora BSBI Nelson, London & Edinburgh.

Preston,  C.D., Pearman, D.A. & Tines, T.D. (2002) New Atlas of the British and Irish Flora: An Atlas of the Vascular Plants of Britain, Ireland, The Isle of Man and the Channel Islands. BSBI, Oxford University Press

Rigby, C. & Lawton, J. H. (1981). Species-area relationships of arthropods on host plants: herbivores on bracken. Journal of Biogeography 8: 125-133.

Solomon, M. E. (1949). The natural control of animal populations. Journal of Animal Ecology 18: 1-35

Southwood, T. R. E. (1960). The abundance of the Hawaiian trees and the number of their associated insect species. Proceedings of the Hawaiian Entomological Society 17: 299-303.

Southwood, T. R. E. (1961). The number of species of insect associated with various trees. Journal of Animal Ecology 30: 1-8.

Sugiura, S. (2010). Associations of leaf miners and leaf gallers with island plants of different residency histories.  Journal of Biogeograpgy 37: 237-244

Rey, J.R.M.E.D. & Strong, D.R. (1981) Herbivore pests, habitat islands, and the species area relation. American Naturalist 117: 611-622.

Strong, D. R. (1974). The insects of British trees: community equilibrium in ecological time. Annals of the Missouri Botanical Gardens 61: 692-701.

Strong, D.R., D., M.E., & Rey, J.R. (1977) Time and the number of herbivore species: the pests of sugarcane. Ecology 58: 167-175

 

1Postscript

The Atlas of the British Flora by Perring and Walters (1962) was an iconic piece of work, although not without its flaws.  As with many distribution atlases it is based on a pence or absence score of plant species within one kilometre squares.  So although it is a good proxy or range it does not necessarily give you an entirely reliable figure for abundance.  A dot could represent a single specimen or several thousand specimens.   Later authors attempted to correct for this by using more detailed local surveys e.g. tetrads.  It must have been particularly galling for  Southwood that the Atlas didn’t appear until after he had published his seminal papers, but he later made up for it by reanalysing and extending his data from that original 1961 paper (Kennedy et al., 1984).

Those of us working in this area using the original Atlas had to count the dots by hand, a real labour of love especially for those widely distributed species; the new edition (Preston et al., 2002) actually tells you how many dots there are so the task for the modern-day insect-plant species-area relationship worker is much easier 😉

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