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The LEPIDOPTERIST5, News
Volume 11 1957 Number 6
THE BREEDING IN CAPTIVITY OF THE HYBRID PAPILIO GLAUCUS $ X PAPILIO EURYMEDON d
by C. A. Clarke and P. M. Sheppard
In a previous paper (Clarke & Sheppard, 1955) we described the breeding in captivity of the hybrid swallowtail Papilio rutulus Lucas $ X Papilio glaucus Linne d- Since an understanding of the relationship between P. glaucus and its near relatives must be based in part on genetic information it seemed worth while investigating the closely related P. eurymedon Lucas. The account that follows gives details of the hybrid between P. glaucus $ and P. eurymedon d which we obtained in 1956 on three occasions.
The P. eurymedon pupae were kindly supplied by Mr. Noel McFar-land in 1955, from Beverly Hills, California. They were the offspring of butterflies which had emerged in the early spring. The pupae overwintered; the three d d used for crossing emerged in May 1956.
The P. glaucus pupae were descendants of those originally sent us by Mr. Eugene Dluhy, from Chicago, Illinois. They had been principally used for work on the genetics of the two forms of glaucus female, the results of which are published elsewhere (Clarke & Sheppard, in press). The table gives the matings which we made, some details of their fertility, the dates of the emergences of the hybrid butterflies, and the number of pupae that remain. From the brood numbers, the pedigree of the glaucus females can be found by reference to the other paper (Clarke & Sheppard, in press). BREEDING METHODS AND LIFE HISTORY
The butterflies were mated by the hand-pairing technique, (Clarke, 1952; Clarke & Sheppard, 1955). Breeding was carried out at room temperature or a little above, throughout the summer months. The caterpillars were fed on Liriodendron which they ate readily. This was in striking contrast to all the eurymedon larvae, also received from Mr. McFarland, which invariably refused to eat this food plant. Brower (1957) also states that he has never known eurymedon larvae to feed on Liriodendron.
DESCRIPTION OF HYBRID LARVAE
The full grown hybrid larva resembled that of glaucus except in the eye-spot on the thorax which is pear-shaped with the narrow portion towards the middle line, whereas in glaucus it is approximately circular in outline. A second yellow area, medial to the main eye-spot, was also present in most of the hybrid caterpillars. This varied in appearance between merely a black line and a yellow triangular area bordered by black. The photograph illustrates the two degrees of expression in the same hybrid larva. The element seems to represent a reduced version of the large black-bordered yellow patch present in this position in eurymedon larvae. Figure 1 shows the form of the eye-spot in P. glaucus, the hybrid, and P. eurymedon.
201
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Clarke & Sheppard: Hybrid Papilio
Vol.11: no.6
MATINGS OF PAPILIO GLAVCUS 9 X PAPILIO EURYMEDON #
Mating no. Brood no. and date and form of Father's of mating mother symbol*
Remarks Emergences Remaining
pupae
954 31/5/56 640 (black) a
957
31/5/56
960
1/6/56
968
3/6/56
974
6/6/56
975 6/6/56
640 (black) J3
639 (yellow) 7
640 (black) 7
669 (yellow) 7
669 (yellow) £
978 6/6/56 669 (yellow) a
|
999 10/6/56 |
650 (yellow) |
|
1002 11/6/56 |
650 (yellow) |
|
1009 13/6/56 |
670 (black) |
No. of eggs laid not known. "At one time about 15 larvae."
19 eggs laid. Began to darken but collapsed.
No eggs laid.
Laid 18 eggs, 12 fertile, 6 infertile (4 green, 2 collapsed)
Laid several infertile eggs.
Laid fertile eggs. Last two males dead ; taken from pupal cases.
Laid about 50 eggs, all fertile, all hatched. Brood virused ; 2 reached pupal stage but both died.
No eggs laid.
Laid 17 infertile eggs.
No eggs laid.
#28/8/56 3 31/8/56
# 1/9/56
#13/1/57 #30/3/57
1 (9?)
(19/9/57)
#13/8/56 $ 18/8/56 #23/8/56 #28/8/56 #16/9/56
4(all9 $ ?) 19/9/57
#25/8/56 #27/8/56 #27/8/56 #27/8/56 # 1/9/56 #30/9/56 #16/11/56
* The Greek letters in the third column indicate the multiple matings of the # # and the order of mating can be seen from the date in the first column.
1957 The Lepidopterbts' News 203
Fig. 1. Thoracic eye-spots of full-grown larvae: left, Papilio glaucus; center, F1 hybrid P. glaucus $ X P. eurymedon $ ; right, P. eurymedon. (Photo of P. eurymedon by L. P. Brower.)
DESCRIPTION OF HYBRID PUP^
The male pupae resembled those of glaucus and there were no individuals of the partially green form as is sometimes found in P. eurymedon (Brower, 1957). The presumed female pupse, none of which has yet emerged (September 1957), are very large and though looking healthy appear to be going through a second winter. This phenomenon did not occur in any of the glaucus X rutulus hybrids (Clarke & Sheppard, 1955), nor among several hundred glaucus pupae kept under similar conditions over the past few years. If the female butterflies do eventually emerge it seems more than probable that they will be black, since we have shown that in glaucus almost invariably the colour of the female offspring is the same as that of the mother. This shows that black is not controlled by an autosomal gene (Clarke & Sheppard, in press).
Fig. 2. Papilio males, upperside left, underside right of each specimen- left, P. glaucus; center, Ft hybrid P. glaucus 9 X P. eurymedon $ ; right, P. eurymedon.
DESCRIPTION OF MALE HYBRID BUTTERFLIES
In general the hybrids resemble glaucus much more than eurymedon. Thus, the yellow ground colour on the wings is no paler than the palest glaucus we have observed, and the amount of black on both the forewings and the hindwings also resembles that in glaucus, although in general there
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Clarke & Sheppard: Hybrid Papilio
Vol.11: no.6
is slightly more black than in typical glaucus specimens. On the underside the black markings in the hybrid are wider and darker than those of the darkest glaucus we have seen. The orange in the outer spots of the underside of the hindwing tends to be intermediate between glaucus and eurymedon and more orange than in rutulus X glaucus hybrids (Clarke & Sheppard, 1955). The only feature in which the hybrids resemble eurymedon rather than glaucus is in the nature of the yellow submarginal lunules, which form a continuous band (as in the rutulus X glaucus hybrids) and not a series of discrete spots as in all the glaucus we have bred.
Figure 2 shows a cf glaucus, 2l <$ hybrid, and a S eurymedon for comparison.
DISCUSSION
1. Larval food plant. The ability of the larva to feed on Liriodendron seems to be dominant as was the case with the rutulus X glaucus hybrid. Appropriate backcrosses (or F2) of the hybrid to eurymedon would show whether this character is controlled unifactorially or multifactorially.
2. Wing-pattern of butterflies. The pattern in glaucus seems generally to be dominant to that of eurymedon, but again further generations must be obtained before the number of genes controlling this character can be estimated.
3. Larval spot markings. These were intermediate between the parent forms and again no further information is available as to the mode of their inheritance.
4. Fertility.
a) The backcrosses to P. glaucus. Fertile eggs, as judged by change in colour, were obtained on eight occasions when hybrid males were backcrossed to glaucus females. In five of these broods no caterpillars hatched, while in the remaining three, although larvae were produced, all eventually died of disease. It is of note that in two of these families many of the eggs, although they blackened, did not hatch. The findings generally are in contrast with the single fertile backcross mating made with the rutulus X glaucus hybrid in which the fertile eggs all hatched.
b) Sex ratio. It has already been stated that in the eurymedon X glaucus hybrids no female butterflies have yet emerged, and this agrees with Haldane's rule (Haldane, 1922) that when there is any abnormality in one of the sexes or when one is deficient, it is always the heterogametic sex. Our result with these hybrids is in contrast with those of the rutulus X glaucus hybrids, where the sex ratio was normal, as was the time of the emergences of the butterflies.
CONCLUSION
The evidence on the difference between the two hybrids, with respect to (1) the development in eggs of the back crosses, (2) the sex ratio, and (3) the time of development of the female pupae, suggests that there is a greater
1957
The Lepidopterists' News
205
genetic difference between eurymedon and glaucus than there is between rutulus and glaucus. This is in agreement with morphological considerations including an examination of the male genitalia (Brower, 1957). Further evidence on the inter-relationships of the butterflies should be obtainable by investigating the hybrid between P. rutulus and P. eurymedon.
ACKNOWLEDGMENTS
We are very grateful to Mr. Noel McFarland for sending us pupae of P. eurymedon, and Dr. L. P. Brower for reading the manuscript, for his helpful suggestions, and for sending us the photograph of the P. eurymedon larva. One of us (P. M. Sheppard) is grateful for the continued support of the Nuffield Foundation.
Literature Cited Brower, Lincoln Pierson, unpubl. Speciation in the Papilio glaucus group. Ph.D.
thesis, Yale University. June 1957. Clarke, C. A., 1952. Hand-pairing of Papilio machaon in February. Ent. Rec. Journ.
Far. 64: 98. Clarke, C. A., & P. M. Sheppard, 1955. The breeding in captivity of the hybrid
Papilio rutulus 2 X Papilio glaucus $. Lepid. News 9: 46-48.
................, 1956. Hand-pairing of butterflies. Lepid. News 10: 47-53.
.--.........--., in press. The genetics of some mimetic forms of Papilio dardanus, Brown
and Papilio glaucus, Linn. Journ. Genet. Haldane, J. B. S., 1922. Sex ratio and unisexual sterility in hybrid animals. Journ.
Genet. 12: 101-109.
(CAC) Dept. of Medicine, University of Liverpool, Liverpool, ENGLAND
and (PMS) Dept. of Zoology, University of Liverpool, Liverpool, ENGLAND
A RECORD OF THE BLACK WITCH, EREBUS ODORA (NOCTUIDv^),
IN ALASKA
On October 4, 1957, a female of Erebus odora Linne was found by Nedria Mielke at Auke Bay, 12 miles north of Juneau, Alaska. The specimen was in excellent condition when found but the margins of the wings became slightly tattered from confinement in a box before its demise. The specimen was given to E. L. Keithahn, curator of the Territorial Museum in Juneau, Alaska. It has been photographed and is now deposited in the museum where I had the opportunity to examine and identify it.
It has been known for a long time that isolated specimens of this moth flew or were carried by wind currents far to the north of their normal habitat in the West Indies and Mexico.
Specimens have been reported from as far north as Canada and west to California. However, as far as I can ascertain, this form has not been previously reported from Alaska.
Paul J. Spangler, U. S. Fish & Wildlife Service, Juneau, Alaska, U. S. A.