The following case studies have been selected to help illustrate the cur- rent range, efficacy and wider value of insect conservation breeding programmes.
5.1 The field cricket, Gryllus campestris
5.1.1 Programme background
Due to alteration and fragmentation of its highly selective grassland habitat, by the late 1980s, the UK population of the field cricket, Gryllus campestris, was reduced to a single colony of fewer than 100 individuals in West Sussex (Edwards et al., 1996). In 1991 the species was placed on English Nature’s Species Recovery Programme (SRP). The SRP action plan called for the estab- lishment of ten secure field populations in areas of the species’ historic range (M. Edwards, 1995, unpublished data). Because the surviving population was too low to support direct translocations, the development of a conserva- tion breeding programme was required, and in 1992 a breeding and rearing initiative was established at the Zoological Society of London. The strategy entailed collecting three pairs of subadult crickets from the surviving wild population each spring. These were to be bred at the London zoo to produce large numbers of late-instar F1 generation nymphs for the establishment of new colonies in sites identified by the SRP ecological team.
5.1.2 Management summary
The management regime is detailed in Pearce-Kelly et al. (1998) and Jones et al.
(1999). To help clarify natural health profiles, a faecal screening and post- mortem protocol was implemented for all field-collected founder crickets. Newly col- lected crickets were reared to the adult stage and paired up in standard aquar- ium tanks partly filled with a sandy soil mix topped with a sod of turf from
the wild colony site. Hatching nymphs were transferred to nursery tanks fur- nished with egg cartons to optimize moulting conditions. Timer-controlled radiant basking bulbs helped synchronize nymphal development rates with those of the wild population. The crickets were housed in an isolated breed- ing room to reduce the risk of disease contamination from non-native insect species. Separate progeny lines were maintained to ensure maximum genetic diversity in the ex situ F1 population prior to combining for field release.
5.1.3 Results
Overall breeding and rearing success has been high, with annual mortality rates ranging between 10% and 20% in the Fl nymphs. To date, the breed- ing programme has provided in excess of 17,000 late-instar nymphs for the SRP field establishment programme. The importance of effective post-arrival and pre-release health-screening protocols was highlighted by the discovery in 1996 and 1997 of gregarine parasites in the captive population, prevent- ing field releases in both those years (A. Cunningham et al., 1996, unpub- lished data; Pearce-Kelly, 1997). This underlines the necessity of ensuring that ad equate infection barriers are in place for all ex situ populations destined for reintroduction. Four of the seven field colonies established with zoo-bred crickets are still extant, the longest of which was shown to have persisted to the eighth generation without the need for reinforcement. In addition to pro- viding large numbers of release stock, the breeding programme helped clarify fecundity ranges (D. Clarke, 2005, unpublished data). The knowledge derived from monitoring the fluctuation dynamics of the field-released G. campestris populations has informed optimal site management requirements for the spe- cies, and helped clarify the subtle environmental factors influencing colony survival. The breeding programme has also helped raise public awareness of the field cricket and its conservation issues and provides a model for develop- ing similar recovery initiatives for the species in other range countries.
5.2 The wart-biter bush cricket, Decticus verrucivorus
5.2.1 Programme background
Although a relatively common species in areas of its mainland European range, the British population of Decticus verrucivorus is confined to a handful of isolated sites in the South of England, providing the necessary sheltered, lightly-grazed, chalk grassland habitat it requires (Cherrill, 1993; Cherrill and Brown, 1993). The cricket is omnivorous, feeding on a variety of plant and insect species. The embryo normally goes through two diapauses and the first may last several years (Ingrish, 1994). The cricket was placed on English Nature’s SRP in 1991. The associated action plan required the establishment of additional colonies in areas of the species’ historic range (Shaughnessy and Cheesman, 2005). To provide the large numbers of late-instar nymphs neces- sary for establishing new field populations, a breeding programme was estab- lished at the London Zoo using 500 eggs obtained from wild-caught females originally collected for a dietary research project at Imperial College.
5.2.2 Management summary
The management regime is described in Pearce-Kelly et al. (1998) and Jones et al. (1999). An environmental chamber was used to take the eggs through their summer and winter development cycle. To reduce the incidence of can- nibalism and optimize moulting conditions, hatching nymphs were housed in low density groups of around 10 individuals. Timer-controlled radiant basking bulbs were used to synchronize nymphal development with the wild popula- tion. Adults were housed as breeding pairs in standard aquarium plastic tanks with a sandy soil substrate for oviposition. A predominately natural plant food diet was provided, supplemented with wax moth larvae. A pre-release health- screening protocol was implemented from the outset of the programme.
5.2.3 Results
The first year’s breeding season produced in excess of 3000 eggs. Unlike the field cricket, the wart-biter’s more demanding husbandry and diet require- ments meant that relativity low numbers could be reared for field release (Jones et al., 1999). The discovery, and successful eradication, of a fungal infection in the ex situ population (Cunningham et al., 1997; Pearce-Kelly, 1997) highlights the importance of effective health monitoring. In excess of 500 late-instar crickets were provided to the SRP for several sets of field- releases into two sites, one of which also had translocations. Follow-up monitoring of these new populations has confirmed sustained colony per- sistence (Shaughnessy and Cheesman, 2005). The wart-biter cricket breeding programme provided additional information on the developmental biology of the species, in particular, the maximum egg developmental period was shown to be at least 2 years greater than the 7 years recorded by Ingrish (1994). Significant levels of media and public interest helped highlight the plight of the species and the importance of the wider SRP initiative.
5.3 Middle Island tusked weta, Motuweta isolata
5.3.1 Programme background
The New Zealand weta family Anostostomatidae, formerly Stenopelmatidae (Johns, 1998) demonstrates a high degree of endemicity to New Zealand (Gibbs, 1998). Many species are vulnerable to habitat loss or alteration and are extremely sensitive to introduced predatory fauna, especially mammals (Gibbs, 1998; McIntyre, 2001). One species in dire need of conservation man- agement is the Middle Island tusked weta, Motuweta isolata (Johns, 1998).
This species has only been found in certain areas of the 13 ha Middle Island situated off the Coromandel Peninsula on the east coast of the North Island.
The Department of Conservation’s (DoC) M. isolata recovery plan identified the need to establish the species on other offshore islands via a breeding and release programme (Sherley, 1998). Project Weta was initiated in 1986 and by 1991 had worked with a total of seven species (Barrett, 1991). Since this time, a further ten species had been worked on up until 2006 with a total of 12 species being bred to the first generation and some through to the fourth
generation. This experience provided the confidence to develop a breeding and release programme for M. isolata between 1999 and 2001 in collaboration with Chris Winks of Land Care Research and Ian Stringer, then of Massey University. Three captive populations were subsequently established.
5.3.2 Management summary
The initial breeding group at Land Care Research, Mt Albert Auckland pro- vided 60 first-instar nymphs to Auckland Zoological Park between August and November of 1999. These were raised through years 2000–2001. Two groups of nymphs were translocated to Double Island, in the Mercury Island group during the year 2000. The remainder were retained at the zoo and raised separately before being paired and subsequently translocated to Double Island between May and September 2001. The weta were kept in an air-conditioned room at a temperature of 17–20°C, with humidity levels at 60–90%. The animals were fed fish flakes, leaves and insects. A 2-l container of soil was provided in the breeding enclosures for oviposition. A succession of males were paired with each female.
5.3.3 Results
With only two mortalities, a total of 58 of the Project Weta stock were reared to suitable stages for field release. Initially 39 nymphs were released, fol- lowed by 19 adults after they had been mated and were laying eggs. These were added to animals from the other breeding programme groups to pro- vide a total of 120 crickets for release on Double and Red Mercury Islands.
They were established under special shelters prepared by Rob Shappell of DoC. Eggs were subsequently collected from all three captive populations and incubated at the Land Care Research facility with eclosion occurring in October 2001. The rearing of this second generation population resulted in a further 106 animals being translocated to the islands. Progeny that had completely developed in situ were confirmed on both islands in March 2003 (eight on Mercury and three on Double Island) and all were adult or large juveniles (I. Stringer, 2003, personal communication).
5.4 The Karner blue butterfly, Lycaeides melissa samuelis
5.4.1 Programme background
The Karner blue butterfly Lycaeides melissa samuelis is a resident of oak savan- nah, pine barren and sand barren habitats of the Midwest, mid-Atlantic and New England regions of the USA. Within these arid habitats resides its sole host plant, wild lupine Lupinus perennis (Dirig, 1994). In the last 25 years, the butterfly has suffered a dramatic population decline throughout its range primarily from habitat loss and fragmentation. Originally native to 12 states and one Canadian province, the species is now extant in Indiana, Michigan, Minnesota, New Hampshire, New York and Wisconsin. It was placed on the US Endangered Species Act in 1992. The species was reintroduced to Ohio in 1998 to a region of restored oak savannah and sand barren habitats near the
western shore of Lake Erie. A recovery team was formed to spearhead the rein- troduction effort. The team devised a seven-part strategy for recovery: (i) host plant propagation; (ii) reintroduction site selection, evaluation and manage- ment; (iii) post-management evaluation; (iv) breeding protocol development;
(v) founder selection; (vi) captive breeding; and (vii) release and monitoring.
The Nature Conservancy would manage habitat restoration and of the chosen release site. Staff from the Toledo Zoo would assess the habitat to determine its suitability for reintroduction. Zoo staff were also charged with host plant propa gation, captive breeding and monitoring. The recovery plan specified that first generation adult female founders would be captured and placed on potted plants for egg deposition. Larvae would be reared on the plants through the life cycle to eclosion. Second generation adults would be transported to the introduction site and released. The species is bivoltine, producing two gener- ations per season, the first May to June, the second July to August. The species over-winters in the egg stage, hatching the following April.
5.4.2 Management summary
Annually from 1998 to 2002, Toledo Zoo staff captured first generation adult females from sites in Michigan. Individual females were placed in a clear plas- tic container that was then positioned in a cooler for transport to the zoo. Each female was sequestered on a potted host plant covered with a cylindrical net.
Adults were hand-fed daily using a honey-water solution. Eggs were typically deposited on the leaves and petioles of the host after one or two days. Once hatched, larvae were closely monitored. To negate cannibalism, second-instar larvae were moved to new plants so that no more than ten were on a single plant.
Host plants were replaced regularly. Small pieces of pine bark were added to the soil surface of the potted plant during the final instar. Larvae would then crawl under the bark to pupate. Adults were transported to the release site in the afternoon following eclosion. The rearing unit was enclosed in a double barrier and isolated from other invertebrates in the collection. Instruments, as well as the floor, benches and other equipment were regularly disinfected.
5.4.3 Results
From 1998 to 2002, nearly 1700 adults were released at the Ohio reintroduction site. Since the cessation of captive breeding activities in 2002, the butterfly has expanded its range beyond the initial site and is now found throughout the 200 ha preserve. In addition, there has been a quantified large shift in population density from the original release site to another location 1000 m downwind.
Recent efforts by the recovery team are focusing on the preparation of add- itional release sites and studying oviposition preferences of females in situ.
5.5 The barberry carpet moth, Pareulype berberata
5.5.1 Programme background
Previously widespread in Wales and England, as far north as Yorkshire, the UK population of the barberry carpet moth, Pareulype bererata, suffered a dramatic
decline as a result of hedgerow loss and eradication of its once common food plantBerberis vulgaris. By 1987, the species was restricted to a single known site in Suffolk and was made a Schedule 5 and Biodiversity Action Plan listed species.
The British popu lation was saved from imminent extinction by Paul Waring, who bred sufficient numbers from the remaining population to enable a con- certed conservation initiative to be developed. This effort was initially led by the Joint Nature Conservancy Council, and then in 1991 was adopted by English Nature’s Species Recovery Programme in partnership with a group of UK zoos.
The breeding programme remit called for participating zoos to breed large numbers of late-instar moth larvae, together with their food plant, to be used to establish new populations in restored areas of the species’ former UK range. The species is capable of producing two generations per year with moths emerging between April–June, and July–September, with the second generation of pupae over-wintering to emerge the following spring (Waring, 1990).
5.5.2 Management summary
Five participating zoos, Bristol, Dudley, Paignton, Penscynor and Whipsnade, along with a number of private individuals followed a simple breeding and rearing protocol. This was based on a combination of larvae reared on indi- vidually netted food plants and in a larger rearing units housing around 20 potted food plants. To reduce disease risk, the rearing areas were isolated from non-native invertebrate species. Other biological barrier measures included servicing the moths before other invertebrate species, wearing overalls and dis- posable gloves, and using a disinfectant foot dip. All equipment required for care of the moths remained within the rearing unit and a double door system reduced the risk of inadvertent escape of free flying adults.
5.5.3 Results
Increasingly successful breeding and rearing results were achieved by most participating institutions. Provision of animals for field release reached a peak in the year 2000 when a combined 147 moths emerged in the spring and pro- duced a surplus of 4413 eggs and larvae of which 3793 larvae went to release projects. The season ended with approximately 1000 pupae being over-win- tered at seven institutions in readiness for the 2001 season (Hughes, 2000). In recent years the breeding programme’s emphasis has shifted to help improve understanding of the moth’s autecology, especially egg- laying preferences, over-wintering and summer pupation requirements and adult flight behav- iour. The establishment of new populations within the grounds of participat- ing institutions has emerged as the most practical way of gathering these data.
Accordingly, large-scale plantings of the moth’s larval food plant, B. vulgaris, are currently underway to create suitable establishment habitats.
5.6 The American burying beetle, Nicrophorus americanus
5.6.1 Programme background
American burying beetles (ABBs) are the largest Nicrophorus spp. in the USA, measuring up to 37 mm. For successful reproduction ABBs require a vertebrate
carcass (raging between 100 and 200 g), which is buried and prepared by both male and female for use as a food source for their larvae. The historic range of the ABB was eastern and central USA (35 states) and along the southern borders of Ontario, Quebec and Nova Scotia in Canada. A serious decline in this species was noticed in the late 1800s through the mid-1900s. Now the only naturally occurring population east of the Mississippi river is found on Block Island (BI) off the southern coast of Rhode Island, West of the Mississippi river. ABBs can still be found in eastern Oklahoma, Arkansas, eastern Kansas, central Nebraska, extreme southern South Dakota, and just recently were discovered in Texas.
Reasons for the disappearance over 90% of the ABBs range may include loss of carcass-base in the necessary weight range for reproduction, such as the pas- senger pigeon Ectopistes migratorus and the greater prairie chicken Tympanuchus cupido. Habitat loss, alteration and fragmentation are causing a change in species composition resulting in greater competition for the carrion resources needed for reproduction. Other factors may include pesticides, disease, artificial light- ing and electric bug zappers. The US Fish and Wildlife Service (USFWS) listed the ABB as endangered in 1989 and by 1991 had completed a recovery plan for the species (Raithel, 1991). The recovery plan called for the monitoring, man- aging and protection of existing populations, searches for additional popula- tions and to implement a reintroduction plan using captive reared beetles.
5.6.2 Management summary
A pilot reintroduction and study was launched in 1990 and continued through 1993 on Penikese Island (PI), Massachusetts using beetles captive reared at Boston University (BU) by Andrea Kozol. The success of this pilot study led to a second reintroduction in 1994 on Nantucket Island (NI), Massachusetts.
Roger Williams Park Zoo (RWPZ) was asked to participate in the recovery effort and received 19 male and 11 female beetles from BU that had been collected as larvae on BI. This colony was reared by RWPZ using the hus- bandry and breeding protocol developed at BU (A.J. Kozol, Concord, 1992, unpublished data). Beetles were maintained at 20–23°C with a 12-hour light cycle. Depending on the size of container used, 1–20 same sex sibling beetles were housed together on a moistened paper towel substrate. Newly emerged beetles are ravenous feeders and were fed heavily for the first 2 weeks (8–12 mealworms a day) after which feeding rates reduced to 6–8 mealworms a day. Breeding was carried out in 11-l plastic buckets filled with soil to about 5 cm from the top and covered with plexiglas lids. A pair of beetles was placed on the surface of the soil and given an optimal size rat or quail carcass.
5.6.3 Results
The NI reintroduction programme continued from 1994 to 2005 with RWPZ rearing and supplying USFWS with over 2500 beetles for release on NI. The sta- tus of this population continues to be regularly monitored. This programme has shown how zoos working in partnership with federal and local wildlife agencies can successfully meet the conservation breeding requirements of such species recovery initiatives (Amaral and Prospero, 1999). In addition to providing large numbers of animals for field release, the breeding programme
for this species has allowed for the collection of data on husbandry and repro- ductive behaviours not easily observed in the wild (Wetzel, 1995). This effort has also led to the establishment of educational programmes providing public awareness of the ecosystem roles of insects and the importance of invertebrate conservation (Perrotti et al., 2001).
5.7 The Frégate Island giant tenebrionid beetle, Polposipus herculeanus
5.7.1 Programme background
The Frégate Island giant tenebrionid beetle, Polposipus herculeanus, is a large, flightless beetle endemic to wooded habitat on Frégate Island in the Seychelles.
The species has an IUCN Red List designation of ‘Critically Endangered A2e’
(Baillieet al., 2004) on the basis of its extremely limited distribution and the accidental introduction of the brown rat, Rattus norvegicus, to the island in 1995 (Lucking and Lucking, 1997; Millet, 1999). In 1996, with the support of Frégate Island Private, Government of Seychelles, the Nature Protection Trust of Seychelles and Nature Seychelles, an ex situ population was estab- lished at the Zoological Society of London with 47 wild-caught founders, followed by an additional founder line of 20 animals in May 1999. The con- servation remit was to establish a secure ex situ population and to provide as much life-history, reproductive and disease profile data as possible to inform in situ conservation management efforts.
5.7.2 Management summary
The management regime is comprehensively detailed in Ferguson and Pearce-Kelly (2004). The beetles were housed in large plastic tubs with a min- imum 30 cm depth of soil substrate to allow larvae to burrow and pupate.
A tree branch, secured vertically within each tub, allowed natural arboreal behaviour to be expressed and increased available surface area. Each tub accommodated between 50 and 100 beetles. Ambient night temperature was about 25°C and rose to approximately 28°C during the day, and relative humidity ranged between 65% and 75%. Natural spectrum fluorescent lights provided 12 h of daylight. The beetles’ largely nocturnal behaviour could be studied using red spectrum lighting to which the beetles appear to be insensitive. Their diet consisted of a variety of fruit and vegetables, decay- ing leaf litter and wood. The beetles were normally kept as single generation populations.
5.7.3 Results
The Frégate beetles have proved to be a relatively straightforward species to maintain in culture with modest maintenance needs. The ex situ programme has realized its husbandry development remit with additional breeding groups successfully established in four other European zoos (Bristol, Artis, Riga and Poznan) culminating in a formalized EEP in 2002. A range of life- history, reproductive and health-related studies have helped clarify longevity, life-stage durations and generation length (Ferguson and Pearce-Kelly, 2005).