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Butterfly conservation—The need for a captive breeding institute
Biological Conservation 25 (1983) 19-33
Butterfly Conservation The Need for a Captive Breeding Institute Ashley C. Morton Department of Biology, Building 44, The University, Southampton SO9 5NH, Great Britain
ABSTRACT There is increasing evidence that local invertebrate populations persist only because of oceasional immigration. Demands on land are so great that suites of reserves within the natural dispersal abilities of most speeies are unlikely to be obtained. Thus there may be little alternative to occasional reintroduction of stock if some species are to be preserved. Moreover, there may be occasions when a species is threatened with extinction due to destruction of its last habitats, and the absence of other suitable sites to which it could be transferred, In such cases there is a need to maintain stocks in captivity for use in future reintroductions. Indeed, this has been the approachJbllowed by vertebrate conservationists, where the ideal of habitat conservation is often prohibitively expensive. Recent methods of rearing butterflies on artificial diets have allowed costeffective production of large populations of butterflies and moths, even when their natural foodplant is unavailable. These populations may be considerably larger than their natural counterparts. Since it is more efficient to use resources to produce a number of species on one site, it is proposed that the maintenance of stocks of rare species be entrusted to a Captive Breeding Institute established for this purpose. Since the techniques employed have commercial potential in mass-production of species of economic importance, it is hoped that the Institute will be largely self-financing after its initialfoundation. In this manner resources will not be diverted from the essential work of habitat conservation.
INTRODUCTION The causes of extinction have been well-reviewed in several publications (e.g. Ziswiler, 1967; Fisher et al., 1969; Curry-Lindhal, 1972; Uetz & 19 Biol. Conserv. 0006-3207/83/0025-0019/$03.00 © Applied Science Publishers Ltd, England, 1983. Printed in Great Britain
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Johnson, 1974; Smith, 1976). There is general agreement that the most important cause is destruction of habitat. It has been estimated that world loss of habitat could be as much as 40 000 ha each day (Hahn, 1980). As their habitats become more fragmented, species occur as smaller, isolated populations which are increasingly at risk of extinction. However, there is little agreement as to the cause of the decline of such populations. Small isolated populations are often thought to experience a number of genetic problems which may lead to their final extinction. Random and possibly deleterious changes due to genetic drift are often invoked as possible causes of decline, although Berry (1971) maintains that such changes are unlikely to be of great significance. If one accepts a critical coefficient of inbreeding of 0.333 (where all gene frequencies are equally probable among the isolated populations) then it can be shown that only one immigrant every second generation is necessary to balance genetic drift (Wright, 1951). Bonnell & Selander (1974) suggest that genetic variation in isolated populations is reduced. This will make a population more responsive to changes in selection pressures; if these changes occur in both directions at random then population numbers may fluctuate more widely and the probability of random extinction is increased. However, there is evidence that variation is extremely large and resistant to loss. Moreover, a population with a primary poverty of variability seems to acquire more (Berry & Murphy, 1970). Increased inbreeding could have the effect of increasing the frequency of deleterious homozygous recessives, which may result in a loss of fertility and viability. This concept was suggested as an explanation for the decline of the large blue butterfly Maculinea arion eutyphron (Fruhst.) in Britain (Benham, 1973; Muggleton & Benham, 1975), but there is no evidence that such events occurred in this species (Thomas, 1977, 1980). Similarly, there was no increase in the proportion of ova which were inviable during the decline of the reintroduced population of Papilio machaon britannicus Seitz at Wicken Fen (Dempster & Hall, 1980). It is quite possible that physical isolation of colonies could lead to extinction due to factors largely unrelated to genetical considerations. It can be shown that extinction is a certainty for any organism to which there is an upper limit in numbers, if the time scale is infinite (Skellam, 1955). For a finite time scale, the probability of extinction varies with the number of individuals and their life-span. Populations that are composed of large numbers of highly inter-
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connected subpopulations may survive for many generations if the risk of extinction is sufficiently spread over the subpopulations. This does not mean that the subpopulations necessarily survive much longer than isolated populations. But within such a composite population, even a species with poor powers of dispersal will be able to repopulate a former site when conditions become favourable again. The more isolated the subpopulations, the more dispersal on a larger scale will be needed to spread the risk of extinction (Andrewartha & Birch, 1954; den Boer, 1968, 1971). Rare species will depend on immigration to a site for their survival there for even short periods of time. Moreover, if either the lognormal or the logarithmic distribution of species abundance is usual then, whatever the size of the site, there will always be something so rare as to have a high probability of random extinction. That stabilisation of numbers may be a result of 'spreading the risk' over a number of subpopulations has been demonstrated by Reddingius & den Boer (1970). More specifically, the concept simulates processes which occur in populations ofcarabid beetles (den Boer, 1981), and which are thought to occur in many butterfly populations (Ehrlich, 1965; Morton, 1978; Shapiro, 1978; Ehrlich et al., 1980). Local extinctions may be caused by periods of unfavourable weather when habitat suitability has also declined (Pollard, 1979; Dempster & Hall, 1980; Ehrlich et al., 1980; Thomas, 1980). They may also be brought about by parasites or disease, although this is less well documented. Ford (1976) observed two exterminations of Lycaena phlaeas (L.) by Apanteles cupreus Lyle during a period of about ten years. Such events are probably unpredictable, and may not occur during a short-term intensive study of a few sites. For example, as a result of a careful study of Ladoga camilla (L.) Pollard (1979) suggested that parasitism was relatively unimportant in this species. However, Shaw (1981) presents data which show that L. camilla is subjected to erratic but sometimes very high levels of parasitism. Populations that are reduced to very low levels by chance might be expected to show logistic growth and thus rapidly reach 'normal' density levels again. This argument is not always confirmed by observations. At low densities such populations are at the mercy of chance to recover again or die out (Milne, 1957, 1962; Klomp et al., 1964). Hooper (1971) has shown that a choice exists: either (i) the rare species are not conserved; (ii) their populations on a single isolated reserve must be very large; (iii) several sites within their normal dispersal distances must be conserved; or (iv) species are constantly reintroduced from
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artificially maintained populations. With a limited number of sites, the artificial maintenance and reintroduction of the rarest species may be a necessity. Conservationists are faced with the task of trying to preserve an increasing number of endangered species at a time when financial resources are becoming increasingly scarce. Under such circumstances, any conservation measures adopted must be cost-effective. The aim of this paper is to attempt to demonstrate that an economical and effective approach to butterfly conservation is to concentrate more on the maintenance in captivity of populations of endangered species. This will provide a short-term alternative to extinction if funds for habitat conservation and management are unavailable. To reduce duplication of effort, and concentrate expertise, it is proposed that a Captive Breeding Institute should be established as a matter of urgency.
A P P R O A C H E S TO C O N S E R V A T I O N T h e first step in conservation is usually some form of species conservation based on legislative action against hunting or collecting. The extent of protection afforded depends on the value society assigns to the species. This often rests upon its ability to provide market incentives such as game, tourism, or as an item for direct commercial exploitation. Once a market value is placed on a species, a powerful motivation exists for its preservation. Too often, attempts to enter a species into the market are opposed by protectionists who view such approaches as detrimental to the survival of the species (East, 1974). Restrictions on trade of endangered species may reduce incentive for management by some nations. Similarly, zoos may be unable to trade surplus stocks to other zoos, thus reducing the incentive for captive breeding. Certain types of laws also reduce the incentive to rear commercially important endangered species, such as alligators, a practice that would take the pressure off wild stocks. The effect of collecting on populations of butterflies is controversial due to lack of data, but the impact collectors have on populations will clearly depend on the biology of the species. Most authors suggest that collecting can only affect already weakened populations (Spooner, 1963; Muggleton, 1973; Gardiner, 1974; Pyle, 1976; J.A. Thomas, pers.
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comm.). Others suggest that collecting, particularly on a commercial scale, can cause extinctions (Sheldon, 1925; McLeod, 1979). Ford (1945) states that the final extinction of Lycaena dispar Haw. was almost certainly caused by over-collecting, and that a collector eliminated the introduced A raschn ia levana (L.) from Britain. Hayes ( 1981 ) suggests that removal of females may pose a greater threat in terms of population decline than many have chosen to believe. However, the proportion of the total population of some species, such as the purple emperor Apatura iris (L.) and black hairstreak Strymonidia pruni (L.), which is at risk of collection at any one time is very small (J. A. Thomas, pers. comm.). Collectors are unlikely to have a significant effect on such species. Others, such as the heath fritillary Mellicta athalia Rott., are much more vulnerable and require protection. There can be little doubt that collecting does nothing to enhance the survival of rare species, and thus in many cases the protective legislation seems fully justified. But it is the question of the proportion of available resources that should be devoted to enforcement, for example by providing wardens during the collecting season, which is open to debate. If collectors are unlikely to have much impact, as seems to be the case with A. iris, such funds may be better spent on other forms of conservation. It is evident that protective legislation alone is insufficient to prevent extinctions, since a number of 'protected' species have become extinct, including butterflies. Such laws are often supplemented by the establishment of refuges. Since ecosystems are dynamic, some management is usually necessary to maintain the desired habitat at the correct stage of natural succession. Only in recent years have sufficient data been made available to allow the development of management plans for butterflies based on ecological principles rather than hunches (Ehrlich, 1965; Duffey, 1968; Brussard & Ehrlich, 1970; Dempster, 1971 ; Thomas, 1974, 1980; Ehrlich et al., 1975; Pollard, 1979; Arnold, 1980; Dempster & Hall, 1980). However, there seems a real possibility that some forms will become extinct before the management plans have had time to produce results (Arnold et al., 1980). Very few vertebrate protection programmes have tackled the problems of re-establishing or creating new habitat. The areas required would be enormous and the costs prohibitive, even if ecological data were available to allow the formation of management plans. As an alternative, vertebrate conservation has concentrated on captive breeding and maintenance of stock for future reintroduction when habitats can be
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made available. Thus zoos are now important banks of genetic reserves rather than mere collections of show pieces. Early work in this field suffered from neglect of genetical aspects of stock maintenance. Few animals could be kept, and the resulting inbreeding wag further accentuated by poor management of crosses. The resulting stock was therefore often inferior to wild forms, and many reintroductions failed. Other attempts had even more serious consequences due to introductions into areas previously or still occupied by different subspecies (Clarke, 1954; Chapman & Morgan, 1973). However, several well-known mammals, such as the European bison Bison bonasus and P6re David's deer Elaphurus davidianus, exist only because of captive breeding stocks. Vertebrate conservationists are now much more alert to the problems of inbreeding, and the maintenance of captive stocks and future reintroduction are the 'double task' of the conservationist. This position was clearly stated by both Richard Fitter (honorary secretary of the Fauna Preservation Society) and Sir Peter Scott (Chairman of the Survival Service Commission of the International Union for the Conservation of Nature) at the World Conference III on Breeding Endangered Species in Captivity, in San Diego, 1980. The possibility of butterfly conservation following the example of vertebrate conservation in this respect has been largely ignored. Breeding and introductions have generally been regarded as a last resort. For example, Pyle (1976) stated that such measures are extreme and will not form a significant part of the programme of the Xerces Society in the USA. In Britain, the Committee for the Protection of British Lepidoptera was formed by the Council of the Royal Entomological Society in 1925. It was intended to protect rare and distinctive species in their existing haunts and to introduce butterflies 'into suitable areas where they are at present absent and where they will be protected' (Sheldon, 1925). Attempts to introduce species into areas where they had previously been absent aroused a great deal of controversy. Finally, it was generally agreed that transplanting was only justified in two circumstances. The first was where the species had become locally extinct. It was essential, however, to know the source of the new stock and to record the introduction in a reputable scientific journal. The second occasion was when a rare species was threatened with extinction due to the destruction of its habitat. However, it has been argued above that there may be no alternative to occasional reintroduction of stock on to reserves. Given that reintroductions are desirable, at least in some cases, one is
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still left to question the effectiveness of such measures. Although it would be a mistake to underestimate the knowledge required to ensure a successful reintroduction, there is little doubt that some introductions are successful. Where there is failure, it is often caused by selecting sites where the habitat has become unsuitable. The earlier one attempts reintroduction after a species becomes extinct, the greater the chances of success--especially if management programmes can increase the carrying capacity of the site. The large copper butterfly Lycaena dispar Haw. batavus Obth. was introduced into part of Woodwalton Fen in 1927, to replace Lycaena dispar Haw. which became extinct during the mid- 19th century. The trials were considered a success, although the number of butterflies was reduced by bird and small mammal predation on the larvae. However, continued success of the introduction seems to depend upon protecting some of the larvae by caging them each year (Duffey, 1968). An attempt at re-establishing the swallowtail butterfly Papilio machaon britannicus at Wicken Fen in 1975 failed when the population crashed the following year, despite promising early results, and became extinct in 1979 (Dempster & Hall, 1980). However, during that time it was established that the habitat no longer contained sufficient larval foodplant to support a viable population. By 1977 it was thought that only five adult female large blue butterflies Maculinea arion eutyphron remained, and that two of these had failed to mate. It was therefore decided to rear the adult, egg and early larval stages of the 1978 population in captivity (Thomas, 1980). Unfortunately, adults produced by the breeding programme in 1979 failed to pair in captivity and the population became extinct. It seems evident that the last colony was lost because the site, though well maintained, was too small to support a population large enough to withstand chance effects (Thomas, 1980). In contrast to the above failures, which seem to have been largely due to the sites being ecologically unsuitable or too small, there have been some notable successes. The heath fritillary Mellicta athalia became extinct in Essex about 1890. In 1925 it was reintroduced in the Hadleigh Woods and the resulting colony flourished for over 40 years (Luckens, 1980). Stock from this introduced colony (Ford, 1945), or from Blean Woods in Kent (Newman, 1954), was used to re-establish this species in Abbots Wood, Sussex, in 1935. This colony survived for about 20 years, until woodland management procedures made the habitat unsuitable.
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All known extinctions of the black hairstreak Strymonidia pruni have been caused by destruction of its breeding areas (Thomas, 1974). This species is very sedentary and extremely slow to colonise new habitats. A number of successful introductions have occurred both within and beyond its natural distribution. The black hairstreak disappeared from Warboys Wood between 1893 and 1917, but stock from Monks Wood was used to re-establish the insect there. This was fortunate, because Monks Wood was subjected to clearance during the First World War, and S. pruni was extirpated. When the foodplant had recovered in the burnt areas of Monks Wood, stock of S. pruni from Warboys Wood was used to re-establish this species in Monks Wood in about 1922. This reintroduction was also successful, and by 1942 Monks Wood was again the metropolis for this species (Leeds, 1942, 1953, cited in Thomas, 1974). The range of S. pruni was greatly extended in 1952 by the introduction of less than 20 adults into the Cranleigh area in Surrey, from ova collected in Oundle (Collier, 1959, 1960, 1962). Although this colony became extinct when the wood was clearfelled in 1961, the butterfly had spread to a nearby wood, and was found on a model site in 1975. By 1978 this site supported the largest colony that has been known in Britain for many years (Thomas, 1980). The wood white butterfly Leptidea sinapis (L.) has been the subject of several successful introductions in recent years, often in areas with no previous history of the species (Warren, 1981). The continental vanessid Araschnia levana was introduced into Britain in about 1912, and the colonies increased in numbers for several years, until apparently exterminated by a collector (Ford, 1945). Introductions of the Glanville fritillary Melitaea cinxia (L.) have also been claimed (Watson, 1979), and there are doubtless other British examples not on record. In the USA, transfer of eggs and larvae of Euphydryas gillettii Barnes from Wyoming have resulted in the establishment of at least one Colorado population (Holdren & Ehrlich, 1981). Reintroductions have been proposed for Parnassius apollo frankenbergei Slaby (Palik, 1980), and are being implemented for Lysandra bellargus (L.) and the endangered Californian riodinine Apodemia mormo langei Comstock (Arnold et al., 1980). Traditionally, the costs of reintroduction have been very high. This is in part due to the cost of preparing and maintaining sites, but the cost of providing stock is not inconsiderable. However, with the newer methods of rearing butterflies on artificial diets (Singh, 1977; Morton, 1981),
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captive breeding may be highly cost-effective. There is little reason to suppose that funds for conservation will be high on the list of priorities during the present economic crisis. This situation considerably reduces the potential for effective habitat conservation. Combined with the possible need for introductions in any case, these circumstances dictate the need to establish breeding stocks of threatened species as soon as possible. There will then be an alternative to extinction simply because funds were not available to protect or manage habitats. With this in mind, the first Captive Breeding Institute was provisionally formed as an extension of the Lepidoptera Research Foundation (Morton et al., 1980) in the USA.
OBJECTIVES OF THE INSTITUTE It is more efficient to rear a large number of species on one site, using suitably trained and experienced staff, than to leave production of single species to workers in different laboratories. Moreover, this approach does not oblige the field ecologist working with endangered species to invest time and resources in routine laboratory tasks. It is therefore suggested that the majority of livestock production programmes be entrusted to the Institute, which will then 'spread the risk' of accidental losses over a number of production facilities. The Institute will concentrate on the maintenance of butterfly populations, with emphasis on low cost and quality control. In the main, species will be reared on artificial diets by methods already established (Arnold et al., 1980; Morton, 1981). These could allow as many as 20 species, each with population of several thousands, to be maintained by a staff of three--one specialist and two technicians. There will also be a need for some plant production to provide material for ovipositing females. A small garden plot and heated greenhouse would provide material for a wide range of temperate and tropical species. There will be a need for continued research into rearing on diets, and also other aspects which enhance the production of insects, such as stimuli for pairing and ovipositing, pathology and microbiology. It is also anticipated that potential genetic problems will be monitored by behavioural studies and gel electrophoresis. The same facilities are required for mass-production of insects of
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commercial importance. It is therefore anticipated that such commercial activities will help to fund the work with endangered species, and may eventually also support ecological studies on wild populations. Work will also have to be conducted with common species of no commercial interest. These will be used as surrogates to enable development of rearing techniques for closely related endangered species, so that such insects are not put at risk by rearing experiments. There is no reason why rare species for which artificial diets are not yet available could not also be maintained by the Institute, using more traditional techniques. This would, however, prove much more costly and only small numbers could be maintained.
PROPOSED F U N D I N G OF THE INSTITUTE The aim of conservation is to preserve organisms in their natural habitats. It should be emphasised that the Captive Breeding Institute is not an alternative to habitat conservation, but a necessary partner to it. It is therefore important that funding should not be secured at the cost of reduced financing of essential field studies. Although some initial funding is expected to be from conservation bodies and private donations, it is felt that the Institute will function most effectively if it is largely self-financing. This might be achieved in several ways. First, it is proposed to undertake mass-production of species of economic importance. Aspects of biological control are well developed in the USA and the provisional Institute is at present funded by proceeds from mass-production of pink bollworm adults Pectinophora gossypiella Saunders for sterile-release and Heliothis virescens Fab. for pheromone studies, via support from Agresearch Inc., of Los Angeles and Phoenix. Similar markets are poorly developed in Europe at present, but the possibility of large-scale silk production is being examined. Funds may also be available from small-scale production. A number of species which may be reared on diets are ideal for educational work in schools and universities. Others are required for specific research interests, such as Helieonius spp. Interest has also been expressed by some butterfly farms which exhibit live specimens of tropical species, and these could be a major source of funds. It should be emphasised that there is no intention of supplying livestock to collectors or deadstock to anyone.
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Even if such activities were permitted by law, no rare species will form part of the commercial operations of the Institute. The final main source of funding does concern the rare species, where it is hoped that the activities of the Institute will be supported by rearing contracts from specific conservation bodies. However, if funds are available from any other sources such rearing will be undertaken without charge. Indeed, any 'profits' made by the Institutes will be wholly used to maintain further populations, to support research, and to assist with the costs of managing or securing habitats. Further details of the proposals for funding and organisation are available from the author or the Lepidoptera Research Foundation.
CONCLUSIONS There can be little doubt that if funds for conservation are not increased an alarming number of butterflies may become extinct due to loss of suitable habitat. Further, even if sufficient funds are available there may be chance losses of local populations. There is a need to re-examine our attitudes to reintroductions, and possibly populations will benefit if we adopt the approaches of vertebrate conservationists. The most costeffective way to do this will be to fund the establishment of a Captive Breeding Institute in order to ensure survival in captivity and supplies of stocks for reintroduction.
A C K N O W L E D G E M ENTS Thanks are due to Dr R. H. T. Mattoni and Agresearch Inc. for funding my visits to the USA, and providing research facilities for the development of artificial diets for butterflies. Our enthusiastic discussions were greatly encouraged by Dr R. A. Arnold, who assisted at the birth of the Institute. Agresearch Inc. and the Office of Endangered Species/United States Fish and Wildlife Service provided funds for the Institute's work with Apodemia mormo langei. Whilst retaining responsibility for views and opinions expressed in this paper, it is a great pleasure to thank the following for their enthusiastic comments on an earlier discussion document: Professors T o m Eisner and Eric Lees, Drs Jack Dempster,
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John Heath, Michael Morris, Ernie Pollard, Claude Rivers, Jeremy Thomas, Martin Warren and Richard White.
REFERENCES Andrewartha, H. G. & Birch, L. C. (1954). The distribution and abundance of animals. Chicago, Chicago University Press. Arnold, R. A. (1980). Ecological studies of six endangered butterflies (Lepidoptera: Lycaenidae); island biogeography, patch dynamics, and the design of habitat preserves. PhD thesis, University of California, Berkeley. Arnold, R. A., Morton, A. C. & Mattoni, R. H. T. (1980). A captive breeding program for Apodemia mormo langei Comstock (Lepidoptera." Lycaenidae, Riodininae). Proposal prepared for OES/USFWS Los Angeles, Agresearch Inc. Benham, B. R. (1973). The decline (and fall?) of the large blue butterfly. Bull. amat. Ent. Soc., 32, 88-94. Berry, R. J. (1971). Conservation aspects of the genetical constitution of populations. In The scientific management of animal and plant communities for conservation, ed. by E. Duffey and A.S. Watt, 177-206. Oxford, Blackwell. Berry, R. J. & Murphy, H. M. (1970). Biochemical genetics of an island population of the house mouse. Proc. R. Soc. B, 176, 87-103. Bonnell, M. L. & Selander, R. K. (1974). Elephant seals: Genetic variation and near extinction. Science, N.Y., 184, 908-9. Brussard, P. F. & Ehrlich, P. R. (1970). The population structure of Erebia epipsodea (Lepidoptera: Satyrinae). Ecology, 51, 119-29. Chapman, J. A. & Morgan, R. P. (1973). Systematic status of the cottontail complex in western Maryland and nearby West Virginia. Wildl. Monogr., 36. Clarke, C. H. D. (1954). The bob-white quail in Ontario. Tech. Bull. Fish & Wildl. Ser., No. 2. Collier, A. E. (1959). A forgotten discord: the problem of redundancy. Ent. Rec., 71, 118-9. Collier, A. E. (1960). Butterflies in partial eclipse. Ent. Rec., 72, 253-4. Collier, A. E. (1962). Butterflies in the Cranleigh district, 1961. Ent. Rec., 74, 45-7. Curry-Lindhal, K. (1972). Let them live. New York, Murrow. Dempster, J. P. (1971). The population ecology of the cinnabar moth, Tyria jacobaea L. (Lepidoptera, Arctiidae). Oecologia, 7, 26-7. Dempster, J. P. & Hall, M. L. (1980). An attempt at re-establishing the swallowtail butterfly at Wicken Fen. Ecol. Ent., 5, 327-34. den Boer, P. J. (1968). Spreading of risk and stabilization of animal numbers. Acta biotheor., 18, 165-94.
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den Boer, P. J. (1970). On the significance of dispersal power for populations of carabid-beetles (Coleoptera, Carabidae). Oecologia, 4, 1-28. den Boer, P. J. (1971). Stabilization of animal numbers and the heterogeneity of the environment: The problem of the persistence of sparse populations. In Dynamics of populations, ed. by P. J. den Boer and G. R. Gradwell, 77-97. Wageningen, Centre for Agricultural Publishing and Documentation. den Boer, P. J. (1981). On the survival of populations in a heterogenous and variable environment. Oecologia, 50, 39-53. Duffey, E. (I 968). Ecological studies on the large copper butterfly Lycaena dispar Haw. batavus Obth. at Woodwalton Fen National Nature Reserve, Huntingdonshire. J. appl. Ecol., 5, 69-96. East, B. (1974). The endangered species bandwagon. Outdoor Life, 154(5), 51-3, 108-13. Ehrlich, P. R. (1965). The population biology of the butterfly Euphydryas editha, II. The Jasper Ridge colony. Evolution, 19, 327-36. Ehrlich, P. R., Murphy, D. D., Singer, M. C., Sherwood, C. B., White, R. R. & Brown, I.L. (1980). Extinction, reduction, stability and increase: the responses of checkerspot butterfly (Euphydryas) populations to the California drought. Oecologia, 46, 101-5. Ehrlich, P. R., White, R. R., Singer, M. C., McKechnie, S. W. & Gilbert, L. E. (1975). Checkerspot butterflies: A historical perspective. Science, N.Y., 188, 221-8. Fisher, J., Simon, N. & Vincent, J. (1969). Wildlife in danger. New York, Viking. Ford, E. B. (1945). Butterflies. London, Collins. Ford, R. L. E. (1976). The influence of the microgasterini on the populations of British Rhopalocera (Hymenoptera: Braconidae). Ent. Gaz., 27, 205-10. Gardiner, B. O. C. (1974). On vanishing butterflies. Bull. amat. Ent. Soc., 33, 145-51. Hahn, E. (1980). Eleventh hour. The New Yorker, September 1st, 1980, 37-69. Hayes, J. L. (1981). The population ecology of a natural population of the Pierid butterfly Colias alexandra. Oecologia, 49, 188-200. Holdren, C. E. & Ehrlich, P. R. (1981). Long range dispersal in checkerspot butterflies: Transplant experiments with Euphydryas gillettii. Oecologia, 50, 125-9. Hooper, M. D. (1971). The size and surroundings of nature reserves. In The scientific management of animal and plant communities for conservation, ed. by E. Duffey and A. S. Watt, 555-61. Oxford, Blackwell. Klomp, H., van Montfort, M. A. J. & Tammes, P. M. L., (1964). Sexual reproduction and underpopulation. Arch. n~erl, zool., 16, 105-10. Luckens, C. J. (1980). The heath fritillary, Mellicta athalia Rott. in Britain: Notes on distribution and ecology. Ent. Rec. J. Var., 92, 229-34. McLeod, L. (1979). A ban on collecting Lepidoptera in the Department of the Alpes de Haute-Provence, France. Ent. Rec. J. Var., 91, 37-41. Milne, A. (1957). Theories on natural control of insect populations. Cold Spring Harb. Symp. quant. Biol., 25, 253-71.
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Milne, A. (1962). A theory of natural control of insect populations. J. theor. Biol., 3, 19-50. Morton, A. C. (1978). Isolation as a factor responsible for the decline of the large blue butterfly Maculinea arion (L.) in Great Britain. Ent. mon. Mag., ll4, 247-9. Morton, A. C. (1981). Rearing butterflies on artificial diets. J. Res. Lep., 18, 221-7. Morton, A. C., Mattoni, R. H. T. & Arnold, R. A. (1980). The Captive Breeding Institute. Los Angeles, Agresearch Inc. Muggleton, J. (1973). Some aspects of the history and ecology of blue butterflies in the Cotswolds. Proc. Brit. ent. nat. Hist. Soc., 6, 77-84. Muggleton, J. & Benham, B. R. (1975). Isolation and the decline of the large blue butterfly (Maculinea arion) in Great Britain. Biol. Conserv., 7, 119-28. Newman, L. H. (1954). Butterfly farmer. London, Country Book Club. Palik, E. (1980). The protection and reintroduction in Poland of Parnassius apollo Linnaeus (Papilionidae). Nora lepid., 2, 163-4. Pollard, E. (1979). Population ecology and change in range of the white admiral butterfly Ladoga camilla L. in England. Ecol. Ent., 4, 61-74. Pyle, R. M. (1976). Conservation of Lepidoptera in the United States. Biol. Conserv., 9, 55-75. Reddingius, J. & den Boer, P. J. (1970). Simulation experiments illustrating stabilisation of animal numbers by spreading of risk. Oecologia, 5, 240 84. Shapiro, A. M. (1978). Weather and lability of breeding populations of the checkered white butterfly, Pieris protodice Boisduval & LeConte. J. Res. Lep., 17, 1-23. Shaw, M. R. (1981). Parasitism by Hymenoptera of larvae of the white admiral butterfly, Ladoga camilla (L.), in England. Ecol. Ent., 6, 333-5. Sheldon, W. G. (1925). The destruction of British butterflies. Entomologist, 58, 105 12. Singh, P. (1977). Artificial diets for insects, mites and spiders. New York, IFI/ Plenum. Skellam, J. G. (1955). The mathematical approach to population dynamics. In The numbers of man and animals, ed. by J. B. Cragg and N. W. Pirie, 31-45. London, Oliver & Boyd. Smith, R. L. (1976). Ecological genesis of endangered species: The philosophy of preservation. Ann. Rev. Ecol. Syst., 7, 33-55. Spooner, G. M. (1963). On causes of the decline of Maculinea arion L. (Lep., Lycaenidae) in Britain. Entomologist, 96, 199-210. Thomas, J. A. (1974). Factors influencing the numbers and distribution of the brown hairstreak, Thecla betulae L. ( Lepidoptera, L ycaenidae) and the black hairstreak, Strymonidia pruni L. (Lepidoptera, Lycaenidae). PhD thesis, University of Leicester. Thomas, J. A. (1977). The ecology of the large blue butterfly. Institute of Terrestrial Ecology, Annual Report, 1976, 25-7. London, HMSO. Thomas, J. A. (1980). The extinction of the large blue and the conservation of the
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black hairstreak (a contrast of failure and success). Institute of Terrestrial Ecology, Annual Report, 1979, 19-23. London, HMSO. Uetz, G. & Johnson, D. L. (1974). Breaking the web. Environment, 16, 31-9. Warren, M. (1981). The ecology of the wood white butterfly Leptidea sinapis L. (Lep. Pieridae). PhD thesis, University of Cambridge. Watson, L. A. (1979). Unusual food plant of Melitaea cinxia L. Ent. Rec. J. Vat., 91,233. Wright, S. (1951). The genetical structure of populations. Ann. Eugen., 15, 323-54. Ziswiler, V. (1967). Extinct and vanishing animals. New York, Springer.
Butterfly Conservation The Need for a Captive Breeding Institute Ashley C. Morton Department of Biology, Building 44, The University, Southampton SO9 5NH, Great Britain
ABSTRACT There is increasing evidence that local invertebrate populations persist only because of oceasional immigration. Demands on land are so great that suites of reserves within the natural dispersal abilities of most speeies are unlikely to be obtained. Thus there may be little alternative to occasional reintroduction of stock if some species are to be preserved. Moreover, there may be occasions when a species is threatened with extinction due to destruction of its last habitats, and the absence of other suitable sites to which it could be transferred, In such cases there is a need to maintain stocks in captivity for use in future reintroductions. Indeed, this has been the approachJbllowed by vertebrate conservationists, where the ideal of habitat conservation is often prohibitively expensive. Recent methods of rearing butterflies on artificial diets have allowed costeffective production of large populations of butterflies and moths, even when their natural foodplant is unavailable. These populations may be considerably larger than their natural counterparts. Since it is more efficient to use resources to produce a number of species on one site, it is proposed that the maintenance of stocks of rare species be entrusted to a Captive Breeding Institute established for this purpose. Since the techniques employed have commercial potential in mass-production of species of economic importance, it is hoped that the Institute will be largely self-financing after its initialfoundation. In this manner resources will not be diverted from the essential work of habitat conservation.
INTRODUCTION The causes of extinction have been well-reviewed in several publications (e.g. Ziswiler, 1967; Fisher et al., 1969; Curry-Lindhal, 1972; Uetz & 19 Biol. Conserv. 0006-3207/83/0025-0019/$03.00 © Applied Science Publishers Ltd, England, 1983. Printed in Great Britain
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Johnson, 1974; Smith, 1976). There is general agreement that the most important cause is destruction of habitat. It has been estimated that world loss of habitat could be as much as 40 000 ha each day (Hahn, 1980). As their habitats become more fragmented, species occur as smaller, isolated populations which are increasingly at risk of extinction. However, there is little agreement as to the cause of the decline of such populations. Small isolated populations are often thought to experience a number of genetic problems which may lead to their final extinction. Random and possibly deleterious changes due to genetic drift are often invoked as possible causes of decline, although Berry (1971) maintains that such changes are unlikely to be of great significance. If one accepts a critical coefficient of inbreeding of 0.333 (where all gene frequencies are equally probable among the isolated populations) then it can be shown that only one immigrant every second generation is necessary to balance genetic drift (Wright, 1951). Bonnell & Selander (1974) suggest that genetic variation in isolated populations is reduced. This will make a population more responsive to changes in selection pressures; if these changes occur in both directions at random then population numbers may fluctuate more widely and the probability of random extinction is increased. However, there is evidence that variation is extremely large and resistant to loss. Moreover, a population with a primary poverty of variability seems to acquire more (Berry & Murphy, 1970). Increased inbreeding could have the effect of increasing the frequency of deleterious homozygous recessives, which may result in a loss of fertility and viability. This concept was suggested as an explanation for the decline of the large blue butterfly Maculinea arion eutyphron (Fruhst.) in Britain (Benham, 1973; Muggleton & Benham, 1975), but there is no evidence that such events occurred in this species (Thomas, 1977, 1980). Similarly, there was no increase in the proportion of ova which were inviable during the decline of the reintroduced population of Papilio machaon britannicus Seitz at Wicken Fen (Dempster & Hall, 1980). It is quite possible that physical isolation of colonies could lead to extinction due to factors largely unrelated to genetical considerations. It can be shown that extinction is a certainty for any organism to which there is an upper limit in numbers, if the time scale is infinite (Skellam, 1955). For a finite time scale, the probability of extinction varies with the number of individuals and their life-span. Populations that are composed of large numbers of highly inter-
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connected subpopulations may survive for many generations if the risk of extinction is sufficiently spread over the subpopulations. This does not mean that the subpopulations necessarily survive much longer than isolated populations. But within such a composite population, even a species with poor powers of dispersal will be able to repopulate a former site when conditions become favourable again. The more isolated the subpopulations, the more dispersal on a larger scale will be needed to spread the risk of extinction (Andrewartha & Birch, 1954; den Boer, 1968, 1971). Rare species will depend on immigration to a site for their survival there for even short periods of time. Moreover, if either the lognormal or the logarithmic distribution of species abundance is usual then, whatever the size of the site, there will always be something so rare as to have a high probability of random extinction. That stabilisation of numbers may be a result of 'spreading the risk' over a number of subpopulations has been demonstrated by Reddingius & den Boer (1970). More specifically, the concept simulates processes which occur in populations ofcarabid beetles (den Boer, 1981), and which are thought to occur in many butterfly populations (Ehrlich, 1965; Morton, 1978; Shapiro, 1978; Ehrlich et al., 1980). Local extinctions may be caused by periods of unfavourable weather when habitat suitability has also declined (Pollard, 1979; Dempster & Hall, 1980; Ehrlich et al., 1980; Thomas, 1980). They may also be brought about by parasites or disease, although this is less well documented. Ford (1976) observed two exterminations of Lycaena phlaeas (L.) by Apanteles cupreus Lyle during a period of about ten years. Such events are probably unpredictable, and may not occur during a short-term intensive study of a few sites. For example, as a result of a careful study of Ladoga camilla (L.) Pollard (1979) suggested that parasitism was relatively unimportant in this species. However, Shaw (1981) presents data which show that L. camilla is subjected to erratic but sometimes very high levels of parasitism. Populations that are reduced to very low levels by chance might be expected to show logistic growth and thus rapidly reach 'normal' density levels again. This argument is not always confirmed by observations. At low densities such populations are at the mercy of chance to recover again or die out (Milne, 1957, 1962; Klomp et al., 1964). Hooper (1971) has shown that a choice exists: either (i) the rare species are not conserved; (ii) their populations on a single isolated reserve must be very large; (iii) several sites within their normal dispersal distances must be conserved; or (iv) species are constantly reintroduced from
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artificially maintained populations. With a limited number of sites, the artificial maintenance and reintroduction of the rarest species may be a necessity. Conservationists are faced with the task of trying to preserve an increasing number of endangered species at a time when financial resources are becoming increasingly scarce. Under such circumstances, any conservation measures adopted must be cost-effective. The aim of this paper is to attempt to demonstrate that an economical and effective approach to butterfly conservation is to concentrate more on the maintenance in captivity of populations of endangered species. This will provide a short-term alternative to extinction if funds for habitat conservation and management are unavailable. To reduce duplication of effort, and concentrate expertise, it is proposed that a Captive Breeding Institute should be established as a matter of urgency.
A P P R O A C H E S TO C O N S E R V A T I O N T h e first step in conservation is usually some form of species conservation based on legislative action against hunting or collecting. The extent of protection afforded depends on the value society assigns to the species. This often rests upon its ability to provide market incentives such as game, tourism, or as an item for direct commercial exploitation. Once a market value is placed on a species, a powerful motivation exists for its preservation. Too often, attempts to enter a species into the market are opposed by protectionists who view such approaches as detrimental to the survival of the species (East, 1974). Restrictions on trade of endangered species may reduce incentive for management by some nations. Similarly, zoos may be unable to trade surplus stocks to other zoos, thus reducing the incentive for captive breeding. Certain types of laws also reduce the incentive to rear commercially important endangered species, such as alligators, a practice that would take the pressure off wild stocks. The effect of collecting on populations of butterflies is controversial due to lack of data, but the impact collectors have on populations will clearly depend on the biology of the species. Most authors suggest that collecting can only affect already weakened populations (Spooner, 1963; Muggleton, 1973; Gardiner, 1974; Pyle, 1976; J.A. Thomas, pers.
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comm.). Others suggest that collecting, particularly on a commercial scale, can cause extinctions (Sheldon, 1925; McLeod, 1979). Ford (1945) states that the final extinction of Lycaena dispar Haw. was almost certainly caused by over-collecting, and that a collector eliminated the introduced A raschn ia levana (L.) from Britain. Hayes ( 1981 ) suggests that removal of females may pose a greater threat in terms of population decline than many have chosen to believe. However, the proportion of the total population of some species, such as the purple emperor Apatura iris (L.) and black hairstreak Strymonidia pruni (L.), which is at risk of collection at any one time is very small (J. A. Thomas, pers. comm.). Collectors are unlikely to have a significant effect on such species. Others, such as the heath fritillary Mellicta athalia Rott., are much more vulnerable and require protection. There can be little doubt that collecting does nothing to enhance the survival of rare species, and thus in many cases the protective legislation seems fully justified. But it is the question of the proportion of available resources that should be devoted to enforcement, for example by providing wardens during the collecting season, which is open to debate. If collectors are unlikely to have much impact, as seems to be the case with A. iris, such funds may be better spent on other forms of conservation. It is evident that protective legislation alone is insufficient to prevent extinctions, since a number of 'protected' species have become extinct, including butterflies. Such laws are often supplemented by the establishment of refuges. Since ecosystems are dynamic, some management is usually necessary to maintain the desired habitat at the correct stage of natural succession. Only in recent years have sufficient data been made available to allow the development of management plans for butterflies based on ecological principles rather than hunches (Ehrlich, 1965; Duffey, 1968; Brussard & Ehrlich, 1970; Dempster, 1971 ; Thomas, 1974, 1980; Ehrlich et al., 1975; Pollard, 1979; Arnold, 1980; Dempster & Hall, 1980). However, there seems a real possibility that some forms will become extinct before the management plans have had time to produce results (Arnold et al., 1980). Very few vertebrate protection programmes have tackled the problems of re-establishing or creating new habitat. The areas required would be enormous and the costs prohibitive, even if ecological data were available to allow the formation of management plans. As an alternative, vertebrate conservation has concentrated on captive breeding and maintenance of stock for future reintroduction when habitats can be
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made available. Thus zoos are now important banks of genetic reserves rather than mere collections of show pieces. Early work in this field suffered from neglect of genetical aspects of stock maintenance. Few animals could be kept, and the resulting inbreeding wag further accentuated by poor management of crosses. The resulting stock was therefore often inferior to wild forms, and many reintroductions failed. Other attempts had even more serious consequences due to introductions into areas previously or still occupied by different subspecies (Clarke, 1954; Chapman & Morgan, 1973). However, several well-known mammals, such as the European bison Bison bonasus and P6re David's deer Elaphurus davidianus, exist only because of captive breeding stocks. Vertebrate conservationists are now much more alert to the problems of inbreeding, and the maintenance of captive stocks and future reintroduction are the 'double task' of the conservationist. This position was clearly stated by both Richard Fitter (honorary secretary of the Fauna Preservation Society) and Sir Peter Scott (Chairman of the Survival Service Commission of the International Union for the Conservation of Nature) at the World Conference III on Breeding Endangered Species in Captivity, in San Diego, 1980. The possibility of butterfly conservation following the example of vertebrate conservation in this respect has been largely ignored. Breeding and introductions have generally been regarded as a last resort. For example, Pyle (1976) stated that such measures are extreme and will not form a significant part of the programme of the Xerces Society in the USA. In Britain, the Committee for the Protection of British Lepidoptera was formed by the Council of the Royal Entomological Society in 1925. It was intended to protect rare and distinctive species in their existing haunts and to introduce butterflies 'into suitable areas where they are at present absent and where they will be protected' (Sheldon, 1925). Attempts to introduce species into areas where they had previously been absent aroused a great deal of controversy. Finally, it was generally agreed that transplanting was only justified in two circumstances. The first was where the species had become locally extinct. It was essential, however, to know the source of the new stock and to record the introduction in a reputable scientific journal. The second occasion was when a rare species was threatened with extinction due to the destruction of its habitat. However, it has been argued above that there may be no alternative to occasional reintroduction of stock on to reserves. Given that reintroductions are desirable, at least in some cases, one is
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still left to question the effectiveness of such measures. Although it would be a mistake to underestimate the knowledge required to ensure a successful reintroduction, there is little doubt that some introductions are successful. Where there is failure, it is often caused by selecting sites where the habitat has become unsuitable. The earlier one attempts reintroduction after a species becomes extinct, the greater the chances of success--especially if management programmes can increase the carrying capacity of the site. The large copper butterfly Lycaena dispar Haw. batavus Obth. was introduced into part of Woodwalton Fen in 1927, to replace Lycaena dispar Haw. which became extinct during the mid- 19th century. The trials were considered a success, although the number of butterflies was reduced by bird and small mammal predation on the larvae. However, continued success of the introduction seems to depend upon protecting some of the larvae by caging them each year (Duffey, 1968). An attempt at re-establishing the swallowtail butterfly Papilio machaon britannicus at Wicken Fen in 1975 failed when the population crashed the following year, despite promising early results, and became extinct in 1979 (Dempster & Hall, 1980). However, during that time it was established that the habitat no longer contained sufficient larval foodplant to support a viable population. By 1977 it was thought that only five adult female large blue butterflies Maculinea arion eutyphron remained, and that two of these had failed to mate. It was therefore decided to rear the adult, egg and early larval stages of the 1978 population in captivity (Thomas, 1980). Unfortunately, adults produced by the breeding programme in 1979 failed to pair in captivity and the population became extinct. It seems evident that the last colony was lost because the site, though well maintained, was too small to support a population large enough to withstand chance effects (Thomas, 1980). In contrast to the above failures, which seem to have been largely due to the sites being ecologically unsuitable or too small, there have been some notable successes. The heath fritillary Mellicta athalia became extinct in Essex about 1890. In 1925 it was reintroduced in the Hadleigh Woods and the resulting colony flourished for over 40 years (Luckens, 1980). Stock from this introduced colony (Ford, 1945), or from Blean Woods in Kent (Newman, 1954), was used to re-establish this species in Abbots Wood, Sussex, in 1935. This colony survived for about 20 years, until woodland management procedures made the habitat unsuitable.
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All known extinctions of the black hairstreak Strymonidia pruni have been caused by destruction of its breeding areas (Thomas, 1974). This species is very sedentary and extremely slow to colonise new habitats. A number of successful introductions have occurred both within and beyond its natural distribution. The black hairstreak disappeared from Warboys Wood between 1893 and 1917, but stock from Monks Wood was used to re-establish the insect there. This was fortunate, because Monks Wood was subjected to clearance during the First World War, and S. pruni was extirpated. When the foodplant had recovered in the burnt areas of Monks Wood, stock of S. pruni from Warboys Wood was used to re-establish this species in Monks Wood in about 1922. This reintroduction was also successful, and by 1942 Monks Wood was again the metropolis for this species (Leeds, 1942, 1953, cited in Thomas, 1974). The range of S. pruni was greatly extended in 1952 by the introduction of less than 20 adults into the Cranleigh area in Surrey, from ova collected in Oundle (Collier, 1959, 1960, 1962). Although this colony became extinct when the wood was clearfelled in 1961, the butterfly had spread to a nearby wood, and was found on a model site in 1975. By 1978 this site supported the largest colony that has been known in Britain for many years (Thomas, 1980). The wood white butterfly Leptidea sinapis (L.) has been the subject of several successful introductions in recent years, often in areas with no previous history of the species (Warren, 1981). The continental vanessid Araschnia levana was introduced into Britain in about 1912, and the colonies increased in numbers for several years, until apparently exterminated by a collector (Ford, 1945). Introductions of the Glanville fritillary Melitaea cinxia (L.) have also been claimed (Watson, 1979), and there are doubtless other British examples not on record. In the USA, transfer of eggs and larvae of Euphydryas gillettii Barnes from Wyoming have resulted in the establishment of at least one Colorado population (Holdren & Ehrlich, 1981). Reintroductions have been proposed for Parnassius apollo frankenbergei Slaby (Palik, 1980), and are being implemented for Lysandra bellargus (L.) and the endangered Californian riodinine Apodemia mormo langei Comstock (Arnold et al., 1980). Traditionally, the costs of reintroduction have been very high. This is in part due to the cost of preparing and maintaining sites, but the cost of providing stock is not inconsiderable. However, with the newer methods of rearing butterflies on artificial diets (Singh, 1977; Morton, 1981),
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captive breeding may be highly cost-effective. There is little reason to suppose that funds for conservation will be high on the list of priorities during the present economic crisis. This situation considerably reduces the potential for effective habitat conservation. Combined with the possible need for introductions in any case, these circumstances dictate the need to establish breeding stocks of threatened species as soon as possible. There will then be an alternative to extinction simply because funds were not available to protect or manage habitats. With this in mind, the first Captive Breeding Institute was provisionally formed as an extension of the Lepidoptera Research Foundation (Morton et al., 1980) in the USA.
OBJECTIVES OF THE INSTITUTE It is more efficient to rear a large number of species on one site, using suitably trained and experienced staff, than to leave production of single species to workers in different laboratories. Moreover, this approach does not oblige the field ecologist working with endangered species to invest time and resources in routine laboratory tasks. It is therefore suggested that the majority of livestock production programmes be entrusted to the Institute, which will then 'spread the risk' of accidental losses over a number of production facilities. The Institute will concentrate on the maintenance of butterfly populations, with emphasis on low cost and quality control. In the main, species will be reared on artificial diets by methods already established (Arnold et al., 1980; Morton, 1981). These could allow as many as 20 species, each with population of several thousands, to be maintained by a staff of three--one specialist and two technicians. There will also be a need for some plant production to provide material for ovipositing females. A small garden plot and heated greenhouse would provide material for a wide range of temperate and tropical species. There will be a need for continued research into rearing on diets, and also other aspects which enhance the production of insects, such as stimuli for pairing and ovipositing, pathology and microbiology. It is also anticipated that potential genetic problems will be monitored by behavioural studies and gel electrophoresis. The same facilities are required for mass-production of insects of
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commercial importance. It is therefore anticipated that such commercial activities will help to fund the work with endangered species, and may eventually also support ecological studies on wild populations. Work will also have to be conducted with common species of no commercial interest. These will be used as surrogates to enable development of rearing techniques for closely related endangered species, so that such insects are not put at risk by rearing experiments. There is no reason why rare species for which artificial diets are not yet available could not also be maintained by the Institute, using more traditional techniques. This would, however, prove much more costly and only small numbers could be maintained.
PROPOSED F U N D I N G OF THE INSTITUTE The aim of conservation is to preserve organisms in their natural habitats. It should be emphasised that the Captive Breeding Institute is not an alternative to habitat conservation, but a necessary partner to it. It is therefore important that funding should not be secured at the cost of reduced financing of essential field studies. Although some initial funding is expected to be from conservation bodies and private donations, it is felt that the Institute will function most effectively if it is largely self-financing. This might be achieved in several ways. First, it is proposed to undertake mass-production of species of economic importance. Aspects of biological control are well developed in the USA and the provisional Institute is at present funded by proceeds from mass-production of pink bollworm adults Pectinophora gossypiella Saunders for sterile-release and Heliothis virescens Fab. for pheromone studies, via support from Agresearch Inc., of Los Angeles and Phoenix. Similar markets are poorly developed in Europe at present, but the possibility of large-scale silk production is being examined. Funds may also be available from small-scale production. A number of species which may be reared on diets are ideal for educational work in schools and universities. Others are required for specific research interests, such as Helieonius spp. Interest has also been expressed by some butterfly farms which exhibit live specimens of tropical species, and these could be a major source of funds. It should be emphasised that there is no intention of supplying livestock to collectors or deadstock to anyone.
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Even if such activities were permitted by law, no rare species will form part of the commercial operations of the Institute. The final main source of funding does concern the rare species, where it is hoped that the activities of the Institute will be supported by rearing contracts from specific conservation bodies. However, if funds are available from any other sources such rearing will be undertaken without charge. Indeed, any 'profits' made by the Institutes will be wholly used to maintain further populations, to support research, and to assist with the costs of managing or securing habitats. Further details of the proposals for funding and organisation are available from the author or the Lepidoptera Research Foundation.
CONCLUSIONS There can be little doubt that if funds for conservation are not increased an alarming number of butterflies may become extinct due to loss of suitable habitat. Further, even if sufficient funds are available there may be chance losses of local populations. There is a need to re-examine our attitudes to reintroductions, and possibly populations will benefit if we adopt the approaches of vertebrate conservationists. The most costeffective way to do this will be to fund the establishment of a Captive Breeding Institute in order to ensure survival in captivity and supplies of stocks for reintroduction.
A C K N O W L E D G E M ENTS Thanks are due to Dr R. H. T. Mattoni and Agresearch Inc. for funding my visits to the USA, and providing research facilities for the development of artificial diets for butterflies. Our enthusiastic discussions were greatly encouraged by Dr R. A. Arnold, who assisted at the birth of the Institute. Agresearch Inc. and the Office of Endangered Species/United States Fish and Wildlife Service provided funds for the Institute's work with Apodemia mormo langei. Whilst retaining responsibility for views and opinions expressed in this paper, it is a great pleasure to thank the following for their enthusiastic comments on an earlier discussion document: Professors T o m Eisner and Eric Lees, Drs Jack Dempster,
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John Heath, Michael Morris, Ernie Pollard, Claude Rivers, Jeremy Thomas, Martin Warren and Richard White.
REFERENCES Andrewartha, H. G. & Birch, L. C. (1954). The distribution and abundance of animals. Chicago, Chicago University Press. Arnold, R. A. (1980). Ecological studies of six endangered butterflies (Lepidoptera: Lycaenidae); island biogeography, patch dynamics, and the design of habitat preserves. PhD thesis, University of California, Berkeley. Arnold, R. A., Morton, A. C. & Mattoni, R. H. T. (1980). A captive breeding program for Apodemia mormo langei Comstock (Lepidoptera." Lycaenidae, Riodininae). Proposal prepared for OES/USFWS Los Angeles, Agresearch Inc. Benham, B. R. (1973). The decline (and fall?) of the large blue butterfly. Bull. amat. Ent. Soc., 32, 88-94. Berry, R. J. (1971). Conservation aspects of the genetical constitution of populations. In The scientific management of animal and plant communities for conservation, ed. by E. Duffey and A.S. Watt, 177-206. Oxford, Blackwell. Berry, R. J. & Murphy, H. M. (1970). Biochemical genetics of an island population of the house mouse. Proc. R. Soc. B, 176, 87-103. Bonnell, M. L. & Selander, R. K. (1974). Elephant seals: Genetic variation and near extinction. Science, N.Y., 184, 908-9. Brussard, P. F. & Ehrlich, P. R. (1970). The population structure of Erebia epipsodea (Lepidoptera: Satyrinae). Ecology, 51, 119-29. Chapman, J. A. & Morgan, R. P. (1973). Systematic status of the cottontail complex in western Maryland and nearby West Virginia. Wildl. Monogr., 36. Clarke, C. H. D. (1954). The bob-white quail in Ontario. Tech. Bull. Fish & Wildl. Ser., No. 2. Collier, A. E. (1959). A forgotten discord: the problem of redundancy. Ent. Rec., 71, 118-9. Collier, A. E. (1960). Butterflies in partial eclipse. Ent. Rec., 72, 253-4. Collier, A. E. (1962). Butterflies in the Cranleigh district, 1961. Ent. Rec., 74, 45-7. Curry-Lindhal, K. (1972). Let them live. New York, Murrow. Dempster, J. P. (1971). The population ecology of the cinnabar moth, Tyria jacobaea L. (Lepidoptera, Arctiidae). Oecologia, 7, 26-7. Dempster, J. P. & Hall, M. L. (1980). An attempt at re-establishing the swallowtail butterfly at Wicken Fen. Ecol. Ent., 5, 327-34. den Boer, P. J. (1968). Spreading of risk and stabilization of animal numbers. Acta biotheor., 18, 165-94.
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den Boer, P. J. (1970). On the significance of dispersal power for populations of carabid-beetles (Coleoptera, Carabidae). Oecologia, 4, 1-28. den Boer, P. J. (1971). Stabilization of animal numbers and the heterogeneity of the environment: The problem of the persistence of sparse populations. In Dynamics of populations, ed. by P. J. den Boer and G. R. Gradwell, 77-97. Wageningen, Centre for Agricultural Publishing and Documentation. den Boer, P. J. (1981). On the survival of populations in a heterogenous and variable environment. Oecologia, 50, 39-53. Duffey, E. (I 968). Ecological studies on the large copper butterfly Lycaena dispar Haw. batavus Obth. at Woodwalton Fen National Nature Reserve, Huntingdonshire. J. appl. Ecol., 5, 69-96. East, B. (1974). The endangered species bandwagon. Outdoor Life, 154(5), 51-3, 108-13. Ehrlich, P. R. (1965). The population biology of the butterfly Euphydryas editha, II. The Jasper Ridge colony. Evolution, 19, 327-36. Ehrlich, P. R., Murphy, D. D., Singer, M. C., Sherwood, C. B., White, R. R. & Brown, I.L. (1980). Extinction, reduction, stability and increase: the responses of checkerspot butterfly (Euphydryas) populations to the California drought. Oecologia, 46, 101-5. Ehrlich, P. R., White, R. R., Singer, M. C., McKechnie, S. W. & Gilbert, L. E. (1975). Checkerspot butterflies: A historical perspective. Science, N.Y., 188, 221-8. Fisher, J., Simon, N. & Vincent, J. (1969). Wildlife in danger. New York, Viking. Ford, E. B. (1945). Butterflies. London, Collins. Ford, R. L. E. (1976). The influence of the microgasterini on the populations of British Rhopalocera (Hymenoptera: Braconidae). Ent. Gaz., 27, 205-10. Gardiner, B. O. C. (1974). On vanishing butterflies. Bull. amat. Ent. Soc., 33, 145-51. Hahn, E. (1980). Eleventh hour. The New Yorker, September 1st, 1980, 37-69. Hayes, J. L. (1981). The population ecology of a natural population of the Pierid butterfly Colias alexandra. Oecologia, 49, 188-200. Holdren, C. E. & Ehrlich, P. R. (1981). Long range dispersal in checkerspot butterflies: Transplant experiments with Euphydryas gillettii. Oecologia, 50, 125-9. Hooper, M. D. (1971). The size and surroundings of nature reserves. In The scientific management of animal and plant communities for conservation, ed. by E. Duffey and A. S. Watt, 555-61. Oxford, Blackwell. Klomp, H., van Montfort, M. A. J. & Tammes, P. M. L., (1964). Sexual reproduction and underpopulation. Arch. n~erl, zool., 16, 105-10. Luckens, C. J. (1980). The heath fritillary, Mellicta athalia Rott. in Britain: Notes on distribution and ecology. Ent. Rec. J. Var., 92, 229-34. McLeod, L. (1979). A ban on collecting Lepidoptera in the Department of the Alpes de Haute-Provence, France. Ent. Rec. J. Var., 91, 37-41. Milne, A. (1957). Theories on natural control of insect populations. Cold Spring Harb. Symp. quant. Biol., 25, 253-71.
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