Exposure of a population of invasive wild pigs to simulated toxic bait containing biomarker: implications for population reduction

BACKGROUND: An international effort to develop an acute and humane toxic bait for invasive wild pigs (Sus scrofa) is underway to curtail their expansion. We evaluated the ability to expose a population of wild pigs to a simulated toxic bait (i.e., placebo bait containing a biomarker, rhodamine B, in lieu of the toxic ingredient) to gain insight on potential population reduction. We used 28 GPS-collars and sampled 428 wild pigs to examine their vibrissae for evidence of consuming the bait. RESULTS: We estimated that 91% of wild pigs within 0.75 km of bait sites (total area = 16.8 km2) consumed the simulated toxic bait, exposing them to possible lethal effects. Bait sites spaced 0.75–1.5 km apart achieved optimal delivery of the bait, but wild pigs ranging ≥ 3 km away were susceptible. Use of wild pig-specific bait stations resulted in no non-target species directly accessing the bait. CONCLUSION: Results demonstrate the potential for exposing a large proportion of wild pigs to a toxic bait in similar ecosystems. Toxic bait may be an effective tool for reducing wild pig populations especially if used as part of an integrated pest management strategy. Investigation of risks associated with a field-deployment of the toxic bait is needed

Comparison of the efficacy of four drug combinations for immobilization of wild pigs

Field immobilization of native or invasive wild pigs (Sus scrofa) is challenging. Drug combinations commonly used often result in unsatisfactory immobilization, poor recovery, and adverse side effects, leading to unsafe handling conditions for both animals and humans. We compared four chemical immobilization combinations, medetomidine–midazolam–butorphanol (MMB), butorphanol–azaperone–medetomidine (BAM™), nalbuphine–medetomidine–azaperone (NalMed-A), and tiletamine– zolazepam–xylazine (TZX), to determine which drug combinations might provide better chemical immobilization of wild pigs. We achieved adequate immobilization with no post-recovery morbidity withMMB. Adequate immobilization was achieved with BAM™; however, we observed post-recovery morbidity. Both MMB and BAM™ produced more optimal results relative to body temperature, recovery, and post-recovery morbidity and mortality compared to TZX. Adequate immobilization was not achieved with NalMed-A. Of the four drug combinations examined, we conclude that MMB performed most optimally for immobilization and recovery of wild pigs

HLA-DPA1*02:01~B1*01:01 is a risk haplotype for primary sclerosing cholangitis mediating activation of NKp44+ NK cells

Objective Primary sclerosing cholangitis (PSC) is characterised by bile duct strictures and progressive liver disease, eventually requiring liver transplantation. Although the pathogenesis of PSC remains incompletely understood, strong associations with HLA-class II haplotypes have been described. As specific HLA-DP molecules can bind the activating NK-cell receptor NKp44, we investigated the role of HLA-DP/NKp44-interactions in PSC. Design Liver tissue, intrahepatic and peripheral blood lymphocytes of individuals with PSC and control individuals were characterised using flow cytometry, immunohistochemical and immunofluorescence analyses. HLA-DPA1 and HLA-DPB1 imputation and association analyses were performed in 3408 individuals with PSC and 34 213 controls. NK cell activation on NKp44/HLA-DP interactions was assessed in vitro using plate-bound HLA-DP molecules and HLA-DPB wildtype versus knock-out human cholangiocyte organoids. Results NKp44+NK cells were enriched in livers, and intrahepatic bile ducts of individuals with PSC showed higher expression of HLA-DP. HLA-DP haplotype analysis revealed a highly elevated PSC risk for HLA-DPA1*02:01~B1*01:01 (OR 1.99, p=6.7×10-50). Primary NKp44+NK cells exhibited significantly higher degranulation in response to plate-bound HLA-DPA1*02:01-DPB1*01:01 compared with control HLA-DP molecules, which were inhibited by anti-NKp44-blocking. Human cholangiocyte organoids expressing HLA-DPA1*02:01-DPB1*01:01 after IFN-γ-exposure demonstrated significantly increased binding to NKp44-Fc constructs compared with unstimulated controls. Importantly, HLA-DPA1*02:01-DPB1*01:01-expressing organoids increased degranulation of NKp44+NK cells compared with HLA-DPB1-KO organoids. Conclusion Our studies identify a novel PSC risk haplotype HLA-DP A1*02:01~DPB1*01:01 and provide clinical and functional data implicating NKp44+NK cells that recognise HLA-DPA1*02:01-DPB1*01:01 expressed on cholangiocytes in PSC pathogenesis

Daily and Landscape Influences of Species Visitation to Toxic Bait Sites for Wild Pigs

Toxic baiting of wild pigs (Sus scrofa) is a potential new tool for population control and damage reduction in the United States. Use of toxic bait sites by non‐target species is concerning because of the risks posed from exposure to a toxic bait. A 2018 field trial in northern Texas, USA, examining the efficacy of a prototype toxic bait (HOGGONE®, containing 10% sodium nitrite) revealed unexpected hazards to non‐target species, primarily passerine birds, from consuming toxic bait spilled outside of bait stations by wild pigs. The hazards jeopardize the ability to register HOGGONE as a tool for controlling wild pigs. We conducted a post hoc analysis from that 2018 trial to identify how daily and landscape factors influenced the use of bait sites by non‐target species, and subsequent hazards from consuming the toxic bait. We discovered that no single strategy can eliminate visitations by all non‐target species, but offering the toxic bait at night, in wild‐pig specific bait stations, and in more homogeneous landscapes appeared to be the best strategy for minimizing visits by passerine birds. We also found that use of bait sites by wild pigs were temporally clustered, and more pigs visited bait sites along linear features of the landscape (e.g., agricultural edges or riparian corridors). We recommend a baiting strategy where applicators do not place bait stations directly at sites where remnant particles of grain (from prebaiting) are available on the ground

Improved Strategies for Handling Entire Sounders of Wild Pigs

As wild pigs (Sus scrofa) expand throughout North America researchers are increasingly being tasked with trapping and marking entire sounders (family groups) to attach monitoring devices or other identifying markers to gather knowledge to inform management. Capture and marking procedures can be challenging, dangerous for both researchers and animals, and time consuming, particularly when handling sounders. We developed an integrated pig‐handling system to efficiently sort, weigh, chemically immobilize, and mark multiple wild pigs simultaneously in a controlled manner. To assess the functionality of the system, we evaluated 18 capture events in Texas, USA, from January 2018 to March 2019, where we marked 221 pigs of varied age classes and group sizes (2–19 animals). Using the pig‐handling system, we chemically immobilized 51 large (41–101 kg) pigs and manually restrained 170 smaller (\u3c45 kg) pigs with injury rates below 4%. Average handling times for large pigs was 71.9 (SD = 25.7) min and \u3c1 min for smaller ones. We released sounders intact and routinely recorded them together on motion‐activated cameras. Incorporating a handling system into wild pig research and management is encouraged to facilitate safe handling procedures for both pigs and handlers

Exposure of a population of invasive wild pigs to simulated toxic bait containing biomarker: implications for population reduction

BACKGROUND: An international effort to develop an acute and humane toxic bait for invasive wild pigs (Sus scrofa) is underway to curtail their expansion. We evaluated the ability to expose a population of wild pigs to a simulated toxic bait (i.e., placebo bait containing a biomarker, rhodamine B, in lieu of the toxic ingredient) to gain insight on potential population reduction. We used 28 GPS-collars and sampled 428 wild pigs to examine their vibrissae for evidence of consuming the bait. RESULTS: We estimated that 91% of wild pigs within 0.75 km of bait sites (total area = 16.8 km2) consumed the simulated toxic bait, exposing them to possible lethal effects. Bait sites spaced 0.75–1.5 km apart achieved optimal delivery of the bait, but wild pigs ranging ≥ 3 km away were susceptible. Use of wild pig-specific bait stations resulted in no non-target species directly accessing the bait. CONCLUSION: Results demonstrate the potential for exposing a large proportion of wild pigs to a toxic bait in similar ecosystems. Toxic bait may be an effective tool for reducing wild pig populations especially if used as part of an integrated pest management strategy. Investigation of risks associated with a field-deployment of the toxic bait is needed