Niche conservatism and the invasive potential of the wild boar

Changes in wild pig (Sus scrofa) relative abundance, crop damage, and environmental impacts in response to control efforts

BACKGROUND

As the population and range of wild pigs (Sus scrofa) continue to grow across North America, there has been an increase in environmental and economic damages caused by this invasive species, and control efforts to reduce damages have increased concomitantly. Despite the expanding impacts and costs associated with population control of wild pigs, the extent to which wild pig control reduces populations and diminishes environmental and agricultural damages are rarely quantified. The goal of this study is to quantify changes in wild pig relative abundance and subsequent changes in damages caused by invasive wild pigs in response to control.

RESULTS

Using a combination of wild pig population surveys, agricultural damage assessments, and environmental rooting surveys across 19 mixed forest-agricultural properties in South Carolina, USA, we quantified changes in wild pig relative abundance and associated damages over a 3-year period following implementation of a professional control program. Following implementation of control efforts, both the number of wild pig detections and estimated abundance decreased markedly. Within 24 months relative abundance was reduced by an average of ~70%, which resulted in a corresponding decline in environmental rooting damage by ~99%.

CONCLUSION

Our findings suggest that sustained wild pig control efforts can substantially reduce wild pig relative abundance, which in turn resulted in a reduction in environmental rooting damage by wild pigs. Ultimately this study will help fill critical knowledge gaps regarding the efficacy of wild pig control programs and the effort needed to reduce impacts to native ecosystems, livestock, and crops. © 2023 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

One Health at gunpoint: Impact of wild boars as exotic species in Brazil - A review

Wild boars have been listed among the 100 most invasive species worldwide, spreading impacts to all continents, with the exception of Antarctica. In Brazil, a major source of introduction was a commercial livestock importation for exotic meat market, followed by successive escapes and releases to natural ecosystems. Currently found in all six Brazilian biomes, with reports in 11 Brazilian states, wild boars have invaded natural and agricultural areas. Wild boars have been reportedly indicated as hosts and reservoirs of several zoonotic diseases in Brazil, including toxoplasmosis, salmonelosis, leptospirosis, brucellosis, tuberculosis, trichinellosis, and hepatitis E. Wild boars have been also associated with Brazilian spotted fever and rabies, infected while providing plentiful exotic blood supply for native ticks and hematophagous bats. Due to their phylogenetic proximity, wild boars may present ecological niche overlapping and direct disease risk to native white-lipped and collared peccaries. Moreover, wild boars may post an economical threat to Brazilian livestock industry due to restrictive diseases such as Aujeszky, enzootic pneumonia, neosporosis, hemoplasmosis, and classic swine fever. Finally, wild boars have directly impacted in environmentally protected areas, silting up water springs, rooting and wallowing native plants, decreasing native vegetal coverage, disbalancing of soil components, altering soil structure and composition. Wild boar hunting has failed as a control measure to date, according to the Brazilian Ministry of Environment, due to private hunting groups mostly targeting males, intentionally leaving females and piglets alive, disseminating wild boar populations nationwide. Meanwhile, non-government animal welfare organizations have pointed to animal cruelty of hunting dogs and wild boars (and native species) during hunting. Despite unanimous necessity of wild boar control, eradication and prevention, methods have been controversial and should focus on effective governmental measures instead occasional game hunting, which has negatively impacted native wildlife species while wild boars have continuously spread throughout Brazil.

Use of Wild Boar (Sus scrofa) as a Sustainable Alternative in Pork Production

Pork production involves several sustainability issues. The recent increase in the natural wild boar population and the possibilities of its breeding to produce meat and for sport hunting have revived attention on this wild species. The most important factors that could account for its expansion and niche invasion are briefly summarized with the scientific opinion on management strategies. The information available to date on the quantitative, nutritional, and sensory characteristics of wild boar meat is reviewed to highlight its potential, if properly managed, as a sustainable option in meat production. This review reports on the opportunity of using wild boar meat in processed products and the need for research on processing qualities and acceptability for different final products. Above all, this review suggests that wild boar can be considered a sustainable alternative to meet the animal protein demand, as it can be established in marginal areas where it is already adapted to the environment, representing an interesting addition to traditional zootechnics.

Landscape Genetic Analysis for the Japanese Wild Boar in the Early Expanding Stage in the Hokuriku Region of Japan

As a contribution to improving management of the Japanese wild boar (Sus scrofa leucomystax), which has recently expanded its range and is having some negative effects on the ecosystem, we conducted a landscape genetic study using individual-based genetic analysis and multiple landscape elements to elucidate its dispersal patterns in the early stage of its expansion. Microsatellite DNA analysis of Japanese wild boars in the Hokuriku region of Japan revealed the existence of two ancestral genetic clusters, that they had migrated via different pathways, and that they were inadequately admixed. We also inferred the most suitable habitats for Japanese wild boar using MaxEnt and concluded that lower elevation and snowfall may favor the occurrence of wild boar individuals. Landscape genetic analysis indicated regional differences in Japanese wild boar dispersal patterns, according to the spatial heterogeneity of genetic features and landscape elements. On the western side of the study area, where individuals with a high frequency of one of two ancestral clusters were more abundant, significant effects of isolation by distance and resistance due to the above two landscape factors were detected, suggesting unidirectional dispersion influenced by the alpine landscape. In contrast, on the eastern side, there was indication of resistance to dispersal of individuals predominantly possessing another ancestral cluster, suggesting the influence of irregularly arranged suitable habitats due to the complexity of the mountainous terrain. Based on our findings, we conclude that Japanese wild boar dispersal patterns may be influenced by landscape elements, such as alpine mountains.

Constructing an Ensemble Model and Niche Comparison for the Management Planning of Eucalyptus Longhorned Borer Phoracantha semipunctata under Climate Change

Phoracantha semipunctata is a destructive invasive alien forest pest worldwide. It primarily damages the eucalyptus via adults, affecting almost all parts of the eucalyptus. Its larvae develop in almost all major tissues of the plant. Phoracantha semipunctata spreads both via the migration of adults and global trade in intercontinental translocation. Currently, this pest has spread to six continents worldwide, except Antarctica, resulting in substantial economic losses. Based on global occurrence data and environmental variables, the potential global geographical distribution of P. semipunctata was predicted using an ensemble model. The centroid shift, overlap, unfilling, and expansion scheme were selected to assess niche dynamics during the global invasion process. Our results indicated that the AUC and TSS values of the ensemble model were 0.993 and 0.917, respectively, indicating the high prediction accuracy of the model. The distribution pattern of P. semipunctata is primarily attributed to the temperature seasonality (bio4), mean temperature of the warmest quarter (bio10), and human influence index variables. The potential geographical distribution of P. semipunctata is primarily in western and southwestern Asia, western Europe, western and southern North America, southern South America, southern Africa, and eastern and southern Oceania. The potential geographical distribution of P. semipunctata showed a downward trend in the 2030s and the 2050s. The distribution centroid showed a general tendency to shift southward from the near-current to future climate. Phoracantha semipunctata has largely conserved its niche during the global invasion process. More attention should be paid to the early warning, prevention, and control of P. semipunctata in the countries and regions where it has not yet become invasive.

Primates facing climate crisis in a tropical forest hotspot will lose climatic suitable geographical range

Global climate changes affect biodiversity and cause species distribution shifts, contractions, and expansions. Climate change and disease are emerging threats to primates, and approximately one-quarter of primates' ranges have temperatures over historical ones. How will climate changes influence Atlantic Forest primate ranges? We used habitat suitability models and measured potential changes in area and distributions shifts. Climate change expected in 2100 may change the distribution area of Atlantic Forest primates. Fourteen species (74%) are predicted to lose more than 50% of their distribution, and nine species (47%) are predicted to lose more than 75% of their distribution. The balance was negative, indicating a potential future loss, and the strength of the reduction in the distribution is related to the severity of climate change (SSP scenarios). Directional shifts were detected to the south. The projected mean centroid latitudinal shift is ~ 51 km to the south for 2100 SSP5-8.5 scenario. The possibility of dispersal will depend on suitable routes and landscape configuration. Greenhouse gas emissions should be urgently reduced. Our results also emphasize that no more forest loss is acceptable in Atlantic Forest, and restoration, canopy bridges, friendly agroecosystems, and monitoring of infrastructure projects are urgent to enable dealing with climate change.

The Boar War: Five Hot Factors Unleashing Boar Expansion and Related Emergency

The recent and ever-growing problem of boar (Sus scrofa forms including wild boar, hybrid and feral pig) expansion is a very complex issue in wildlife management. The damages caused to biodiversity and the economies are addressed in different ways by the various countries, but research is needed to shed light on the causal factors of this emergency before defining a useful collaborative management policy. In this review, we screened more than 280 references published between 1975–2022, identifying and dealing with five hot factors (climate change, human induced habitat modifications, predator regulation on the prey, hybridization with domestic forms, and transfaunation) that could account for the boar expansion and its niche invasion. We also discuss some issues arising from this boar emergency, such as epizootic and zoonotic diseases or the depression of biodiversity. Finally, we provide new insights for the research and the development of management policies.

Suitable areas for invasive insect pests in Brazil and the potential impacts for eucalyptus forestry

BACKGROUND

Brazil is among the world's largest producers of eucalyptus and the damage caused by native and invasive insect pests is one of the main factors affecting eucalyptus yield. The recent history of biological invasions of eucalyptus pests in Brazil prompts demand for phytosanitary measures to prevent new invasions. This study used ecological niche models to estimate suitable areas for nine eucalyptus pests. This information was used to assess the potential ports of entry, generate invasion risk maps considering the likelihood of introducing invasive species, and estimate the eucalyptus producing municipalities and areas within the species' suitable range.

RESULTS

A large distribution range was predicted for Eucalyptolyma maideni (Hempitera: Aphalaridae), Orgya postica (Lepidoptera: Erebidae), Sinoxylon anale (Coleoptera: Bostrichidae), and Trachymela sloanei (Coleoptera: Chrysomelidae) in Brazil, while a comparatively smaller distribution was predicted for Ophelimus maskelli (Hymenoptera: Eulophidae), Mnesampela privata (Lepidoptera: Geometridae), Paropsis atomaria (Coleoptera: Chrysomelidae), Paropsisterna beata, and P. cloelia (Coleoptera: Chrysomelidae). High-risk areas of invasion near airports and seaports were predicted mainly in southern, southeastern, and northeastern Brazil. A large proportion of the municipalities (24.4% to 93.7%) and areas with eucalyptus plantations (31.9% to 98.3%) are within the climatically suitable areas estimated for the pests, especially in southern and southeastern regions, which comprises 61.5% of the Brazilian eucalyptus production.

CONCLUSION

The results indicate that eucalyptus forestry may be significantly impacted by biological invasion. The findings provided by our study can assist decision-makers in developing phytosanitary measures to prevent new invasions of forest pests in Brazil. © 2022 Society of Chemical Industry.

Biological invasions reveal how niche change affects the transferability of species distribution models

Species distribution models (SDMs) have been widely applied to predict geographic ranges of species across space and time under the assumption of niche conservatism (i.e., species niches change very slowly). However, an increasing number of studies have reported evidence of rapid niche changes across space and time, which has sparked a widespread debate on whether SDMs can be transferred to new areas or time periods. Understanding how niche changes affect SDM transferability is thus crucial for the future application and improvement of SDMs. Biological invasions provide an opportunity to address this question due to the geographically independent distributions and diverse patterns of niche changes between species' native and introduced ranges. Here, we synthesized findings about 217 species from 50 studies to elucidate the effects of niche change on the spatial transferability of SDMs. When niche change was considered as a categorical classification (conserved vs. shifted niches) in tests of the niche conservatism hypothesis, SDM transferability was markedly lower for species with a shifted niche in their introduced range. When niche change was measured as numerical dynamics between native and introduced niches, SDM transferability was high for species occupying similar environmental conditions in both ranges and low for species with more environmental space remaining unoccupied in the introduced range. Surprisingly, the number of presence points used for developing SDMs turned out to have an even stronger effect on transferability. Our results thus reveal detrimental effects of both niche change and lack of presence points on SDM transferability. It is necessary to consider both niche change and data quality for improving the transferability of SDMs, so that they can better support conservation management and policy decisions.

Patterns of genetic variation on wild pig (Sus scrofa) populations over a complete range of the species in Argentina

In Argentina, wild pigs (Sus scrofa) are represented by wild boars and feral pigs. These populations inhabit a wide territory due to natural dispersion and human translocation. Previous studies in other countries have detected crossbreeding between the different morphotypes, even with domestic pigs. This crossing can lead to introgression of improved traits in the wild population, which would increase the invasive potential and, therefore, the damage to native ecosystems. The aim of this work was to obtain the patterns of genetic variability throughout its current distribution in Argentina, in order to elucidate genetic relationships between wild boar and feral pig populations through the molecular marker control region. For this purpose, studies of genetic variability and population structure were carried out using 377 sequences from Argentinian wild pigs. The high values of haplotype and nucleotide diversity (Hd = 0.866 and π = 0.00959) obtained, and the cluster analyses (SAMOVA and BAPS) could indicate mixing between wild pigs and/or with domestic pigs. The star-like shapes observed in the haplotype network and neutral tests (Fu’s Fs and Tajima’s D) are consistent with a recent population expansion, supporting previous reports that indicate crossbreeding increases invasive potential.

Diet of invasive wild pigs in a landscape dominated by sugar cane plantations

Understanding the mechanisms by which alien species become invasive can assure successful control programs and mitigate alien species’ impacts. The distribution of invasive wild pigs (Sus scrofa) has been sharply expanding throughout all regions of Brazil in the last few years. Here we demonstrate that large monocultural plantations provide the primary resource subsidies to invasive wild pigs in Brazil. We analyzed 106 stomach contents and carbon stable isotopes (δ13C) of 50 hair samples of wild pigs from a population immersed in a landscape dominated by sugar cane agriculture. Stomach contents were dominated by corn (41%), sugarcane (28.5%), vegetal matter (all other vegetation besides crops, 27%), and animal matter (vertebrates and invertebrates, 4%). Bayesian mixing model analysis of δ13C showed that food sources from C4 photosynthetic pathway (represented by corn and sugarcane) accounted for 94% of the long-term diet, while C3 food sources for only 6.2%. Our results indicate that corn and sugar cane are subsidizing the diet of wild pigs and can facilitate the population growth of this invasive species. Given that Brazil is a major agricultural producer and a hotspot of biodiversity, it is extremely concerning that extensive agriculture may accelerate the expansion of this invasive species, resulting in economic losses and cascading effects on natural habitats.

Invasive wild boar’s distribution overlap with threatened native ungulate in Patagonia

Wild boar (Sus scrofa) is one of the most damaging invasive species in the world and can have a profound impact on the distribution of native species. Nevertheless, there still are limitations on the species’ current fine-scale spatial information, which is needed to develop effective management measures. Here, we used Species Distribution Models (SDMs) and niche overlap analysis to estimate potential conflict areas between the wild boar and the native southern pudu (Pudu puda), which is a bioindicator of the forest conservation status within the Nahuel Huapi National Park (NHNP), Argentina. The two species’ environmental niche overlaps by 40%, which results in a wide geographical overlap between wild boar and pudu distributions. The distribution model predicted that the wild boar potential distribution occupies 22% of the national park and overlaps up to 67% with the pudu distribution, which in turn occupies 20% of the park. Based on our models, we classified 12% of the park as extreme management priority areas, because both species are present. High priority areas, where wild boars have the potential to invade but will not overlap with pudu populations, represent 10% of the park. Medium priority areas, where wild boars do not threaten pudu populations, and low priority areas, with no potential presence of either species, are 8% and 68%, respectively. The results of this study show how SDMs developed at local scales can support the management and monitoring of native and invasive species and help guide the allocation of efforts and resources for management actions focused on protected areas.

An approach to assess stress in response to drive hunts using cortisol levels of wild boar (Sus scrofa)

Hunting can easily be linked to stress in wildlife. Drive hunts performed two to three times in one area during the respective hunting period, are thought to decrease the pressure hunting places on wildlife. Nevertheless, the expression of cortisol—one of the main mammalian stress hormones—is considered to have negative impacts on animals’ well-being if expressed excessively, which may occur during some (especially repeated) hunting events. We explored the effect of drive hunts on cortisol levels in wild boar in Lower Saxony, Germany, compared these cortisol levels to reference values given by a similar study, and investigated the effect of age, sex, and pregnancy. Blood collected from wild boar shot on drive hunts was analysed using a radioimmunoassay. As expected, we observed elevated cortisol levels in all samples, however, we still found significant differences between age groups and sexes, as well as an influence of pregnancy on cortisol levels. The effect of drive hunts on cortisol levels appears to be weaker than predicted, while the effects of other variables, such as sex, are distinct. Only half of the evaluated samples showed explicitly increased cortisol levels and no significant differences were found between sampling months and locations. Group living animals and pregnant females showed significantly higher cortisol levels. The impact of hunting is measurable but is masked by natural effects such as pregnancy. Thus, we need more information on stress levels in game species.

Factors affecting the crop damage by wild boar (Sus scrofa) and effects of population control in the Ticino and Lake Maggiore Park (North-western Italy)

Wild boar foraging impacts the crops, pastures, and meadows causing remarkable losses to agricultural income. Protected areas located in plains, such as the Ticino Valley Natural Park, are characterized by the coexistence of important natural habitats and intensive agricultural areas. In the Park, from 2010 to 2017, 49% of the complaints report an event of damage to maize and 43% to meadows. The total expense for reimbursements of the maize amounted to € 439,341.52, with damages concentrated in May, after sowing period and between August and September, during the milky stage of maize. For meadows reimbursements amounted to € 324,768.66, with damage events concentrated in February and March. To reduce damage to crops, the Park administration carried out lethal control of the wild boar population. From 2006 to 2017, the most used control method was culling from hunting hides. In our analysis, we did not find significant relationships between the number of shot boars and the damage amount. The factors that determine the decrease of damage probability to crops are mainly related to human disturbance and the characteristics of the fields. The predictive model of damage risk built comparing damaged and undamaged fields showed a good predictive ability. The population viability analyses showed that it is impossible to obtain a drastic reduction of population with the current harvest rate. By tripling it and focusing on the females and sub-adult a numerical reduction of 50% of the population would be achievable in 7 years and the probability of population survival would be halved in 3 years.

Predicting Hotspots and Prioritizing Protected Areas for Endangered Primate Species in Indonesia under Changing Climate

Simple Summary

Primates play an essential role in human life and its ecosystem. However, Indonesian primates have suffered many threats due to climate change and altered landscapes that lead to extinction. Therefore, primate conservation planning and strategies are important in maintaining their population. We quantified how extensively the protected areas overlapped primate hotspots and how it changes under mitigation and worst-case scenarios of climate change. Finally, we provide protected areas recommendations based on species richness and land-use changes under the worst-case scenario for Indonesian primate conservation planning and management options.

Abstract

Indonesia has a large number of primate diversity where a majority of the species are threatened. In addition, climate change is conservation issues that biodiversity may likely face in the future, particularly among primates. Thus, species-distribution modeling was useful for conservation planning. Herein, we present protected areas (PA) recommendations with high nature-conservation importance based on species-richness changes. We performed maximum entropy (Maxent) to retrieve species distribution of 51 primate species across Indonesia. We calculated species-richness change and range shifts to determine the priority of PA for primates under mitigation and worst-case scenarios by 2050. The results suggest that the models have an excellent performance based on seven different metrics. Current primate distributions occupied 65% of terrestrial landscape. However, our results indicate that 30 species of primates in Indonesia are likely to be extinct by 2050. Future primate species richness would be also expected to decline with the alpha diversity ranging from one to four species per 1 km². Based on our results, we recommend 54 and 27 PA in Indonesia to be considered as the habitat-restoration priority and refugia, respectively. We conclude that species-distribution modeling approach along with the categorical species richness is effectively applicable for assessing primate biodiversity patterns.

Simultaneous estimation of seasonal population density, habitat preference and catchability of wild boars based on camera data and harvest records

Analyses of life history and population dynamics are essential for effective population control of wild mammals. We developed a model for the simultaneous estimation of seasonal changes in three parameters-population density, habitat preference and trap catchability of target animals-based on camera-trapping data and harvest records. The random encounter and staying time model, with no need for individual recognition, is the core component of the model-by combining this model with the catch-effort model, we estimated density at broad spatial scales and catchability by traps. Here, the wild boar population in central Japan was evaluated as a target population. We found that the estimated population density increased after the birth period and then decreased until the next birth period, mainly due to harvesting. Habitat preference changed seasonally, but forests having abandoned fields nearby were generally preferred throughout the season. These patterns can be explained by patterns of food availability and resting or nesting sites. Catchability by traps also changed seasonally, with relatively high values in the winter, which probably reflected changes in the attractiveness of the trap bait due to activity changes in response to food scarcity. Based on these results, we proposed an effective trapping strategy for wild boars, and discussed the applicability of our model to more general conservation and management issues.

Retrospective spatial analysis for African swine fever in endemic areas to assess interactions between susceptible host populations

African Swine Fever (ASF) is one of the most complex and significant diseases from a sanitary-economic perspective currently affecting the world's swine-farming industry. ASF has been endemic in Sardinia (Italy) since 1978, and several control and eradication programmes have met with limited success. In this traditional ASF endemic area, there are three susceptible host populations for this virus sharing the same habitat: wild boar, farmed domestic pigs and non-registered free-ranging pigs (known as "brado" animals). The main goal of this study was to determine and predict fine-scale spatial interactions of this multi-host system in relation to the epidemiology of ASF in the main endemic area of Sardinia, Montes-Orgosolo. To this end, simultaneous monitoring of GPS-GSM collared wild boar and free-ranging pigs sightings were performed to predict interaction indexes through latent selection difference functions with environmental, human and farming factors. Regarding epidemiological assessment, the spatial inter-specific interaction indexes obtained here were used to correlate ASF notifications in wild boar and domestic pig farms. Daily movement patterns, home ranges (between 120.7 and 2,622.8 ha) and resource selection of wild boar were obtained for the first time on the island. Overall, our prediction model showed the highest spatial interactions between wild boar and free-ranging pigs in areas close to pig farms. A spatially explicit model was obtained to map inter-specific interaction over the complete ASF-endemic area of the island. Our approach to monitoring interaction indexes may help explain the occurrence of ASF notifications in wild boar and domestic pigs on a fine-spatial scale. These results support the recent and effective eradication measures taken in Sardinia. In addition, this methodology could be extrapolated to apply in the current epidemiological scenarios of ASF in Eurasia, where exist multi-host systems involving free-ranging pigs and wild boar.

Evidence of ecological niche shift in Rhododendron ponticum (L.) in Britain: Hybridization as a possible cause of rapid niche expansion

Biological invasions threaten global biodiversity and natural resources. Anticipating future invasions is central to strategies for combating the spread of invasive species. Ecological niche models are thus increasingly used to predict potential distribution of invasive species. In this study, we compare ecological niches of Rhododendron ponticum in its native (Iberian Peninsula) and invasive (Britain) ranges. Here, we test the conservation of ecological niche between invasive and native populations of R. ponticum using principal component analysis, niche dynamics analysis, and MaxEnt-based reciprocal niche modeling. We show that niche overlap between native and invasive populations is very low, leading us to the conclusion that the two niches are not equivalent and are dissimilar. We conclude that R. ponticum occupies novel environmental conditions in Britain. However, the evidence of niche shift presented in this study should be treated with caution because of nonanalogue climatic conditions between native and invasive ranges and a small population size in the native range. We then frame our results in the context of contradicting genetic evidence on possible hybridization of this invasive species in Britain. We argue that the existing contradictory studies on whether hybridization caused niche shift in R. ponticum are not sufficient to prove or disprove this hypothesis. However, we present a series of theoretical arguments which indicate that hybridization is a likely cause of the observed niche expansion of R. ponticum in Britain.

Global distribution modelling, invasion risk assessment and niche dynamics of Leucanthemum vulgare (Ox-eye Daisy) under climate change

In an era of climate change, biological invasions by alien species represent one of the main anthropogenic drivers of global environmental change. The present study, using an ensemble modelling approach, has mapped current and future global distribution of the invasive Leucanthemum vulgare (Ox-eye Daisy) and predicted the invasion hotspots under climate change. The current potential distribution of Ox-eye Daisy coincides well with the actual distribution records, thereby indicating robustness of our model. The model predicted a global increase in the suitable habitat for the potential invasion of this species under climate change. Oceania was shown to be the high-risk region to the potential invasion of this species under both current and future climate change scenarios. The results revealed niche conservatism for Australia and Northern America, but contrastingly a niche shift for Africa, Asia, Oceania and Southern America. The global distribution modelling and risk assessment of Ox-eye Daisy has immediate implications in mitigating its invasion impacts under climate change, as well as predicting the global invasion hotspots and developing region-specific invasion management strategies. Interestingly, the contrasting patterns of niche dynamics shown by this invasive plant species provide novel insights towards disentangling the different operative mechanisms underlying the process of biological invasions at the global scale.

Assessment of microbial communities on freshly killed wild boar meat by MALDI-TOF MS and 16S rRNA amplicon sequencing

Wild boars (Sus scrofa) are the most widely distributed large mammals and recent increase in consumption of wild boar meat urges the need of microbiological quality criteria. The aim of the study was to characterize the initial bacterial contamination on freshly-killed wild boar meat using a culture-dependent approach with ISO-methods combined with matrix-assisted laser desorption/ionization time-of-flight mass spectrometry identification and 16S rRNA amplicon sequencing. Moreover, the presence of foodborne pathogens was examined using Real-Time-PCR and confirmed by classical isolation. Analysing 22 unrelated wild boar meat samples showed a higher bacterial contamination level compared to pork, with Salmonella present in almost one third of the samples. A great variability of the microbial contamination between the samples was recorded, as well as complementary results between culturing and 16S rRNA amplicon sequencing as frequently isolated genera were not always detected, and vice versa. Furthermore, the foodborne pathogen Salmonella was never detected with 16S rRNA amplicon sequencing, demonstrating the necessity for a cautious approach in the implementation of new analysis techniques in food safety. The present work determines that attention should be paid to the trade of non-inspected meat directly to retail or consumers.

Wild pig (Sus scrofa L.) occupancy patterns in the Brazilian Atlantic forest

Abstract: Despite the great impacts of invasive wild pig (Sus scrofa) to natural ecosystems, habitat use by this species in the neotropics remains poorly studied. Here, we investigated the effects of local habitat and landscape covariates (vegetation types, running watercourses and roads) on occupancy patterns of wild pig in the Atlantic Forest of southern Brazil. We used single season occupancy modeling to estimate detection (p) and occupancy (ψ) probabilities, using 8-day camera-trap monitoring of 100 sampled sites. The cameras detected wild pig in 64 sites (naïve occupancy = 64 %). The four best models explained 72.7 % of the occupancy patterns, and the top model (with "water" variable) had a weight of 28.5 %. Even though none of the tested variables had high explanatory power of wild pig occupancy, the water variable had a negative effect trend (β = -1.124; SE = 0.734), with 59 % of occupancy when water was present and 82 % when it was absent around the sampling sites. Vestiges of the presence of wild pig in different vegetation types revealed that they used plantations of Pinus sp., native forests, and corn and oat crops. The occupation pattern shows that wild pig are generalist at our study site at the Atlantic Forest being found everywhere, raising ecological and economic concerns about the high potential negative effects of its invasion.

Field evaluation of low-dose warfarin baits to control wild pigs (Sus scrofa) in North Texas

Wild pigs (Sus scrofa) are a highly detrimental invasive species that occupy a rapidly expanding range within the United States. In Australia, field trials evaluating baits containing 0.09% warfarin resulted in wild pig population reduction >95%. The objective of this study was to conduct an EPA-approved field trial to evaluate the use of bait containing low-dose warfarin (0.01% and 0.005%) in reducing wild pig numbers in Texas. An 8-week field test was conducted in the panhandle ~100 km southeast of Amarillo. Two ~8 km² treatment plots were selected and each presented with either 0.01% or 0.005% warfarin baits. One control plot (~8 km²) was presented placebo. The baits were delivered using 30 species-specific feeders per plot (n = 90) that kept wildlife from accessing the toxicant. Pig movements and feed consumption were monitored during pre-treatment, treatment, and post-treatment periods. All pigs with VHF transmitters within the 0.005% warfarin-treated plot (n = 14) succumbed to the warfarin (100% mortality). Overall, 35 wild pigs were found dead from warfarin toxicosis, within both treatment plots. Total feed consumption by wild pigs was reduced by ~97.8% and ~96.2% for the 0.005% and 0.01% warfarin baited plots, respectively, indicating the absence of pigs was a result of toxic bait consumption. Results of 97 systematic searches of the treatment plots indicated no warfarin-induced non-target wildlife fatalities. Warfarin residues in wild pig livers averaged 3.69 mg/kg (n = 13) and 2.89 mg/kg (n = 9) for pigs recovered within the 0.005% plot and 0.01% warfarin plot, respectively. This study is the first efficacy field evaluation of a wild pig toxicant conducted in the US. The results suggest low-dose warfarin bait, presented in species-specific feeders, can effectively reduce wild pig numbers and pose minimal risk to non-target wildlife and domestic animals. A product containing warfarin may provide another management tool in reducing wild pig problems.

Wild boar mapping using population-density statistics: From polygons to high resolution raster maps

The wild boar is an important crop raider as well as a reservoir and agent of spread of swine diseases. Due to increasing densities and expanding ranges worldwide, the related economic losses in livestock and agricultural sectors are significant and on the rise. Its management and control would strongly benefit from accurate and detailed spatial information on species distribution and abundance, which are often available only for small areas. Data are commonly available at aggregated administrative units with little or no information about the distribution of the species within the unit. In this paper, a four-step geostatistical downscaling approach is presented and used to disaggregate wild boar population density statistics from administrative units of different shape and size (polygons) to 5 km resolution raster maps by incorporating auxiliary fine scale environmental variables. 1) First a stratification method was used to define homogeneous bioclimatic regions for the analysis; 2) Under a geostatistical framework, the wild boar densities at administrative units, i.e. subnational areas, were decomposed into trend and residual components for each bioclimatic region. Quantitative relationships between wild boar data and environmental variables were estimated through multiple regression and used to derive trend components at 5 km spatial resolution. Next, the residual components (i.e., the differences between the trend components and the original wild boar data at administrative units) were downscaled at 5 km resolution using area-to-point kriging. The trend and residual components obtained at 5 km resolution were finally added to generate fine scale wild boar estimates for each bioclimatic region. 3) These maps were then mosaicked to produce a final output map of predicted wild boar densities across most of Eurasia. 4) Model accuracy was assessed at each different step using input as well as independent data. We discuss advantages and limits of the method and its potential application in animal health.

Epidemiological analyses of African swine fever in the Baltic States and Poland: (Update September 2016-September 2017)

EFSA assisted four countries in the analysis of epidemiological data on African swine fever (ASF), collected until September 2017. The temporal analysis demonstrated that the average proportions of PCR and antibody‐ELISA positive samples from the hunted wild boar remained below 3.9 and 6.6, respectively. A peak in the ASF incidence was observed 6 months after the first observed case, followed by a significant reduction of the number of cases and low levels of African swine fever virus (ASFV) circulation at the end of 38 months follow‐up period at different spatial resolutions. The spatial analysis concluded that human‐mediated spread of ASFV continues to play a critical role in the ASF epidemiology, despite all measures currently taken. ‘Wild boar density’, ‘total road length’ (as proxy for human activity) and ‘average suitable wild boar habitat availability’ were identified as predictors for the occurrence of ASF in Estonia by a Bayesian hierarchical model, whereas ‘wild boar density’ and ‘density of pig farms’ were predictors according to a generalised additive model. To evaluate the preventive strategies proposed in EFSA's Scientific Opinion (2015) to stop the spread of ASFV in the wild boar population, a simulation model, building on expert knowledge and literature was used. It was concluded that reduction of wild boar population and carcass removal to stop the spread of ASFV in the wild boar population are more effective when applied preventively in the infected area. Drastic depopulation, targeted hunting of female wild boar and carcass removal solely implemented as measures to control ASF in the wild boar population need to be implemented in a highly effective manner (at or beyond the limit of reported effectivity in wild boar management) to sustainably halt the spread of ASF.

This publication is linked to the following EFSA Supporting Publications article: http://onlinelibrary.wiley.com/doi/10.2903/sp.efsa.2017.EN-1312/full