THE POPULATION BIOLOGY OF THE BUTTERFLY, EUPHYDRYAS EDITHA. VIII. OVIPOSITION AND ITS RELATION TO PATTERNS OF OVIPOSITION IN OTHER BUTTERFLIESl PATRICIA A. LABINE Biomedical Data Processing Training Program, School of Public Health, The University of Michigan, Ann Arbor, Michigan Received December 15, 1967 This paper is one of a continuing series Similar data obtained from the literature investigating the population biology of and from personal communications for three Euphydryas editha (Nymphalidae: Nym­ other butterflies, Cercyonis oetus, Colias phalinae). The life history and general eurytheme, and Heliconius erato, are pre­ biology of this butterfly have been de­ sented in Figures 1b, Ic, and Id, The size scribed in preceding papers that have dealt of each butterfly and the size of its egg are with aspects of its ecology, phenetics, and illustrated in the figures. reproductive biology (Labine, 1964; Ehr­ An estimate of the total number of eggs lich, 1965; Ehrlich and Mason, 1966; expected per female under laboratory con­ Labine, 1966a; Mason, Ehrlich, and Em­ ditions was calculated as the sum of the mel, 1967, 1968; Johnson, Keith, and Ehr­ average number of eggs produced by fe­ lich, 1968). males of age x, weighted by the proportion The present paper is concerned with ovi­ of adult females surviving to age x. This position and its ecological consequences. measure is somewhat analogous to the net "Oviposition" is used here in a broad sense reproductive rate, R o, usually calculated and is meant to include oviposition behav­ from life table data, however, in our case ior, egg number, egg size, rate of oviposi­ only adult mortality is considered, and we tion, etc. Attempts to interpret the ovi­ are concerned with the total number of position pattern of Euphydryas editha led eggs, not just female eggs. These estimates to comparisons with what is known of ovi­ are also noted in the figures. The value for position patterns in other butterflies. Heliconius was not calculated, but taken directly from Crane (1955). OVIPOSITION IN THE LABORATORY Methods used in maintaining oviposit­ OVIPOSITION IN NATURAL POPULATIONS ing Euphydryas editha females in the lab­ Eleven complete oviposition sequences of oratory have been described elsewhere wild Euphydryas editha females were ob­ (Labine, 1966a). The butterflies used in served in the Woodside population. One this study were collected as late instar lar­ behavior pattern was consistently seen. vae from the population in Woodside, Cali­ The female would land in the ground cover, fornia. Survival and fecundity values com­ which in most parts of the colony was less piled from 53 females are presented in than 6 inches high and consisted predomi­ Table 1. nantly of the larval foodplant Plantago erecta. She would then "search" for a 1 This work was supported in part by USPHS variable period of time, crawling through Training Grants No. 5T1 GM 892-06, and 5T01 the ground cover, her wings slowly clapping GM 00365-05, and Grants GM-1430 and GB-5645 together. Oviposition would begin once the from the National Science Foundation. Present address: Dept. Biology, Williams College, Wil­ female settled quietly and folded her wings. liamstown, Mass. The sequence was always terminated by EVOLUTION 22: 799-805. December, 1968 799 800 PATRICIA A. LABINE the female flying off abruptly. Mean dura­ a. Euphydryas editha (No53") tion (±S.E.) of oviposition, starting from III the time the female initially landed on the 8-(98 .. ...... LL . Il g ground, was 29.7 ± 2.8 min. o " ... Eggs were laid in clusters. In five in­ ~ \. ca stances the eggs were not placed on the L: \ .. foodplant, but on unidentified seedlings ~:iS . o Ig w \ near Plantago plants. The mean size of ~ eight clusters that were counted was 45.2 a:: \... ~ ± 6.1 eggs (range: 75 to 21 eggs). This . value is likely to be an underestimation of °0 10 20 30 DAYS the true mean cluster size of Euphydryas editha. Females in the laboratory laid the b. Cercyonis oetus (N::40U') 9 largest clusters on the first few days of ~ S I~ 8 oviposition. The above field observations, with one exception, occurred late in the ~ . adult flight season which lasts approxi­ ~ <, mately one month, and probably did not g include the first large clutches of females. Oviposition sequences were observed on the 111 \-\2~ EGGS following days, counting as day 1 the date i PER FEMALE of the first appearance of adults in the ..... colony for that year: day 3, 20, 21, 21, 20 DAYS 24, 28, 28, 28. c. Colias eurytheme DISCUSSION (N=34rj~) (98III ........ The data presented above suggest that 8 - , .. there are at least five components of varia­ lL. •••.. \ o ... tion in oviposition patterns of butterflies. (fl wcr.f1 ....... c 1) Number of eggs laid} ~ II . ~ - Reproductive ~:iS h~ 1')$ \ z Gl 2) Egg size effort ~ 704 \ Distribution cr EGGS ". ~ • PER FEMALE . 3) Onset of oviposition of reproduc- 4) Rate of oviposition - tive effort 5) Cluster size ) over space DAYS and time .d. Heliconius erato ~ (Curves approximate) ~S I~ 8 FIG. 1. Survivorship and fecundity curves for laboratory populations. Dotted line = survivor­ b "ifl ship; solid line = fecundity. The scale of the drawings is indicated, and is the same for all fig­ ures. (a) Butterfly figure from Wright (1905); egg size, personal observation. (b) Data and egg ,~~ O',~'-"-". size from Thomas Emmel (pers. comm.); butter­ !. "i fly figure from Seitz (1924). (c) Data from Stern ~ PER FEMALE and Smith (1960) and Ray F. Smith (pers. comm.); butterfly figure from Wright (1905); egg size from Edwards (1884) and Comstock (1927). (d) Data from Crane (1955); egg size from Beebe et aI. (1960); butterfly figure is an approxima­ tion. OVIPOSITION PATTERNS OF EUPHYDRYAS EDITHA 801 TABLE 1. Survival and fecundity data compiled Callas philodice, making the taxonomic from 53 adult Euphydyras editha under laboratory status of some individuals uncertain. In conditions. Survival value at day x is the propor- tion of adult females surviving to age x. Fecundity the cooler areas of California, the source of value at day x is the average number of eggs pro- the butterflies used for the oviposition duced by a female of age x. data, the winter is passed by a dormant larval phase. In warmer areas Colias Day Survival Fecundity Day Survival Fecundity eurytheme has continuous generations. 1 1.00 71.8 17 0.55 13.4 Cercyonis oetus (Nymphalidae: Satyr­ 2 1.00 108.6 18 0.55 7.2 inae) is part of a large, highly variable 3 0.96 73.6 19 0.51 4.4 group of butterflies with uncertain taxo­ 4 0.96 101.4 20 0.45 3.8 5 0.94 62.0 21 0.30 6.9 nomic delineations. Cercyonis oetus ranges 6 0.94 63.3 22 0.25 2.2 from the Pacific coast to the eastern edge 7 0.91 53.0 23 0.17 2.7 of the Rockies. In Colorado, where the 8 0.91 38.7 24 0.15 2.1 material used for the oviposition data was 9 0.91 46.1 25 0.11 0 10 0.91 30.9 26 0.09 0 collected, it is a common butterfly of dry 11 0.91 30.6 27 0.09 0 open grasslands (Brown, Eff, and Rotger, 12 0.87 18.6 28 0.06 2.0 1957). It is univoltine; the larvae begin 13 0.83 26.3 29 0.04 0 winter diapause immediately upon hatch­ 14 0.72 16.1 30 0.02 0 15 0.68 14.3 31 0.02 0 ing. The larval foodplants are grasses. 16 0.64 9.5 32 0 0 Number of Eggs Laid Euphydryas editha lays the largest num­ Each component will be discussed in ber of eggs (731 per female) of the four turn, with attempts to demarcate the range butterflies compared in the figures, although of variation within the butterfly group, to females of Colias eurytheme are within the locate the position of Euphydryas editha same range with an expected number of within this range, and, where such discus­ 704. Some E. editha females lay as many sion may be profitable, to establish pos­ as 1200 eggs. This is the largest number sible life history and ecological correlates reported for any butterfly. One of the low­ of each component. est reproductive rates among butterflies is A brief description of the three other that of the tropical Heliconius erato, Fig­ species represented in the figures will be ure 1d, which lays only about 24 eggs per helpful in comparisons of oviposition pat­ female. terns. A reproductive rate as large as that of Heliconius erato (Nymphalidae: Nym­ E. editha allows an impressive power of phalinae) is a neotropical butterfly show­ increase. A few calculations quickly dem­ ing great geographic variation (Emsley, onstrate this. Assume that 90% larval 1964). The data used in this paper relate mortality is to be expected in natural pop­ to the Trinidad form. H. erato is conspic­ ulations, that there is a 1 : 1 sex ratio, and uously colored and has been shown to be further assume that a single mated female unpalatable to predators (Brower, Brower, founds a colony in a suitable area. In just and Collins, 1963). It is restrictive in its the second season after this single found­ choice of larval foodplants, being associated ing event the population would have an only with species of Passijlora. expected size of over 2600 adults (2' Colias eurytheme (Pieridae : Coliadinae), [(731/2) . 0.10]2 = 2672). the alfalfa butterfly, is now common over A high rate of increase is an important most of North America, although it was part of a good strategy for colonization; once restricted to the western portion.