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The bumble and cuckooo bees (Hymenoptera: Apidae: Bombini; Bombus spp. and Psithyrus spp., respectively) are important plant pollinators and any decline in numbers or species constitutes a significant threat both to biological diversity and to whole economies. The distribution, status and factors threatening all 60 known taxa (species and subspecies) of Bombini of 11 countries of Western and Central Europe (Belgium, the Netherlands, Luxembourg, Denmark, Germany, Switzerland, Austria, Czech Republic, Slovakia, Hungary, Poland) were assessed from the beginning of the 20th century. The analysis was based on a literature review, unpublished data, personal communications, our own observations, and an expert review. The IUCN Red List categories were used for assessing the threat of extinction. Eighty per cent of taxa were threatened in at least one country of the region, and 30% of taxa were threatened throughout their range in the countries considered. More species went extinct per country in the second than in the first half of the 20th century, and four taxa went extinct in all 11 countries during 1951–2000. Amongst the factors adversely affecting the Bombini anthropogenic factors (particularly those associated with large-scale farming schemes) appear to be of greater importance than natural factors. To halt population declines and species extinctions it will be necessary to preserve aspects of traditional farming practices and for all Bombini to be afforded legal protection in all countries of the region. The implementation of the European Union's Common Agricultural Policy is likely to have the greatest single impact upon pollinators in the near future.
Following the well documented extinctions of many species of endemic tree snail (family Partulidae) throughout French Polynesia, field surveys were undertaken on four islands in the Society archipelago to provide up to date information for the international conservation programme for this group of invertebrates. These surveys have confirmed the loss of all species of Partula in the wild on the Society Islands other than Tahiti. Thirty-three species have been lost from Raiatea, thereby eliminating one of the most outstanding examples of island evolutionary radiation. On Huahine the disappearance of P. varia and P. rosea, used for making lei (shell jewellery), had an economic and social effect on the local community: many of the women of the villages lost their livelihoods, and the artisan's association folded. The seven species of Partula on Moorea were extinct in the wild by the mid 1980s, terminating almost 100 years of biological research. It now seems that the remnant populations of Samoana attenuata discovered only 5 years ago are the only species of partulid still surviving beyond Tahiti on the Society Island group. The mixed species populations in the Te Pari area of Tahiti-Iti are still extant, but the predatory snail Euglandina rosea has now spread to the last valley on the Peninsula that did not have previous evidence of predator activity. On Tahiti-Nui populations of partulid, without the predator, were found near the crest of Mount Tahiti above Orofero Valley. Partulidae are clearly a highly threatened family of invertebrates, and in need of the most intense conservation focus.
Non-lethal mitigation of crop use by elephants Loxodonta africana is an increasingly important part of protected area management across Africa and Asia. Recently, beehive fences have been suggested as a potential mitigation strategy. We tested the effectiveness of this method in a farming community adjacent to Udzungwa Mountains National Park in southern Tanzania. Over a 5.5-year period (2010–2016) a beehive fence was introduced and subsequently extended along the Park boundary. The probability that one or more farms experienced crop loss from elephants on a given day was reduced in the presence of the fence and was reduced further as the fence was extended. The number of hives occupied by bees along the fence was the best predictor of elephants’ visits to farms. Farms closest to the fence experienced a greater likelihood of damage, particularly during the initial period when the fence was shorter. The number of farms affected by elephants declined when the fence was extended. There was a higher probability of damage on farms that were closer to the Park boundary and further from a road. Our mixed results suggest that the shape, length and location of fences need to be carefully planned because changes in a farm's long-term susceptibility to elephant damage vary between individual farms; fences need to be long enough to be effective and ensure that decreasing crop loss frequency is not outweighed by an increasing number of farms damaged per visit.
The co-extinction of parasitic taxa and their host species is considered a common phenomenon in the current global extinction crisis. However, information about the conservation status of parasitic taxa is scarce. We present a global list of co-extinct and critically co-endangered parasitic lice (Phthiraptera), based on published data on their host-specificity and their hosts’ conservation status according to the IUCN Red List. We list six co-extinct and 40 (possibly 41) critically co-endangered species. Additionally, we recognize 2–4 species that went extinct as a result of conservation efforts to save their hosts. Conservationists should consider preserving host-specific lice as part of their efforts to save species.
The deliberate introduction of the rosy wolf snail Euglandina rosea to the Society Islands in the 1970s led to the mass extirpation of its rich Partulidae (Pilsbry, 1900) fauna, comprising approximately half of all species in this Pacific island tree snail family. On Tahiti ongoing field surveys have documented the survival of two of seven endemic species of Partula (P. hyalina and/or P. clara) in 38 valleys. E. rosea is now a potent extinction agent across Oceania and determining the factors enabling these two taxa to endure may have wide conservation import. We hypothesized that P. hyalina and P. clara have survived because they were the most abundant and/or widespread species and that they will eventually become extinct. We lack demographic data contemporaneous with predator introduction, but an early 20th century study by H.E. Crampton provides historical demographic data for intact Tahitian partulid populations. Crampton found that P. clara and P. hyalina, although widespread, were consistently rarer than their now-extirpated congeners, including in the 23 valleys he surveyed that retain surviving populations. Given this result, and the recent finding that P. clara and P. hyalina comprise a discrete founding lineage in Tahiti, it is plausible that some shared biological attribute(s) may have contributed to their survival. Crampton recorded the clutch sizes of thousands of gravid Tahitian partulids and found that these two taxa had higher instantaneous mean clutch sizes than did co-occurring congeners. Higher fecundities may have contributed to the survival of P. hyalina and P. clara in the valleys of Tahiti.
Terrestrial and freshwater molluscs are amongst the most threatened of all taxa, yet data exist on the distribution and status of only a small proportion of the species. Here we present the results of the first systematic survey of a terrestrial mollusc on the island of Príncipe in the Gulf of Guinea. Archachatina bicarinata has never been previously surveyed, despite being categorized as Vulnerable on the IUCN Red List and suffering from unregulated harvesting for food. We found that A. bicarinata is restricted to primary rainforest and its abundance and probability of occurrence increased as surveyed sites became less accessible. Additional anecdotal evidence from the observations of previous scientific expeditions, local guides and snail harvesters suggested that the species has suffered a dramatic decline in population size and distribution in recent years. We therefore recommend that immediate action be taken to prevent its imminent extinction on Príncipe. The collection of A. bicarinata from protected areas should be banned, as should commercial harvesting and sales. Subsistence collecting should be limited to larger individuals. Our data have been used to inform the management plans for the protected areas on Príncipe and São Tomé, and this should help to ensure the future of A. bicarinata on both islands.
The current distribution of endemic partulid snails on Tahiti in French Polynesia reflects the danger of ignoring expert advice and introducing an alien species into a fragile island ecosystem. The endemic tree-snail fauna of the island now faces extinction. Although the extinction of the native species of Partula (Partulidae; Polynesian tree snails) on Moorea in French Polynesia is well known in the world of conservation biology, losses on other Pacific islands are less well described. This paper presents an update on the status of partulid snail populations on Tahiti in the light of fieldwork undertaken between 1995 and 1997. Native snails still exist in good numbers in two areas, at opposite ends of the island. In other areas, sightings of single or a few individuals indicate remnant populations now on the edge of extinction. Efforts to protect these populations and others in French Polynesia are being planned in collaboration with local government authorities.
Invertebrates living in underground environments often have unusual and sometimes unique adaptations and occupy narrow ranges, but there is a lack of knowledge about most micro-endemic cave-dwelling invertebrate species. An illustrative case is that of the flatworm Dendrocoelum italicum, the first survey of which was performed 79 years after its description. The survey revealed that the underground stream supplying water to the pool from which the species was first described had been diverted into a pipe for human use, thus severely reducing the available habitat for the species. Here we describe the results of what we believe is the first habitat restoration action performed in a cave habitat for the conservation of a flatworm. The water-diverting structure was removed, with the involvement of local protected area administrators, citizens and volunteers from local organizations. The intervention resulted in the restoration of a large, stable pool inside the cave, thus creating an optimal habitat for this threatened planarian, with increased availability of prey and a stable population. This report of habitat restoration for a neglected invertebrate offers insights for the protection of other micro-endemic species.
Population decline among Asian horseshoe crabs in Asia is increasingly reported, but knowledge of their population and ecological status in China is limited. We conducted community interviews in 30 fishing villages around Beibu Gulf in Guangxi, China, to collect distribution information about the potential spawning/nursery grounds of Tachypleus tridentatus and Carcinoscorpius rotundicauda, and any imminent threats to their populations. Based on the results from 400 respondents we identified 45 potential spawning/nursery grounds distributed widely along the shores of Beibu Gulf. We visited 10 of these sites and verified the presence of juvenile horseshoe crabs by field surveys. Nearly all respondents reported an overall depletion in horseshoe crab populations from these 45 sites, which they attributed mainly to unsustainable fishing practices. Respondents who reported having seen horseshoe crab mating pairs on shores were mostly older people, which may suggest a considerable reduction in horseshoe crabs coming to the shores to spawn in recent years. The mean daily harvest of adult T. tridentatus offshore, as indicated by fishers, has declined from c. 50–1,000 in the 1990s to 0–30 individuals during 2011–2016. Our Wisdom of Crowds approach, supported by confirmatory field surveys, is a cost-effective method for assessing the population status of horseshoe crabs, and the level of threat they face. Similar approaches with other species are likely to be particularly valuable in the Asia–Pacific region, where well-structured population monitoring is largely unaffordable.
South-east Asian apple snails, Pila spp., have been declining since the introduction of globally invasive, confamilial South American Pomacea spp., yet Pila ecology remains poorly studied, with most occurrence records unconfirmed. Pila scutata, a previously widespread species, presumed native to the Malay peninsula and assessed as Least Concern in the IUCN Red List, was formerly harvested for food, and may have experienced anthropogenic translocations. We surveyed the Malay peninsula (specifically Peninsular Malaysia and Singapore) to investigate the current distribution and genetic diversity of P. scutata. Six populations were found in Singapore, but only one in Peninsular Malaysia. Mitochondrial COI and 16S sequencing revealed that the Malaysian population shared a single haplotype of both genes with the Singapore populations (500 km distant). This low genetic diversity could stem from a recent anthropogenic introduction, which brings into question the true native range of P. scutata and, coupled with poorly resolved taxonomy of the genus, necessitates a reassessment of its IUCN Red List status. Introduced populations pose a dilemma, and the lack of genetic diversity is of concern in light of Pila decline throughout South-east Asia. Our results highlight that conservation management of P. scutata and its congeners must therefore be better informed by greater taxonomic resolution and more comprehensive investigations of their ecology, both in native and introduced ranges.
The endemic snails of the Galápagos are threatened—by introduced fire ants, by black rats and by the destruction of the Scalesia forest that is home to many of them. More than 30 endemic bulimulid snails are now considered endangered there, many of them occurring only in the 10 per cent of the Galápagos that does not have national park status. The problems of protecting them are formidable, and failure would mean the loss not only of individual species, but of a rare opportunity to study speciation in a natural laboratory.
Livestock grazing is a key factor in many grassland ecosystems and can substantially influence the conservation of grassland species. The Crau steppe in southern France is a protected area that is traditionally grazed by sheep. The Critically Endangered Crau plain grasshopper Prionotropis rhodanica is endemic to the area and a flagship for the conservation of this unique ecosystem. Its population has declined significantly during the last 2 decades, but the reasons remain poorly understood. One potential factor is an altered habitat structure caused by changes in the grazing regime. We examined the microhabitat preferences of the species and compared the habitat structure of populated sites with those where the species is now extinct (former habitat). We found that populated sites had denser and higher vegetation, whereas former habitat had higher cover of stones and bare ground. Vegetation structure in the habitat of the smallest subpopulation was similar to areas of former habitat, suggesting a marginal habitat quality. Our results show that P. rhodanica requires 50–70% vegetation cover and suggest that grazing has contributed considerably to the population decline, but it remains unclear whether this is a direct effect of habitat degradation or an indirect effect by attracting predators associated with grazing activities. We recommend careful management of grazing to improve habitat quality, which would also benefit other invertebrates and insectivores. Continued monitoring is required to conserve habitat specialists in protected areas.
Monitoring rare and elusive species for effective management and conservation is particularly challenging and often demands the development of specialized techniques. Scat surveys have been applied to monitor a variety of rare species but relatively little attention has been given to the development of appropriate sampling designs. To determine if scat surveys could be applied to compare the distribution of species across three habitats of a fragmented region in the Brazilian Amazon, the removal of human (n = 27) and jaguar (n = 27) scat samples in forest, riparian corridor and pasture habitats was recorded for 24 hours. Dung beetles were responsible for removing the majority of samples (71%) and a generalized linear mixed effect model revealed significant influence of habitat and scat type on removal probability, with forest and riparian corridors having higher removal compared with samples in pasture habitats. Although non-invasive scat surveys can potentially address fundamental broad-scale conservation and management questions, our results demonstrate that scat surveys in the tropics must account for differences in scat removal rates between habitats and target species before conclusions can be drawn regarding patterns of habitat use.
The majority of the biomass and biodiversity of life on the Earth is accounted for by microbes. They play pivotal roles in biogeochemical cycles and harbour novel metabolites that have industrial uses. For these reasons the conservation of microbial ecosystems, communities and even specific taxa should be a high priority. We review the reasons for including microorganisms in conservation agenda. We discuss some of the complications in this endeavour, including the unresolved argument about whether microorganisms have intrinsic value, which influences some of the non-instrumental motivations for their conservation and, from a more pragmatic perspective, exactly what it is that we seek to conserve (microorganisms, their habitats or their gene pools). Despite complications, priorities can be defined for microbial conservation and we provide practical examples of such priorities.
The spectacular partulid tree snail fauna of the Society Islands has been almost completely extirpated in recent decades following the deliberate introduction of the alien carnivorous snail Euglandina rosea. The greatest loss has occurred on the island of Raiatea, French Polynesia, home to an estimated 34 species (including 33 single-island endemics), all of which have been deemed extirpated in the wild. However, we report here the February 2006 discovery of two surviving Raiatean partulid lineages on the upper slopes of Mount Tefatua, the highest peak on the island. They have been identified using morphological and molecular phylogenetic analyses, the latter approach employing available museum and captive reference samples. One population, at 750 m elevation, consisted of Samoana attenuata. It has a multi-island distribution within the archipelago and surviving populations persist also on Tahiti and Moorea. A second population, present just below the summit at 950 m, consisted of a previously unstudied morphospecies and it has been formally described as Partula meyeri. It is unclear if a stable altitudinal refuge from E. rosea predation exists on Mount Tefatua but the unexpected discovery of these two surviving montane populations raises the possibility of preserving some fraction of Raiatea's endemic tree snail diversity in the wild.
The shell of the Manus green tree snail Papustyla pulcherrima is renowned for its beauty and is subject to international protection under CITES, having been harvested intensively in the past. To determine its threat status, and whether further conservation action is justified, an inexpensive Wisdom of Crowds approach was used to estimate the change in relative density of the snail between 1998 and 2013. Local men and women were approached around the main market on Manus Island, Papua New Guinea, and asked to map the relative abundance of the snail on an ordinal scale, based on their personal observations in 2013 and 1998 (a year of cultural significance). The spatial abundance data from 400 surveys were analysed using an information-theoretic approach. A suite of cumulative link models incorporating geographical factors was used to determine the magnitude of the change and to investigate possible biological influences underpinning the reported pattern. High abundance of the snail was associated with intact forested areas, high elevation and low population density. A slow decline was evident, with the median percentage of map cells where the snail was categorized as plentiful decreasing by c. 20% between the 2 years. On this basis a categorization of Near Threatened was advocated for the species. Although it is arguable that Wisdom of Crowds methods cannot be substituted for in situ quantification, the approach appears to have utility as a preliminary assessment for further conservation expenditure, and as a tool for determining threat status.