Predicting functional responses in agro-ecosystems from animal movement data to improve management of invasive pests

Functional responses describe how changing resource availability affects con- sumer resource use, thus providing a mechanistic approach to prediction of the invasibility and potential damage of invasive alien species (IAS). However, functional responses can be context dependent, varying with resource characteristics and availability, consumer attributes, and environmental variables. Identifying context dependencies can allow invasion and damage risk to be predicted across different ecoregions. Understanding how ecological factors shape the functional response in agro-ecosystems can improve predictions of hotspots of highest impact and inform strategies to mitigate damage across locations with varying crop types and avail- ability. We linked heterogeneous movement data across different agro-ecosystems to predict ecologically driven variability in the functional responses. We applied our approach to wild pigs (Sus scrofa), one of the most successful and detrimental IAS worldwide where agricultural resource depredation is an important driver of spread and establishment. We used continental- scale movement data within agro-ecosystems to quantify the functional response of agricul- tural resources relative to availability of crops and natural forage. We hypothesized that wild pigs would selectively use crops more often when natural forage resources were low. We also examined how individual attributes such as sex, crop type, and resource stimulus such as dis- tance to crops altered the magnitude of the functional response. There was a strong agricul- tural functional response where crop use was an accelerating function of crop availability at low density (Type III) and was highly context dependent. As hypothesized, there was a reduced response of crop use with increasing crop availability when non-agricultural resources were more available, emphasizing that crop damage levels are likely to be highly heterogeneous depending on surrounding natural resources and temporal availability of crops. We found sig- nificant effects of crop type and sex, with males spending 20% more time and visiting crops 58% more often than females, and both sexes showing different functional responses depend- ing on crop type. Our application demonstrates how commonly collected animal movement data can be used to understand context dependencies in resource use to improve our under- standing of pest foraging behavior, with implications for prioritizing spatiotemporal hotspots of potential economic loss in agro-ecosystems

Investigating Pseudorabies Virus as a Mortality Factor for California Mountain Lions

Wild pigs in North America carry multiple pathogens capable of causing diseases in wildlife, people, and domestic animals. Wild pigs are the reservoir host of pseudorabies virus (PrV) which is a fatal infection in wild carnivores. We previously conducted surveillance for PrV in wild pigs from Kern County, California where the distribution of wild pigs overlaps with native mountain lion. We found that 100% of wild pigs were exposed to PrV, and 6% were shedding the virus. Black bears and pumas have been observed preying on wild pigs in the region suggesting that they are vulnerable to exposure to PrV from pigs. We conducted retrospective, post-mortem surveillance for PrV on 16 pumas from five counties in south central California. None of the pumas tested positive for PrV. In Florida, PrV is attributed to one-third of the deaths in Florida panthers. Wild pigs are a large portion of the diet of panthers in Florida, but studies in California suggest pigs may not be utilized as frequently. This difference in diet could account for the lack of evidence that PrV causes measurable mortality in California pumas. Nonetheless, in management areas with carnivores, wild pig management should be carefully considered

Investigating Pseudorabies Virus as a Mortality Factor for California Mountain Lions

Wild pigs in North America carry multiple pathogens capable of causing diseases in wildlife, people, and domestic animals. Wild pigs are the reservoir host of pseudorabies virus (PrV) which is a fatal infection in wild carnivores. We previously conducted surveillance for PrV in wild pigs from Kern County, California where the distribution of wild pigs overlaps with native mountain lion. We found that 100% of wild pigs were exposed to PrV, and 6% were shedding the virus. Black bears and pumas have been observed preying on wild pigs in the region suggesting that they are vulnerable to exposure to PrV from pigs. We conducted retrospective, post-mortem surveillance for PrV on 16 pumas from five counties in south central California. None of the pumas tested positive for PrV. In Florida, PrV is attributed to one-third of the deaths in Florida panthers. Wild pigs are a large portion of the diet of panthers in Florida, but studies in California suggest pigs may not be utilized as frequently. This difference in diet could account for the lack of evidence that PrV causes measurable mortality in California pumas. Nonetheless, in management areas with carnivores, wild pig management should be carefully considered

Genetic Diversity and Structure of the Fisher (Martes Pennanti) in a Peninsular and Peripheral Metapopulation

Evolutionary processes can be strongly affected by landscape features. In vagile carnivores that disperse widely, however, genetic structure has been found to be minimal. Using microsatellite DNA primers developed for other mustelids, we found that populations of a vagile forest carnivore, the fisher (Martes pennanti), exhibit high genetic structure (FST = 0.45, SE = 0.07) and limited gene flow (Nm \u3c 1) within a .1,600-km narrow strip of forested habitat; that genetic diversity decreases from core to periphery; and that populations do not show an equilibrium pattern of isolation-by-distance. Genetic structure was greater at the periphery than at the core of the distribution and our data fit a 1-dimensional model of stepping-stone range expansion. Multiple lines of paleontological and genetic evidence suggest that the fisher recently (\u3c5,000 years ago) expanded into the mountain forests of the Pacific coast. The reduced dimensionality of the distribution of the fisher in western coastal forests appears to have contributed to the high levels of structure and decreasing diversity from north to south. These effects were likely exacerbated by human-caused changes to the environment. The low genetic diversity and high genetic structure of populations in the southern Sierra Nevada suggest that populations in this part of the geographic range are vulnerable to extinction

Predicting functional responses in agro-ecosystems from animal movement data to improve management of invasive pests

Functional responses describe how changing resource availability affects con- sumer resource use, thus providing a mechanistic approach to prediction of the invasibility and potential damage of invasive alien species (IAS). However, functional responses can be context dependent, varying with resource characteristics and availability, consumer attributes, and environmental variables. Identifying context dependencies can allow invasion and damage risk to be predicted across different ecoregions. Understanding how ecological factors shape the functional response in agro-ecosystems can improve predictions of hotspots of highest impact and inform strategies to mitigate damage across locations with varying crop types and avail- ability. We linked heterogeneous movement data across different agro-ecosystems to predict ecologically driven variability in the functional responses. We applied our approach to wild pigs (Sus scrofa), one of the most successful and detrimental IAS worldwide where agricultural resource depredation is an important driver of spread and establishment. We used continental- scale movement data within agro-ecosystems to quantify the functional response of agricul- tural resources relative to availability of crops and natural forage. We hypothesized that wild pigs would selectively use crops more often when natural forage resources were low. We also examined how individual attributes such as sex, crop type, and resource stimulus such as dis- tance to crops altered the magnitude of the functional response. There was a strong agricul- tural functional response where crop use was an accelerating function of crop availability at low density (Type III) and was highly context dependent. As hypothesized, there was a reduced response of crop use with increasing crop availability when non-agricultural resources were more available, emphasizing that crop damage levels are likely to be highly heterogeneous depending on surrounding natural resources and temporal availability of crops. We found sig- nificant effects of crop type and sex, with males spending 20% more time and visiting crops 58% more often than females, and both sexes showing different functional responses depend- ing on crop type. Our application demonstrates how commonly collected animal movement data can be used to understand context dependencies in resource use to improve our under- standing of pest foraging behavior, with implications for prioritizing spatiotemporal hotspots of potential economic loss in agro-ecosystems

Trypanosoma cruzi infection in mammals in Florida: New insight into the transmission of T. cruzi in the southeastern United States

In Latin America, synanthropic mammalian reservoirs maintain Trypanosoma cruzi, a parasitic protozoan, where they facilitate the transmission of the parasite to humans and other reservoir hosts in peridomestic settings. In the United States, raccoons (Procyon lotor) and Virginia opossums (Didelphis virginiana) are known synanthropic T. cruzi reservoir hosts; however, the role these species have in the peridomestic transmission cycle in the US is not well understood. This study aimed to identify the suite of mammalian reservoirs of T. cruzi in Florida. We also compared infection prevalence in raccoon populations sampled from within and outside of the estimated distribution of the common T. cruzi vector in Florida to gain insight into how the arthropod vector distribution impacts the distribution of infected reservoirs in the state. Finally, to investigate the impact of peridomestic landscapes on parasite prevalence, we compared the prevalence of T. cruzi-infected raccoons and opossums across five paired peridomestic and sylvatic sites. We live-trapped and collected peripheral blood samples from 135 raccoons, 112 opossums, 18 nine-banded armadillos (Dasypus novemcinctus), and nine species of rodents in north central Florida. Using quantitative PCR methods, we found that raccoons (42.2%, 95% CI [34.2–50.7%]) and opossums (50.9%, 95% CI [41.8–60.0%]) were infected with T. cruzi and the prevalence across habitats was similar for both raccoons (peridomestic: n = 77, 44.2%, 95% CI [33.6–55.3%], sylvatic: n = 58, 39.7%, 95% CI [28.1–52.5%]) and opossums (peridomestic: n = 66, 48.5%, 95% CI [36.8–60.3%], sylvatic: n = 46, 54.3%, 95% CI [40.2–67.8%]). Raccoons sampled outside the estimated distribution of Triatoma sanguisuga were not infected with T. cruzi (n = 73, 0.0%, 95% CI [0.0–5.0%]). Our study did not indicate that peridomestic habitats in Florida maintained a higher infection prevalence than their sylvatic counterparts; however, we did find a difference in prevalence within vs. outside the estimated vector distribution in Florida

Using DNA Metabarcoding to Examine Wild Pig (Sus scrofa) Diets in a Subtropical Agro-Ecosystem

The wild pig is well known for its generalist diet, a contributing factor to its successful invasion around the globe. We used DNA metabarcoding analyses of scat to examine wild pig diet on a cow-calf operation in south-central Florida. This 4,249-ha ranch is comprised of improved pastures and semi-native pastures that contain a mosaic of vegetation types. Both pasture types contain numerous wetlands and ditches as well as oak-palm woodlands. Fecal sampling was conducted along transects from March 2016 to February 2017. The study site was divided into five sampling areas to ensure dispersed sampling across the ranch. At least five freshly deposited scats were collected every two months from each sampling area and frozen. Regions of multiple genes that targeted either animal or plant DNA (CO1, trnL, and 12S rRNA marker genes) were selected for high throughput sequencing. Sequences were identified using the GenBank reference database. Two hundred nineteen fecal samples were collected and 196 were analyzed. Consensus lineages were retained if they could be confidently identified to family and were likely intentionally consumed by a pig. Between the three marker genes, 66 plant, 68 animal, and 12 fungal families were identified. Plant species dominated the diet with oak, torpedograss, joyweed, Bahiagrass, dayflower, and other grasses occurring in over half the samples analyzed. Animals were present across a wide taxonomic breadth, but encountered less frequently than plants with the exception of an exotic earthworm. Cattle, house mouse, cotton mouse, raccoon, mole cricket, Virginia opossum, and six species of fly were recorded from over 10% of fecal samples. This represents the first study to employ DNA metabarcoding to examine the dietary composition of this invasive vertebrate across an entire year

Integrated pest management strategies targeting the Florida kissing bug, Triatoma sanguisuga: Preventing this vector of Chagas disease from invading your home

Triatomines (Hemiptera: Reduviidae: Triatominae), commonly called “kissing bugs”, are blood-sucking pests and vectors of the protozoan parasite Trypanosoma cruzi, the causative agent of Chagas disease (CD). Eleven species of kissing bugs occur throughout the southern half of the USA, four of which are well known to invade human dwellings. Certain kissing bugs in the USA are known to transmit T. cruzi to humans and other animals and their bites can also lead to serious allergic reactions, including anaphylaxis. In Florida, the kissing bug Triatoma sanguisuga frequently invades homes, bites residents, and has been found infected with T. cruzi, placing humans and companion animals at risk for CD. This review outlines integrated pest management (IPM) strategies for minimizing human exposure to T. sanguisuga and CD. A comprehensive IPM plan for kissing bugs includes detailed inspections, removal of vertebrate host nesting areas, and kissing bug harborage, home improvements to exclude kissing bugs from entering structures, pest removal, and judicious use of pesticides. This approach can limit or eliminate kissing bug entry into residential structures, thereby preventing kissing bug bites, and CD infections in humans and companion animals

Quantifying drivers of wild pig movement across multiple spatial and temporal scales

Background: The movement behavior of an animal is determined by extrinsic and intrinsic factors that operate at multiple spatio-temporal scales, yet much of our knowledge of animal movement comes from studies that examine only one or two scales concurrently. Understanding the drivers of animal movement across multiple scales is crucial for understanding the fundamentals of movement ecology, predicting changes in distribution, describing disease dynamics, and identifying efficient methods of wildlife conservation and management. Methods: We obtained over 400,000 GPS locations of wild pigs from 13 different studies spanning six states in southern U.S.A., and quantified movement rates and home range size within a single analytical framework. We used a generalized additive mixed model framework to quantify the effects of five broad predictor categories on movement: individual-level attributes, geographic factors, landscape attributes, meteorological conditions, and temporal variables. We examined effects of predictors across three temporal scales: daily, monthly, and using all data during the study period. We considered both local environmental factors such as daily weather data and distance to various resources on the landscape, as well as factors acting at a broader spatial scale such as ecoregion and season. Results: We found meteorological variables (temperature and pressure), landscape features (distance to water sources), a broad-scale geographic factor (ecoregion), and individual-level characteristics (sex-age class), drove wild pig movement across all scales, but both the magnitude and shape of covariate relationships to movement differed across temporal scales. Conclusions: The analytical framework we present can be used to assess movement patterns arising from multiple data sources for a range of species while accounting for spatio-temporal correlations. Our analyses show the magnitude by which reaction norms can change based on the temporal scale of response data, illustrating the importance of appropriately defining temporal scales of both the movement response and covariates depending on the intended implications of research (e.g., predicting effects of movement due to climate change versus planning local-scale management). We argue that consideration of multiple spatial scales within the same framework (rather than comparing across separate studies post-hoc) gives a more accurate quantification of cross-scale spatial effects by appropriately accounting for error correlation