YouTube VideoBanana-Eating Moth Evolved in Less Than 1000 Years?
by Rich Deem

Introduction

Probably most of you have heard of the banana moth—what Kenneth Miller, Professor of Biology at Brown University, has called the "best example of evolution" in action. Miller made the assertion in a televised debate in 1997. Here is the quote:

"And I can give you several examples of new species that have emerged within human observation. The best example that I can give you is the butterfly, the genus of butterfly known as Hedylepta. Hedylepta is a genus of butterfly that feeds on various plants, it’s endemic to the Hawaiian Islands, which means it’s only found there. And there turn out to be two species of Hedylepta with mouthparts that only allow them—only allow them to feed on bananas. Now why is that significant? It is significant because bananas are not native to the Hawaiian Islands. They were introduced about 1000 years ago by the Polynesians; we know this from the written records of the Hawaiian kingdom. And what that means is, that by mutation and natural selection, these two species have emerged on the Hawaiian Islands within the last 1000 years. And I think that’s a very good case in point."1

The story sounded a little too good to be true, so I did some investigation. Does this example really show that a species can evolve in less than 1000 years?

What Miller got wrong

First off, Hedylepta is a moth—not a butterfly. The fact that Miller didn’t even get the right kind of Lepidoptera correct makes the story immediately suspect. In addition, in written responses, Miller got the spelling of the genus wrong also, listing it as “Hedylypta” instead of Hedylepta (if you search for the term “Hedylypta,” you will find the error repeated on many atheistic websites). Miller’s information comes from a short article entitled, "Possible evidence of rapid evolution in Hawaiian moths," published in the journal Evolution in 19602 (although I doubt he actually read the article, because of the mistakes). This article is only two pages long and indicates that five species (not two, as claimed by Miller) feed exclusively on banana leaves. In the article, there is no discussion of the evolution of "mouthparts that only allow them to feed on bananas."

Most of the information in Zimmerman's article comes from his volume Insects of Hawaii volume 8,3 which documents the Lepidoptera of the Hawaiian Islands. Nearly all the species were originally classified in the genus Omiodes, which were renamed to Hedylepta by Zimmerman in his 1958 volume. However, all the species of Hedylepta were renamed back to Omiodes in 1989.4 So, Miller also got the name of the genus wrong.

Omiodes characteristics

There were 23 species of Omiodes, most of which were discovered around the turn of the 20th century. The details are included in the table below:

23 Endemic Species of Omiodes in the Hawaiian Islands3
Species Discovery Island(s) Food source
accepta Butler, 1877 Kauai, Oahu, Molokai, Maui, Hawaii grasses, sedges, sugar cane
anastrepta Meyrick, 1899 Oahu, Molokai, Hawaii sedges
anastreptoides Swezey, 1913 Hawaii sedges
antidoxa Meyrick, 1904 Kauai, Oahu sedges
asaphombra Meyrick, 1899 Kauai, Oahu, Molokai, Hawaii Joinvillea, Flagelleraceae
blackburni Butler, 1877 Kauai, Oahu, Molokai, Maui, Lanai, Hawaii palms, bananas
continuatalis Wallengren, 1860 Kauai, Oahu, Molokai, Maui, Lanai, Hawaii grasses
demaratalis Walker, 1859 Niihau, Kauai, Oahu, Molokai, Maui, Hawaii grasses
epicentra Meyrick, 1899 Oahu sedges
euryprora Meyrick, 1899 Hawaii bananas
fullawayi Swezey, 1913 Hawaii bananas
giffardi Swezey, 1921 Hawaii grasses
iridias Meyrick, 1899 Hawaii lilies
laysanensis Swezey, 1914 Laysan grasses
localis Butler, 1879 Kauai, Oahu, Molokai, Maui, Lanai, Hawaii grasses
maia Swezey, 1909 Kauai, Oahu bananas
meyricki Swezey, 1907 Hawaii bananas
monogona Meyrick, 1888 Kauai, Oahu, Molokai, Maui, Lanai, Hawaii legume Erythrina
monogramma Meyrick, 1899 Kauai, Oahu, Molokai, Hawaii lilies
musicola Swezey, 1909 Molokai, Maui bananas
pritchardii Swezey, 1948 Hawaii palms
scotaea Hampson, 1912 Oahu, Molokai, Hawaii lilies
telegrapha Meyrick, 1899 Hawaii Unknown

All the caterpillars of Hawaiian Omiodes species are leaf rollers. The caterpillars use silk to form a secluded retreat from which they can eat leaves undisturbed. So, all the Hawaiian Omiodes species eat leaves. None eat fruit.5 So, no specialized mouth parts are necessary to eat one kind of leaf versus another.

Demise of banana-feeding Omiodes

Near the turn of the 20th century parasitic wasps were introduced into Hawaii to control some of the agricultural Lepidoptera pests. Unfortunately, these wasps parasitized not only non-native Lepidoptera pests, but also a number of Omiodes species, including all the banana-eating species. In fact, original descriptions of the discovery of Omiodes meyricki indicate that it was under heavy predation even when first discovered, over a century ago.6 Zimmerman's volume does not even include taxonomic keys to 8 Omiodes caterpillars, including two banana-eating species, because they were so rare.7 As of now, 14 species of Hawaiian Omiodes are now on the endangered list, including all the species that feed exclusively on banana.8

Molecular phylogeny of Omiodes

The claim that the banana-eating moths evolved in the last 1,000 years implies that those species arose from some other related species. Zimmerman suggested that they all evolved from Omiodes blackburni, since it also eats bananas (although it eats coconut palms and native palms, as well). The question of whether or not phylogeny is related to food source is best answered through studies of molecular phylogeny. The only such study on Omiodes and related genera was published in 2012.9 Scientists sequenced 5 genes from 81 taxa, including 10 Hawaiian Omiodes. None of the five banana-eating species were sequenced, because they are probably extinct and no specimens could be found. However, the phylogenetic tree of the Hawaiian taxa are reproduced right, with food source added next to each species. The Hawaiian Omiodes cluster into two main groups. Both clusters includes species that eat grasses and both include a species that eats lilies. Surprisingly, Omiodes blackburni, which eats palms and bananas clusters directly with Omiodes scotaea, which eats lilies. So, it is pretty clear that food source has nothing to do with phylogeny.

Indiscriminate eating

Does it really require evolution for a moth species to jump from one food source to another? Some species of Omiodes are rather indiscriminate eaters. For example, Omiodes blackburni eats not only native Pritchardia palms, but also coconut palms and bananas.3 Omiodes accepta feeds on a number of grasses, including Digitaria prurient, Oplismenus compositus, Pampas grass, Panicum nephehphilum, Paspalum conjugatum, Paspalum orbiculare, and the sedge Baumea meyenii.10 It was originally described as feeding only on grasses.11 Later, it was also described as feeding on sugar cane.12 Sugar cane was not introduced into Hawaii until 150 years ago, so Omiodes accepta must have evolved really quickly! In fact, there might have been even more species that fed on banana, since a 1924 publication indicated that there were at least two "undescribed species of Omiodes has been reared from banana on each of the Islands" of Maui and Kauai,13 in addition to the other five. The fact that many of these species can use multiple food sources argues against the idea that evolution is required for a species to change its food source.

Conclusion Top of page

So, what did Kenneth Miller get right about the banana-eating "Hedylepta." It turns out, very little:

Fact Ken Miller Actual
Kind of Lepidoptera Butterfly Moth
Genus Hedylepta Omiodes
# species 2 5
Specialized mouth parts Yes No
Changing food source requires evolution Yes No
Food source Only banana Banana & ?

In fact, Miller got the genus wrong, the number of species wrong and outright lied about the evolution of "specialized mouth parts." The idea that food source is somehow related to phylogeny has also been proven false. So, the only part of the story that might be correct is that these species feed exclusively on banana. However, since all the banana-feeding species haven't been seen in years and are probably extinct, even that claim is no longer testable. And, many species of Omiodes feed on multiple food sources, some of which have been introduced into the Islands only in the last 150 years. So, it turns out that rather than being the "best example of evolution," the banana eating moth is one of the poorest examples of evolution.

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References Top of page

  1. PBS Firing Line Debate on Creation/Evolution. "Resolved: Evolution Should Acknowledge Creation." December 19, 1997.
  2. Zimmerman, E. 1960. Possible evidence of rapid evolution in Hawaiian moths. Evolution 14: 137-138.
  3. Zimmerman, E. 1958. Insects of Hawaii, Volume 8.
  4. Munroe, E., 1989. Changes in Classification and Names of Hawaiian Pyraloidea since the Publication of Insects of Hawaii USA Volume 8 by E.C. Zimmerman 1958 Lepidoptera. Bishop Museum Occasional Papers 29:199-212.
  5. There is one Hawaiian banana moth that has special fruit-piercing mouth parts. It is Eudocima fullonia (aka, Banana Fruit Piercing Moth). However, it is native to the the Indo-Malaysian region and was imported into Hawaii. In addition, it eats not only bananas, but also native wild trees, shrubs and vines. Here is an excerpt from on article on Eudocima fullonia from the USDA website:

    Eudocima fullonia, also known as the fruit-piercing moth is a significant pest of citrus and several commercial fruit crops (Baptist 1944, CAB 2004). This insect occurs in Africa, Asia, Oceania, but is native to the Indo-Malaysian region (Baptist 1944, APPC 1987, CABI/EPPO 2001). Unlike most other moths, E. fullonia uses its proboscis to puncture fleshy plant parts, typically fruit, to feed (Bänziger 1982). Larvae have no such requirement, so host plants typically differ between larval and adult stages. Larvae are primarily foliage feeders of several wild trees, shrubs and vines within the families Menispermaceae and Fabaceae. (from http://www.aphis.usda.gov/plant_health/plant_pest_info/pest_detection/downloads/pra/efulloniapra.pdf)

  6. "On the leaves of wild bananas growing in a gulch near the upper part of the sugar plantation, at Honomu, Hawaii, I observed some caterpillars of a species of Omiodes not as yet to be determined till the caterpillars have matured.* I also found several batches of eggs which proved to be the same species. Very few caterpillars hatched from these eggs, however, as they were nearly all parasitized, the parasites emerging March 25-30. There were 1 to 3 per egg. They gnawed out before their wings had expanded.
    I referred specimens to Dr. Perkins, who, on comparing them with the original description of Triciwgrwrnma pretiosa finds it is apparently this species. I have since observed them at the Capitol grounds, Honolulu, in the act of ovipositing in eggs of the palm leaf-roller (Omiodes blackburni). I take it to be the first record of their presence here.
    *On maturity, these proved to be a new species, which has been described by Mr. Swezey under the name Omiodes meyricki. Bull. V, Exp. Sta. H. S. P. A. Div. Ent. p. 24, 1907.—[Eds]." Proc Hawaiian Entomol Soc 2(02): 035-087 August, 1908 – June 1909.
  7. "Unfortunately caterpillars of some of the species, although they have been found, have not been described or preserved, and it is impossible to give a key to the caterpillars of all of the species at this time. Thus, the key omits the following species: asaphombra, epicentra, euryprora, fullawayi, giffardi, laysanensis, pritchardii, telegrapha." (Zimmerman, E. 1958. Insects of Hawaii, Volume 8, pp. 71-72).
  8. Hawaii's Extinct species -- Insects, Hawaii Biological Survey, revised 21 March 2002.
  9. William P. Haines, Daniel Rubinoff. 2012. Molecular phylogenetics of the moth genus Omiodes Guenée (Crambidae: Spilomelinae), and the origins of the Hawaiian lineage. Molecular Phylogenetics and Evolution 65: 305–316.
  10. Omiodes accepta From Wikipedia, April 30, 2014.
  11. Swezey, O.H. 1907. Proceedings of the Hawaiian Entomological Society I, Part 4. Proc Hawaiian Entomol Soc 01(4):111-161.
  12. "We have a parallel case in five other species of leafrollers of the same genus of moths, which are naturally grassfeeders, but one species [Omiodes accepta] of the five has taken to feeding on sugar-cane, and sometimes has been a very injurious pest where the canefields adjoin grassy regions. The other four species, however, of this group continue feeding only on grasses." Swezey, O.H. 1924. The Insect Fauna of Trees and Plants as an Index of Their Endemicity and Relative Antiquity in the Hawaiian Islands. Proc Hawaiian Entomol Soc 06(01):195-210. (p. 207)
  13. "INSECT FAUNA OF NATIVE BANANAS. A weevil, Polytus mellerborgi (Boh.), whose larvae feed in the base of the stem and corm; six or more leaf-rollers, Omiodes blackburni (Butl.) on all the Islands, O. euryprora Meyr., O. meyricki Sw. and O. fullawayi Sw. on Hawaii, O. musicola Sw. on Maui, O. maia Sw. on Oahu and Kauai; an undescribed species of Omiodes has been reared from banana on each of the Islands. Maui and Kauai."
    Swezey, O.H. 1924. The Insect Fauna of Trees and Plants as an Index of Their Endemicity and Relative Antiquity in the Hawaiian Islands. Proc Hawaiian Entomol Soc 06(01):195-210.

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Last Modified May 4, 2014

 

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