Wild Populations Research Articles

A practical approach to meeting national obligations for sustainable trade under CITES.

Reconciling conservation goals with sustainable resource use requires adaptive management strategies. The Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES) regulates global trade for species listed on Appendix II, partly by requiring member countries (parties) to ensure exports do not damage wild populations (called making positive "nondetriment findings" [NDFs]). Unfortunately, when parties find NDFs difficult, they often suspend legal trade, imposing economic costs and driving trade underground. To make it easier for parties to examine the detrimental nature of exports, we devised a spatial approach and applied it to seahorses (Hippocampus spp.) in Tamil Nadu, India, as an example. Our approach involves mapping answers to 5 key questions on species distribution (QA), pressures (QB), management measures (QC), management implementation (QD), and species' population status (QE). We gathered data from fisher interviews and published literature. Seahorse abundance was greatest in southern Palk Bay and the northern Gulf of Mannar, primarily in seagrasses and coral reefs (QA). Fishing pressure was highest in Palk Bay, primarily from bottom trawlers and dragnetters operating in shallow seahorse habitats near the coastline (QB). Management measures including a marine protected area (MPA), bottom trawl exclusion zone, and closed season were theoretically in place (QC), but their implementation was poor (QD). Fishers reported seahorse catches in 85% of the area covered by the MPA and the exclusion zone; bottom trawlers were responsible for most violations. Seahorses were also captured in Sri Lankan waters, where bottom trawling is banned. Fisher reports indicated declining seahorse catches and reduced body sizes (QE), highlighting unsustainable exploitation. Our results highlight the need for better implementation of existing management measures before a positive NDF can be made and suggest mitigation beyond bans. Such pragmatic spatial analyses can help regulate exports at sustainable levels, supporting CITES implementation for its vast range of species.

The feeding preference and bite response between Microtus fortis and Broussonetia papyrifera.

Broussonetia papyrifera is a dioecious plant that is rich in various metabolites and widely distribute in Asia. Microtus fortis is a rodent that often causes damage to crops, especially in the Dongting Lake region of China. There is a wide overlap in the distribution areas for the above species and the M. fortis feeds on the leaves of the B. papyrifera. Preliminary experiments have shown that the reproduction of M. fortis is inhibited after feeding on the leaves of the B. papyrifera. In order to explore the potential of using B. papyrifera to develop botanical pesticides, we investigated the palatability and reactive substances. The feeding frequency of M. fortis on B. papyrifera leaves to that of on daily fodder and Carex brevicuspis that is the primary food for the wild population were compared. We also attempted to identify the responsive substances in B. papyrifera leaves that were bitten by M. fortis using metabolome analysis. In general, B. papyrifera leaves exhibited a stronger attraction to M. fortis. M. fortis foraged B. papyrifera leaves more frequently, and the intake was higher than that of the other two. Differential metabolites were screened by comparing normal leaves and leaves bitten by M. fortis, meanwhile with the intervention of clipped leaves. A total of 269 substances were screened, and many of these were involved in the biosynthesis of secondary metabolites, including terpenoids and alkaloids. These substances may be related to the defense mechanism of B. papyrifera against herbivores. These findings support further research examining animal-plant interactions and simultaneously provide insights into the utilisation of B. papyrifera resources and the management of rodents. The good palatability and the defense of B. papyrifera leaves suggest that they have the potential to contribute in development of plant rodenticide.

Prevalence of Aleutian Mink Disease Virus (AMDV) in Free-Ranging American Mink from Biebrza and Narew National Parks (Poland)-An Epidemiological Concern.

Aleutian Mink Disease Virus (AMDV) is the causative agent of Aleutian disease (AD). This progressive and chronic disorder significantly impacts the mink breeding industry, affecting farmed and free-ranging American and European mink. This study investigated AMDV variants isolated from free-ranging American mink in northeastern Poland. Between 2018 and 2019, 26 spleen samples were collected from mink in Narew National Park (NNP) and Biebrza National Park (BNP). DNA was extracted and subjected to PCR to amplify the NS1 gene, followed by sequencing and phylogenetic analysis. The NS1 gene was detected in 50% of samples from NNP minks and in 30% of samples from BNP minks, with an overall prevalence of 42.31%; these findings align with global data and indicate serious ecological and health concerns. Ten closely related AMDV variants and one distinct variant were identified. The grouped variants exhibited high genetic homogeneity, closely related to strains found in mink from the USA, Germany, Greece, Latvia, and Poland; meanwhile, the distinct variant showed similarities to strains found in mink from Finland, Denmark, China, Poland, and Latvia, suggesting multiple infection sources. These findings, consistent with data from Polish mink farms, indicate significant genetic similarity between farmed and wild mink strains, suggesting potential bidirectional transmission. This underscores the importance of a One Health approach, emphasizing the interconnectedness of human, animal, and environmental health. Continuous surveillance and genetic studies are crucial for understanding AMDV dynamics and mitigating their impacts. Measures to reduce transmission between farmed and wild mink populations are vital for maintaining mink health and ecosystem stability.

Genomic Diversity and Evolutionary Insights of Avian Paramyxovirus-1 in Avian Populations in Pakistan.

The virulent form of Avian paramyxovirus-1 (APMV-1), commonly known as Newcastle Disease Virus (NDV), is a pathogen with global implications for avian health, affecting both wild and domestic bird populations. In Pakistan, recurrent Newcastle Disease (caused by NDV) outbreaks have posed significant challenges to the poultry industry. Extensive surveillance in Pakistan over 20 years has demonstrated a dynamic genetic diversity among circulating APMV-1 strains, emphasizing the potential necessity for customized vaccination strategies and continuous surveillance. In this study, 13 APMV-1-positive isolates harboring four different APMV-1 genotypes circulating throughout Pakistan were identified. These included the highly virulent genotypes VII and XIII, genotype XXI, commonly associated with Columbiformes, and genotype II, hypothesized to have been detected following vaccination. These findings underscore the intricate interplay of mutational events and host-immune interactions shaping the evolving NDV landscape. This study advances our understanding of the evolutionary dynamics of APMV-1 in Pakistan, highlighting the need for tailored vaccination strategies and continuous surveillance to enable effective APMV-1 management in avian populations, further emphasizing the importance of globally coordinated strategies to tackle APMV-1, given its profound impact on wild and domestic birds.

The Effect of Age on Survival Is Similar in Males and Females of an Aquatic Insect Species

Age is a critical intrinsic factor that influences the probability of survival of organisms on Earth. In many animals, the lifestyles and habitat occupancy of males and females are so different that the effect of age could be sex-dependent. To reveal such patterns in wild animal populations, we here use a natural population of the Mediterranean demoiselle Calopteryx haemorrhoidalis Vander Linden (Calopterygidae: Zygoptera) in Northeast Algeria to analyze the influence of age and sex on survival probability using daily capture–mark–recapture. We used stepwise model selection on Cormack–Jolly–Seber models that explain recapture and survival probability, including age and sex as covariates. We marked a total of 214 adults throughout the study period (41 days). The sex ratio did not deviate from unity. Recapture probability depended on sex and time, with a slightly higher recapture probability in males (0.30 [95% CI: 0.27–0.35]) than females (0.26 [0.22–0.30]). The survival probability was slightly higher in females (0.89 [0.86–0.91]) than males (0.86 [0.82–0.88]). The best model for the survival probability included an additive effect of sex and age, indicating that the survival probability of both sexes declined with age. Interestingly, the lifespan of some individuals reached 119–130 days, which is surprisingly long compared to other temperate damselflies.

Prevalence and seasonal variation of Olpidiopsis porphyrae (Oomycota) infecting red algal Bangiales from the Southern Pacific

ABSTRACT The Bangiales are one of the most common seaweeds in sub-Antarctic and Southeastern Pacific upper intertidal habitats. Here we report records of an ‘olpidioid’ marine obligate parasite infecting Bangiales between 39°20′–41°44′S in the Southeastern Pacific for the first time. The disease resembles the ‘Olpidiopsis blight disease’ reported for farmed Bangiales in Japan and Korea and wild Pyropia from Scotland morphologically and developmentally. The Chilean isolate infects commercial Chilean laver or ‘luche’ (Porphyra sensu lato) and Bangia sensu lato from wild populations in the Southeastern Pacific. Phylogenetic markers (cox2, 18S) identify it as Olpidiopsis porphyrae. We relate the occurrence of this pathogen to both ‘luche’ fisheries in Chile and the potential consequences for its emergent aquaculture in the Southeastern Pacific.

Detecting context dependence in the expression of life history trade-offs.

Life history trade-offs are one of the central tenets of evolutionary demography. Trade-offs, depicting negative covariances between individuals' life history traits, can arise from genetic constraints, or from a finite amount of resources that each individual has to allocate in a zero-sum game between somatic and reproductive functions. While theory predicts that trade-offs are ubiquitous, empirical studies have often failed to detect such negative covariances in wild populations. One way to improve the detection of trade-offs is by accounting for the environmental context, as trade-off expression may depend on environmental conditions. However, current methodologies usually search for fixed covariances between traits, thereby ignoring their context dependence. Here, we present a hierarchical multivariate 'covariance reaction norm' model, adapted from Martin (2023), to help detect context dependence in the expression of life-history trade-offs using demographic data. The method allows continuous variation in the phenotypic correlation between traits. We validate the model on simulated data for both intraindividual and intergenerational trade-offs. We then apply it to empirical datasets of yellow-bellied marmots (Marmota flaviventer) and Soay sheep (Ovis aries) as a proof-of-concept showing that new insights can be gained by applying our methodology, such as detecting trade-offs only in specific environments. We discuss its potential for application to many of the existing long-term demographic datasets and how it could improve our understanding of trade-off expression in particular, and life history theory in general.

Evidence of a twofold ecological trap driven by agricultural change causing a priority farmland bird population crash

AbstractExtensive farmland in Europe hosts high biodiversity levels but is threatened by land use changes associated with market and agricultural policy drivers. We show that a nationwide replacement of rainfed cereals in favor of beef production in Portugal has coincided with a nearly 80% decline in the population of a ground‐nesting raptor, the Montagu's harrier Circus pygargus, since 2002. Reduced cereal crop cover led to nesting attempts occurring mostly in fodder crops, the predominant habitat with suitable sward structure at the onset of breeding. This results in a twofold ecological trap: early hay harvesting destroys first nesting attempts, whereas late cereal harvesting destroys replacement clutches. This double phenological mismatch prevents any breeding success and likely explains the country's observed population decline of Montagu's harriers and other key farmland birds. Reforming current agroenvironmental schemes to promote practices compatible with wild population phenology is paramount to revert these changes.

36-year study reveals stability of a wild wheat population across microhabitats.

Long-term genetic studies of wild populations are very scarce, but are essential for connecting ecological and population genetics models, and for understanding the dynamics of biodiversity. We present a study of a wild wheat population sampled over a 36-year period at high spatial resolution. We genotyped 832 individuals from regular sampling along transects during the course of the experiment. Genotypes were clustered into ecological microhabitats over scales of tens of metres, and this clustering was remarkably stable over the 36 generations of the study. Simulations show that it is difficult to determine whether this spatial and temporal stability reflects extremely limited dispersal or fine-scale local adaptation to ecological parameters. Using a common-garden experiment, we showed that the genotypes found in distinct microhabitats differ phenotypically. Our results provide a rare insight into the population genetics of a natural population over a long monitoring period.

CASE-CONTROL STUDY OF THE FREQUENCY AND ETIOLOGY OF ATAXIA IN ASIATIC LIONS (PANTHERA LEO PERSICA) BETWEEN 2002 AND 2020.

The Asiatic lion (Panthera leo persica) is an endangered species with a slowly increasing captive and wild population. Several zoos from within the European Association of Zoos and Aquaria Ex Situ Program reported Asiatic lions with neurological signs such as (progressive) ataxia, and stargazing. The aim of this study was to evaluate the frequency (prevalence and incidence) and etiology of these clinical signs within the captive Asiatic lion population. The medical history of 74 Asiatic lions (36 healthy and 38 affected) was retrieved and reviewed for blood tests (biochemical, hematological, and retinol), diagnostic imaging (MRI and CT scans) and postmortem examinations. The data of the affected lions was compared with those of healthy lions. Between 2002 and 2020, the prevalence of ataxia ranged from 0.6% in 2004 to 13.0% in 2020. The incidence of ataxia was variable per year between 2002 and 2020 and ranged between 0 and 40%. Besides ataxia, stiffness and lameness were the most described signs in this study. Blood results showed lower total protein, ALT and creatinine, and higher phosphate in lions with neurological signs. Moreover, neurologically affected lions showed a significant lower blood retinol than the control lions (0.59-0.81 µmol/L). The most important finding in diagnostic imaging and necropsy included caudal fossa hyperostosis and cerebellar herniation. These abnormalities are similar as found in African lions (Panthera leo) with calvarial hyperostosis syndrome associated with vitamin A deficiency. Leucomyelopathy, syringomyelia (in one case combined with cerebellar herniation) and incidental mineralization of the dura mater were also described. A possible congenital/hereditary component should not be excluded.

Development of eDNA Protocols for Detection of Endangered White Sturgeon (Acipenser transmontanus) in the Wild

ABSTRACTUnderstanding the distribution and habitat use of endangered species is essential for conservation efforts. Environmental DNA (eDNA) analysis has become a more common approach to defining species habitat occupancy through identification of residual DNA in water samples and has potential to detect populations that are in low abundance or use habitats over a large geographical range. Here, we optimized an eDNA protocol to detect the presence of the endangered white sturgeon (Acipenser transmontanus). We implemented lab‐based experiments to understand the sensitivity and persistence of white sturgeon eDNA and then applied these methods to habitats with known white sturgeon abundances categorized as high, low, or not present. Using quantitative PCR (qPCR) and a modified StrAci1N‐flap primer set, white sturgeon eDNA was detected in water collected from tanks holding white sturgeon down to a dilution of 10,000× (estimated eDNA concentration of 0.00035 μg/L—0.00176 μg/L). Following the removal of white sturgeon from the tanks, the eDNA signal decreased with time but could be detected for up to 7 days. In the field, all sites with high abundances of white sturgeon returned positive eDNA detections. We did not detect white sturgeon eDNA at sites with low abundance or in areas where they were not expected to be present. Results from this work further advance our interpretation of eDNA from wild populations and provide a noninvasive method to advance recovery efforts by identifying species presence in areas of suspected use or to guide additional inventory efforts.

RHDV2 outbreak reduces survival and juvenile recruitment, causing European rabbit population collapse

AbstractInfectious diseases can cause considerable mortality in vertebrate populations, especially when a new pathogen emerges. Quantifying the impact of diseases on wild populations and dissecting the underlying mechanisms requires longitudinal individual monitoring combining demographic and epidemiologic data. Such longitudinal population studies are rare. Rabbit hemorrhagic disease (RHD) is one of the main causes of the decline in European wild rabbit (Oryctolagus cuniculus) populations. A new genotype of RHD virus (RHDV), called RHDV2 or GI.2, emerged in 2010, posing a new threat to previously weakened populations, particularly as this virus can infect individuals already immune to classical RHDV strains. Taking advantage of intensive monitoring from 2009 to 2014 by physical captures and microchip detections of a semi‐captive population of rabbits, we finely assessed the demographic impact of an initial RHDV2 outbreak that occurred in the population and identified the most affected demographic parameters. A multi‐event modeling analysis revealed decreased survival in both juveniles and adults in 2011 and 2012, suggesting an RHDV2 outbreak for two consecutive years. The short‐term survival benefit of vaccination against classical RHDV strains only during these years, and the recovery of carcasses with RHDV2 detection, supported this hypothesis. Variations in population vaccination coverage also explain the difference in adult survival between the two years of the outbreak. And the transient protective effect of vaccination could explain the prolonged duration of the outbreak. A brief episode of myxomatosis in 2011 seems to have had only a limited impact on the population. During outbreak years, in individuals not recently vaccinated, monthly juvenile survival crashed (0.55), and annual adult survival was three times lower than in normal years (0.21 vs. 0.69). The combination of successive juvenile and adult survival estimates for unvaccinated rabbits during the outbreak years resulted in a very low recruitment rate in the breeding population. Finally, RHDV2 outbreaks appear to have caused mortalities comparable to those caused by older classical RHDV strains and may have a strong demographic impact on wild populations of European rabbit. This work highlights the importance of long‐term observational and experimental studies to better understand the impact of epidemics on animal populations.

Wild bird mass mortalities in eastern Canada associated with the Highly Pathogenic Avian Influenza A(H5N1) virus, 2022

AbstractIn 2022, a severe outbreak of disease caused by clade 2.3.4.4b Highly Pathogenic Avian Influenza (HPAI) H5N1 virus resulted in unprecedented mortality among wild birds in eastern Canada. Tens of thousands of birds were reported sick or dead, prompting a comprehensive assessment of mortality spanning the breeding season between April 1 and September 30, 2022. Mortality reports were collated from federal, Indigenous, provincial, and municipal agencies, the Canadian Wildlife Health Cooperative, and other nongovernmental organizations, universities, and citizen science platforms. A scenario analysis was conducted to refine mortality estimates, accounting for potential double counts from multiple sources under a range of spatial and temporal overlaps. Correcting for double counting, HPAI is estimated to have caused 40,391 wild bird mortalities in eastern Canada during the spring and summer of 2022; however, this figure underestimates total mortality as it excludes unreported deaths on land and at sea. Seabirds and sea ducks, long‐lived species that are slow to recover from perturbations, accounted for 98.7% of estimated mortalities. Our study provides estimates of bird mortality, with Northern Gannets (Morus bassanus; 25,669), Common Murres (Uria aalge; 8133), and American Common Eiders (Somateria mollissima dresseri; 1894) exhibiting the highest mortality figures. We then compare these mortality estimates with recent population estimates and trends and make an initial assessment of whether biologically meaningful population‐level impacts are possible. Specifically, we focus on the Northern Gannet, a species that has suffered significant global mortality, and two harvested species, Common Murre and American Common Eider, to inform management decisions. Our analysis suggests population‐level impacts in eastern Canada are possible for Northern Gannets and American Common Eiders, but are unlikely for Common Murres. This study demonstrates a comprehensive approach to assessing mortality and underscores the urgent need for further research to understand the broader ecological ramifications of the HPAI outbreak on wild bird populations.

First Histopathological and Molecular Characterization of Giant Thorny-headed Worm, Macracanthorhynchus hirudinaceus (Pallas, 1781) (Acanthocephala: Oligacanthorhynchidae) in Wild Boars, Sus scrofa Linnaeus, 1758 from Eastern Türkiye.

Macracanthorhynchus hirudinaceus (Pallas, 1781) is a zoonotic acanthocephalan that parasitizes the small intestine of wild boars. It is a pathogenic that causes economic losses, and poses a public health threat due to increased emergence. The aims of this study is describes histopathologically the damage caused by M. hirudinaceus in the small intestine of wild boar Sus scrofa Linnaeus, 1758, and molecularly characterize this parasite (sequences, haplotypes, phylogeny) for the first time in Elazig city, Türkiye. A high prevalence of infection was obtained. Upon separating the worms, it was discovered that there were ulcers resembling craters in the center, of the small intestine mucosa, surrounded by edema. The intestine wall where the parasite attached was damaged, with the villi epithelium and lamina propria in the mucosa being destroyed. The genomic DNA was isolated from all M. hirudinaceus samples, and PCR amplified the 489bp gene fragments were sequenced and confirmed that all 21 sequences were M. hirudinaceus. The haplotype analysis of the sequences revealed the presence of a central star-shaped haplotype, in addition to four other haplotypes. After conducting sequence analysis, the genetic differences between the M. hirudinaceus sequences obtained in this study and those reported from Europe and Japan suggest that this parasite is endemic to Türkiye's local wild boar population. Also, four haplotypes were identified, distinguishing it from other haplotypes by 1-5 mutation steps. It is essential to consider the worm's sequences and the formation of haplotypes, since these intrinsic characteristics may impact in the epidemiology and pathology of the worm in the future.

Bringing population ecology back to wild bees

AbstractIn recent years, motivated by widespread declines in wild bees, ecologists have prioritized learning about patterns of wild bee communities across the landscape at the expense of learning about the population‐level mechanisms driving those patterns. In this essay, we seek to revitalize the tradition of studying wild bee populations in a way that both contributes key knowledge for bee conservation and builds a strong conceptual understanding of the processes underpinning bee populations. We address two widespread concerns about investing in population‐level research. First, that population‐level studies are too conceptually narrow to provide broad inference. If population‐level studies are couched in general ecological theory, then findings from a single species can be generalized to many. We highlight how wild bees would make excellent candidates for exploring five areas of general ideas in population ecology, including nutritional ecology, drivers of vital rates, phenology and voltinism, habitat selection, and movement. Second, we address the concern that methods for studying bees at the population level are too difficult to implement. Methods for conducting population‐level studies of bees—specifically, identifying living bees in the field and studying individuals throughout their life cycles—are feasible to implement at the scales appropriate for answering population‐level questions, for example, a few species at a few sites. To facilitate adoption of these ideas, we developed an online field guide (www.watchingbees.com) and a detailed methods manual. More generally, we emphasize the value of linking data‐rich pattern‐oriented approaches in ecology with an understanding of the basic biology and mechanisms that generate those patterns.

Validation of an eDNA‐based workflow for monitoring inter‐ and intra‐specific CytB haplotype diversity of alpine amphibians

AbstractEnvironmental DNA (eDNA) analysis is a promising tool for monitoring wild animal populations and, more recently, their genetic variability. In this study, we used the mitochondrial Cytochrome B gene to develop and apply new eDNA metabarcoding assays targeting amphibian families and genera in order to estimate both inter‐ and intraspecific genetic diversity. We designed and tested seven new primer pairs (a) in silico against an amphibian reference database based on the target genera; (b) in vitro on tissue samples of the target species; and (c) in situ on water samples from 38 wetlands in the Province of Trento (Italy). Overall, most target species were amplified successfully, although some markers also amplified non‐target amphibian species. In addition, to complete the workflow, we compared the performance of three different bioinformatic pipelines (namely, MICCA with VSEARCH, and OBITools using ecotag or metabinkit), in retrieving reads and exact sequence variants from the metabarcoding datasets. Overall, the MICCA based pipeline retrieved more reads, but less putative haplotypes of amphibians. After comparing these sequences with previously known haplotypes from tissue‐based studies, when the aim is to both decrease the probability of detecting false haplotypes and retrieve the highest number of reads, we suggest using MICCA+VSEARCH, unless a direct comparison with tissue‐based genetic data is possible.

A non-invasive measure of bone growth in mammals: Validating urinary CTX-I as a bone resorption marker through long-bone growth velocity in bonobos.

Assessing bone growth trajectories in mammals is crucial for understanding life history dynamics, but the quantification of bone growth in natural settings can be challenging. Bone resorption markers that can be measured in urine, such as C-telopeptide of type I collagen (CTX-I), offer a non-invasive solution to assess bone growth. Although measurement of urinary CTX-I levels has been applied extensively in human studies, its use in other species is so far limited to a few clinical studies. To validate urinary CTX-I as a bone resorption marker under less controlled conditions, we investigated within-individual day-to-day variation, diurnal patterns, and sex and age-specific variation in zoo-housed bonobos (Pan paniscus). We then also correlated urinary CTX-I levels with forearm growth velocity measures. We found a day-to-day variability in urinary CTX-I levels of around 25%, comparable to human variation. Diurnally, CTX-I levels decreased, aligning with observations in humans and other species. Both sexes showed an age-related decline in urinary CTX-I levels, with a steady decrease after the age of 10 years. Additionally, we found a positive correlation between forearm growth velocity and urinary CTX-I levels across age in female, but not in male, bonobos. Our results demonstrate that urinary CTX-I levels are a meaningful measure of bone growth and highlight its potential to examine bone growth trajectories also in wild populations to investigate life history dynamics.

Torque Teno Sus Virus 1: A Potential Surrogate Pathogen to Study Pig-Transmitted Transboundary Animal Diseases.

Understanding the epidemiology and transmission dynamics of transboundary animal diseases (TADs) among wild pigs (Sus scrofa) will aid in preventing the introduction or containment of TADs among wild populations. Given the challenges associated with studying TADs in free-ranging populations, a surrogate pathogen system may predict how pathogens may circulate and be maintained within wild free-ranging swine populations, how they may spill over into domestic populations, and how management actions may impact transmission. We assessed the suitability of Torque teno sus virus 1 (TTSuV1) to serve as a surrogate pathogen for molecular epidemiological studies in wild pigs by investigating the prevalence, persistence, correlation with host health status and genetic variability at two study areas: Archbold's Buck Island Ranch in Florida and Savannah River Site in South Carolina. We then conducted a molecular epidemiological case study within Archbold's Buck Island Ranch site to determine how analysis of this pathogen could inform transmission dynamics of a directly transmitted virus. Prevalence was high in both study areas (40%, n = 190), and phylogenetic analyses revealed high levels of genetic variability within and between study areas. Our case study showed that pairwise host relatedness and geographic distance were highly correlated to pairwise viral genetic similarity. Molecular epidemiological analyses revealed a distinct pattern of direct transmission from pig to pig occurring within and between family groups. Our results suggest that TTSuV1 is highly suitable for molecular epidemiological analyses and will be useful for future studies of transmission dynamics in wild free-ranging pigs.

The bioefficacy of a novel VECTRON™ T500 indoor residual spray formulation in an experimental huts trial against Anopheles gambiae s.l. populations

Background: The emergence of insecticide resistance and its spread through populations of malaria vectors has decreased the number of insecticides available for control. Insecticide resistance has been observed in vector populations across sub-Saharan Africa in malaria endemic areas. Therefore, new compounds with different modes of action are needed that can be used in the management of resistance. The current study assessed the bioefficacy of the new indoor residual spray formulation, VECTRON™ T500 against Klypson 500 WG and water against laboratory reared and wild populations of Anopheles gambiae s.l.. The comparative experimental hut trial was implemented between June 2022 and December 2022 to determine the efficacy of VECTRON™ T500, containing the active ingredient (ai) broflanilide as a 50 % wettable powder (WP). The efficacy of VECTRON™ T500 was compared with a positive control, Klypson 500 WG, a wettable granule (WG) formulation that contains 50 % clothianidin. Cement and mud walls were sprayed with VECTRON™ T500, Klypson 500 WG with water sprayed as a negative control. The two insecticides and negative control were evaluated monthly for six months against laboratory and the field-derived An. gambiae s.l. using the standard WHO cone bioassays. Each wall had two cones on each day of testing. VECTRON™ T500 was sprayed on both surface types at a rate of 100mg ai/m2 whilst Klypson 500 WG was applied at a rate of 300 mg ai/m2. For both wall surface types, the vector from the laboratory-reared and the wild populations exhibited a low knockdown effect to both VECTRON™ T500 and Klypson 500 WG. A total of 3,840 mosquitoes were used of which 2,880 (75 %) were susceptible colony of An. gambiae s.s. and 960 (25 %) were wild An. gambiae s.l.. The VECTRON™ T500 induced a mortality of 97.8 %-98.1 % in the laboratory population and 83.2-95.0 % wild population mosquitoes on cement and mud-walled huts respectively while Klypson 500 WG ranged from 89.6-99.0 % for wild and 99.0-99.3 % for the laboratory population mosquitoes on cement and mud walls respectively. The knockdown due to VECTRON™ T500 was 7.08 % in the sixth month, while for Klypson 500 WG was 16.04-17.50 %. The monthly wall cone bioassay mortality with VECTRON™ T500 remained over 80 % for 6 months post-spraying for both laboratory and wild populations. The findings of this study have shown VECTRON™ T500 to have extended efficacy against malaria vector mosquitoes when applied to cement and mud walls. The evaluated new IRS formulation, VECTRON™ T500, performed equally with the positive control, Klypson 500 WG, regarding its impact on vector mortality.

First report of Oreochromis niloticus in the Sonora River, Mexico

Commercial farming of tilapia species has been spread to many countries worldwide to meet the need for animal protein at an affordable price, which has led tilapias to invade natural areas. Consequently, tilapias have established wild populations, causing a great negative impact on native biodiversity. The Sonora River, located in northwest Mexico, has an approximate length of 400 km, and at least four native fish species inhabit it. Nevertheless, the Sonora River has been severely reduced and contaminated by open-pit mining. According to existing knowledge, the presence of tilapias is not reported in the Sonora River; hence, the present study is the first report of the presence of the Nile tilapia Oreochromis niloticus in a site near the town of Baviácora, Sonora, Mexico. The presence of this invasive species may represent a severe threat to the biotic component of this ecosystem, which is already affected by mining pollution.