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Natural antibodies are used to compare immune systems across taxa, to study wildlife disease ecology, and as selection markers in livestock breeding. These immunoglobulins are present prior to immune stimulation. They are described as having low antigen specificity or polyreactive binding and are measured by binding to self-antigens or novel exogenous proteins. Most studies use only one or two antigens to measure natural antibodies and ignore potential effects of antigen specificity in analyses. It remains unclear how different antigen-specific natural antibodies are related or how diversity among natural antibodies may affect analyses of these immunoglobulins. Using genetically distinct lines of chickens as a model system, we tested the hypotheses that (1) antigen-specific natural antibodies are independent of each other and (2) antigen specificity affects the comparison of natural antibodies among animals. We used blood cell agglutination and enzyme-linked immunosorbent assays to measure levels of natural antibodies binding to four antigens: (i) rabbit erythrocytes, (ii) keyhole limpet hemocyanin, (iii) phytohemagglutinin, or (iv) ovalbumin. We observed that levels of antigen specific natural antibodies were not correlated. There were significant differences in levels of natural antibodies among lines of chickens, indicating genetic variation for natural antibody production. However, line distinctions were not consistent among antigen specific natural antibodies. These data show that natural antibodies are a pool of relatively distinct immunoglobulins, and that antigen specificity may affect interpretation of natural antibody function and comparative immunology.
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Galinhas , Animais , Galinhas/imunologia , Coelhos , Antígenos/imunologia , Eritrócitos/imunologia , Especificidade de Anticorpos/imunologia , Ovalbumina/imunologia , Anticorpos/imunologia , Hemocianinas/imunologia , Fito-Hemaglutininas/imunologia , Ensaio de Imunoadsorção EnzimáticaRESUMO
Chewing lice infesting avian hosts can significantly affect host health and fitness. Here, we present quantitative data on host body condition and louse abundance observed from 121 Rough-legged Hawks (Buteo lagopus) sampled across the North American nonbreeding range. Among hawks examined, louse prevalence was 71%, with a mean abundance and intensity of 9.1 and 12.8 lice, respectively. We identified lice as Craspedorrhynchus sp., either Craspedorrhynchus dilatatus or Craspedorrhynchus taurocephalus, dependent on future taxonomic revision of the genus. Female and juvenile hawks had greater louse intensity and prevalence compared with male and adult hawks, respectively. Host body condition, measured as a breast muscle score (keel score), was negatively correlated with louse abundance after controlling for host age and sex. Possible explanations for these patterns include the following: sex-biased louse transfer between adults and nestlings, when female nestlings experience increased transfer loads; body size differences between males and females, when females are larger than males in each life stage; and preening limitations in females and juveniles, when both spend more time hunting and less time preening relative to adult males. Our results corroborate previous studies suggesting that the primary sources of intraspecific variation in louse abundance are host body size and preening limitations.
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Selection of livestock for disease resistance is challenging due to the difficulty in obtaining reliable phenotypes. Antibodies are immunological molecules that provide direct and indirect defenses against infection and link the activities of both the innate and adaptive compartments of the immune system. As a result, antibodies have been used as a trait in selection for immune defense. The goal of this study was to identify genomic regions associated with natural and induced antibodies in chickens using low-pass sequencing. Enzyme-linked immunosorbent assays were used to quantify innate (natural) antibodies binding KLH, OVA, and PHA and induced (adaptive) antibodies binding IBD, IBV, NDV, and REO. We collected plasma from four White Leghorn (WL), two White Plymouth Rock (WPR), and two Rhode Island Red (RIR) lines. Samples numbers ranged between 198 and 785 per breed. GWAS was performed within breed on data pre-adjusted for Line-Hatch-Sex effects using GCTA. A threshold of p = 10-6 was used to select genes for downstream annotation and enrichment analysis with SNPEff and Panther. Significant enrichment was found for the defense/immunity protein, immunoglobulin receptor superfamily, and the antimicrobial response protein in RIR; and the immunoglobulin receptor superfamily, defense/immunity protein, and protein modifying enzyme in WL. However, none were present in WPR, but some of the selected SNP were annotated in immune pathways. This study provides new insights regarding the genetics of the antibody response in layer chickens.
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Agricultural simplification continues to expand at the expense of more diverse forms of agriculture. This simplification, for example, in the form of intensively managed monocultures, poses a risk to keeping the world within safe and just Earth system boundaries. Here, we estimated how agricultural diversification simultaneously affects social and environmental outcomes. Drawing from 24 studies in 11 countries across 2655 farms, we show how five diversification strategies focusing on livestock, crops, soils, noncrop plantings, and water conservation benefit social (e.g., human well-being, yields, and food security) and environmental (e.g., biodiversity, ecosystem services, and reduced environmental externalities) outcomes. We found that applying multiple diversification strategies creates more positive outcomes than individual management strategies alone. To realize these benefits, well-designed policies are needed to incentivize the adoption of multiple diversification strategies in unison.
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Agricultura , Biodiversidade , Conservação dos Recursos Naturais , Ecossistema , Humanos , Fazendas , SoloRESUMO
BACKGROUND: Water quality is known to influence the development and survival of larval mosquitoes, which affects mosquito-borne pathogen transmission as a function of the number of mosquitoes that reach adulthood and blood feed. Although water properties are known to affect mosquito development, few studies have investigated the link among soil properties, water quality, and mosquito development. Given the large number of ground-breeding mosquito species, this linkage is a potentially important factor to consider in mosquito ecology. In this study, we explored the effects of different soils on multiple life history parameters of the ground-breeding mosquito species Culex quinquefasciatus (Diptera: Culicidae). METHODS: Cx. quinquefasciatus larvae were reared in water combined with different soil substrates (sandy, silt, or clay loam textures) at increasing soil to water volume ratios, with and without the addition of organic matter (fish food). Gravid mosquitoes were offered different soil-water extracts to investigate soil effects on oviposition preference. RESULTS: Without the addition of organic matter, larval survival and development differed significantly among waters with different soil textures and volumes of substrate. Mosquitoes in water with clay loam soil survived longer and developed further than mosquitoes in other soil waters. Larvae survived for longer periods of time with increased volumes of soil substrate. Adding organic matter reduced the differences in larval survival time, development, and pupation among soil-water extracts. Adult female mosquitoes oviposited more frequently in water with clay loam soil, but the addition of organic matter reduced the soil effects on oviposition preference. CONCLUSIONS: This study suggests soil composition affects larval mosquito survival and development, as well as the oviposition preference of gravid females. Future studies could differentiate abiotic and biotic soil features that affect mosquitoes and incorporate soil variation at the landscape scale into models to predict mosquito population dynamics and mosquito-borne pathogen transmission.
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Culex , Culicidae , Feminino , Animais , Oviposição , Solo , Argila , LarvaRESUMO
Diet composition modulates animals' ability to resist parasites and recover from stress. Broader diet breadths enable omnivores to mount dynamic responses to parasite attack, but little is known about how plant/prey mixing might influence responses to infection. Using omnivorous deer mice (Peromyscus maniculatus) as a model, we examine how varying plant and prey concentrations in blended diets influence resistance and body condition following infestation by Rocky Mountain wood ticks (Dermacentor andersoni). In two repeated experiments, deer mice fed for 4 weeks on controlled diets that varied in proportions of seeds and insects were then challenged with 50 tick larvae in two sequential infestations. The numbers of ticks successfully feeding on mice declined by 25% and 66% after the first infestation (in the first and second experiments, respectively), reflecting a pattern of acquired resistance, and resistance was strongest when plant/prey ratios were more equally balanced in mouse diets, relative to seed-dominated diets. Diet also dramatically impacted the capacity of mice to cope with tick infestations. Mice fed insect-rich diets lost 15% of their body weight when parasitized by ticks, while mice fed seed-rich diets lost no weight at all. While mounting/maintaining an immune response may be energetically demanding, mice may compensate for parasitism with fat and carbohydrate-rich diets. Altogether, these results suggest that a diverse nutritional landscape may be key in enabling omnivores' resistance and resilience to infection and immune stressors in their environments.
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Parasitos , Doenças dos Roedores , Infestações por Carrapato , Animais , Peromyscus , Larva/fisiologia , Infestações por Carrapato/parasitologia , Infestações por Carrapato/veterinária , Dieta/veterináriaRESUMO
Foodborne pathogens cause over 9 million illnesses in the United States each year, and Campylobacter from chickens is the largest contributor. Rearing poultry outdoors without the use of antibiotics is becoming an increasingly popular style of farming; however, little is understood about how environmental factors and farm management alter pathogen prevalence. Our survey of 27 farms in California, Oregon, Washington, and Idaho, USA, revealed a diversity of management practices used to rear poultry in the open environment. Here, we assess environmental and management factors that impact Campylobacter spp. prevalence in 962 individual chicken fecal samples from 62 flocks over a three-year period. We detected Campylobacter spp. in 250/962 (26.0%) of fecal samples screened, in 69.4% (43/62) of flocks, and on 85.2% (23/27) of farms. We found that Campylobacter spp. prevalence was predicted to increase in poultry on farms with higher average wind speeds in the seven days preceding sampling; on farms embedded in more agricultural landscapes; and in flocks typified by younger birds, more rotations, higher flock densities, and the production of broilers. Collectively, our results suggest that farms in areas with higher wind speeds and more surrounding agriculture face greater risk of Campylobacter spp. introduction into their flocks.
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Open-environment poultry farms that allow chickens to forage outdoors are becoming increasingly common throughout the United States and Europe; however, there is little information regarding the diversity and prevalence of ectoparasites in these farming systems. Eight to 25 birds were captured and surveyed for ectoparasites on each of 17 farms across the states of Washington, Idaho, Oregon, and California. Among the farms sampled, six louse species (Phthiraptera: Ischnocera & Amblycera) and two parasitic mite species (Acari: Mesostigmata) were collected and identified: Goniodes gigas (Taschenberg, 1879; Phthiraptera: Menoponidae) on one farm, Menacathus cornutus (Schömmer, 1913; Phthiraptera: Menoponidae) on one farm, Menopon gallinae (Linnaeus, 1758; Phthiraptera: Menoponidae) on six farms, Lipeurus caponis (Linnaeus, 1758; Phthiraptera: Philopteridae) on five farms, Menacanthus stramineus (Nitzsch, 1818; Phthiraptera: Menoponidae) on nine farms, Goniocotes gallinae De Geer (Phthiraptera: Philopteridae) on 11 farms, Dermanyssus gallinae (De Geer, 1778; Mesostigmata: Dermanyssidae) on two farms, and Ornithonyssus sylviarum (Canestrini & Fanzago, 1877; Mesostigmata: Macronyssidae) on one farm. The diversity of ectoparasites on these open environment poultry farms highlights a need for additional research on ectoparasite prevalence and intensity in these poultry farming systems.
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Iscnóceros , Ácaros , Ftirápteros , Doenças das Aves Domésticas , Animais , Galinhas/parasitologia , Fazendas , Idaho/epidemiologia , Oregon , Aves Domésticas , Doenças das Aves Domésticas/epidemiologia , Doenças das Aves Domésticas/parasitologia , Prevalência , WashingtonRESUMO
Growing demand for poultry meat and eggs labeled as organic, cage free, or pasture raised has increased the number of producers that manage chickens outdoors. In these open environments, there are likely diverse enteric parasites sustained by fecal-oral transmission or passage through intermediate invertebrate hosts (e.g., worms and insects) that chickens consume. Enteric parasites can reduce chicken health and productivity, but there are few published data describing the identities or prevalence of these parasites on farms that use open environments in the United States. We surveyed 27 poultry farms with open environments that were situated across a wide geographic range, including California, Oregon, Idaho, and Washington. These farms did not use anticoccidial drugs, coccidia vaccines, or parasiticides. Flock size, enclosure area, flock density, flock rotation frequency, and average flock age were highly correlated for all the farms in this study. We analyzed how enclosure size and flock rotations per year (which represented two axes of variation in management) correlated with prevalence of five observed parasite taxa at the farm level. Across all flocks, we detected by fecal flotation Eimeria spp. (95% flocks), Ascaridia galli (69%), Heterakis gallinarum (52%), Capillaria spp. (39%), Strongyloides avium (13%), tapeworm species (29%), Cryptosporidium spp. (3%), and Dispharynx nasuta (1%). Eighty-five percent of samples were coinfected with two or more parasite taxa. Sixty-seven percent of farms raised only layer chicken breeds, 4% raised only broiler breeds, and 30% raised both layer and broiler breeds. The average age of the broiler flocks was 11.0 wk (±1.1 SE), and flocks were moved 54.7 (±17.9) times annually to new locations in pastures (hereafter, "rotation"). Layer flocks averaged 84.9 (±7.67) wk of age and were moved less often on farms being rotated 20.0 (±6.05) times per year. Generalized linear mixed models indicated that for every 1 m2 increase in enclosure size, the odds of detecting Eimeria spp. increased by 0.03%. Furthermore, for every additional rotation per year, the odds of detecting A. galli decreased by 1.3%. For every additional rotation per year, the odds of detecting tapeworm species increased by 2.2%. We found no evidence that flock spatial management affected prevalence of the other parasites observed on the farms. Farming practices and parasite responses in these systems are highly varied, which makes it difficult to identify potential management interventions for reducing these infections.
Patrones de prevalencia de parásitos entéricos de pollos manejados en ambientes abiertos en el oeste de los Estados Unidos. La creciente demanda de carne de pollo y huevos etiquetados como orgánicos, sin jaula o criados en pastoreo ha aumentado el número de productores que manejan pollos al aire libre. En estos entornos abiertos, es probable que existan diversos parásitos entéricos que permanecen debido a la transmisión fecal-oral o por su paso a través de huéspedes invertebrados intermedios (por ejemplo, gusanos e insectos) que son consumidos por los pollos. Los parásitos entéricos pueden reducir la salud y la productividad de los pollos, pero existe poca información publicada que describa las identidades o la prevalencia de estos parásitos en granjas que utilizan entornos abiertos en los Estados Unidos. Se realizó una encuesta incluyendo 27 granjas avícolas con entornos abiertos que estaban situadas en un amplio rango geográfico, incluyendo California, Oregón, Idaho y Washington. Estas granjas no usaban medicamentos anticoccidiales, vacunas contra coccidias ni parasiticidas. El tamaño de la parvada, el área de pastoreo, la densidad de la parvada, la frecuencia de rotación de la parvada y la edad promedio de la parvada estuvieron altamente correlacionados para todas las granjas en este estudio. Se analizó cómo el tamaño del recinto y las rotaciones de parvadas por año (que representaban dos ejes de variación en el manejo) se correlacionaban con la prevalencia de cinco taxones de parásitos observados a nivel de granja. En todas las parvadas, se detectó por flotación fecal Eimeria spp. (95% de las parvadas), Ascaridia galli (69%), Heterakis gallinarum (52%), Capillaria spp. (39%), Strongyloides avium (13%), especies de nemátodos planos (29%), Cryptosporidium spp. (3%) y Dispharynx nasuta (1%). El ochenta y cinco por ciento de las muestras estaban coinfectadas con dos o más taxones de parásitos. El sesenta y siete por ciento de las granjas criaban solo razas de gallinas de postura, el 4% solo criaban razas de pollos de engorde y el 30% criaban razas de gallinas de postura y de pollos de engorde. La edad promedio de las parvadas de pollos de engorde fue de 11.0 semanas (±1.1 SE) y las parvadas se trasladaron 54.7 (±17.9) veces al año a nuevas ubicaciones en los pastos (en adelante, "rotación"). Las parvadas ponedoras promediaron 84.9 (± 7.67) semanas de edad y se trasladaron con menos frecuencia en granjas que se rotaron 20.0 (± 6.05) veces al año. Los modelos lineales mixtos generalizados indicaron que por cada aumento de un metro cuadrado en el tamaño del área de pastoreo, las probabilidades de detectar Eimeria spp. se incrementaron en un 0.03%. Además, por cada rotación adicional por año, las probabilidades de detectar A. galli disminuyeron en un 1.3%. Por cada rotación adicional por año, las probabilidades de detectar especies de tenia aumentaron en un 2.2%. No encontramos evidencia de que el manejo del espacio de la parvada afectara la prevalencia de los otros parásitos observados en las granjas. Las prácticas agrícolas y las respuestas de los parásitos en estos sistemas son muy variadas, lo que dificulta la identificación de posibles intervenciones de manejo para reducir estas infecciones.
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Criptosporidiose , Cryptosporidium , Eimeria , Parasitos , Doenças das Aves Domésticas , Criação de Animais Domésticos , Animais , Galinhas , Doenças das Aves Domésticas/prevenção & controle , Prevalência , Estados Unidos/epidemiologiaRESUMO
Recent foodborne illness outbreaks have heightened pressures on growers to deter wildlife from farms, jeopardizing conservation efforts. However, it remains unclear which species, particularly birds, pose the greatest risk to food safety. Using >11,000 pathogen tests and 1565 bird surveys covering 139 bird species from across the western United States, we examined the importance of 11 traits in mediating wild bird risk to food safety. We tested whether traits associated with pathogen exposure (e.g., habitat associations, movement, and foraging strategy) and pace-of-life (clutch size and generation length) mediated foodborne pathogen prevalence and proclivities to enter farm fields and defecate on crops. Campylobacter spp. were the most prevalent enteric pathogen (8.0%), while Salmonella and Shiga-toxin producing Escherichia coli (STEC) were rare (0.46% and 0.22% prevalence, respectively). We found that several traits related to pathogen exposure predicted pathogen prevalence. Specifically, Campylobacter and STEC-associated virulence genes were more often detected in species associated with cattle feedlots and bird feeders, respectively. Campylobacter was also more prevalent in species that consumed plants and had longer generation lengths. We found that species associated with feedlots were more likely to enter fields and defecate on crops. Our results indicated that canopy-foraging insectivores were less likely to deposit foodborne pathogens on crops, suggesting growers may be able to promote pest-eating birds and birds of conservation concern (e.g., via nest boxes) without necessarily compromising food safety. As such, promoting insectivorous birds may represent a win-win-win for bird conservation, crop production, and food safety. Collectively, our results suggest that separating crop production from livestock farming may be the best way to lower food safety risks from birds. More broadly, our trait-based framework suggests a path forward for co-managing wildlife conservation and food safety risks in farmlands by providing a strategy for holistically evaluating the food safety risks of wild animals, including under-studied species.
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Animais Selvagens , Escherichia coli Shiga Toxigênica , Animais , Aves , Bovinos , Fazendas , Salmonella , Estados UnidosRESUMO
Engaging with socio-scientific issues often involves making sense of how - and for whom - actions, choices, and policies might affect aspects of daily life. Understanding the complexity of socio-scientific issues also requires recognizing the interconnectedness of - and working across - multiple communities and professions. We suggest that art, whether musical composition, illustrations, or sculpture / collage across materials would promote the synthesis of different types of knowledge across different scales and systems. The present investigation seeks to understand how arts integration into STEM curriculum could support systems thinking around socio-scientific issues, specifically around the issue of pathogen transmission in rural-agricultural communities. Our after-school program, which works with 3rd - 5th grade students in rural-agricultural communities, leverages the arts to promote systems-level understanding of zoonotic diseases and ecosystem dynamics. A total of 23 students across two sites located in rural communities in the Western United States participated in our afterschool program. We found that after completing the program students expanded their understanding of both the connections between concepts and an understanding of careers related to ecosystem dynamics. We suggest that educators can integrate both arts and sciences together to enhance systems thinking and expand student perception of the interconnectedness of STEM disciplines and their everyday lives.
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Interest is growing among out-of-school time (OST) educators in integrating the arts into STEM (science, technology, engineering, and mathematics) programming (e.g., Kelton & Saraniero, 2018). Arts-integrated STEM-or STEAM-programming now takes place in a wide variety of OST environments, from relatively institutional learning settings, such as a library, to emergent or fluid settings, such as a pop-up program in a housing development community room.
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Enteric illnesses remain the second largest source of communicable diseases worldwide, and wild birds are suspected sources for human infection. This has led to efforts to reduce pathogen spillover through deterrence of wildlife and removal of wildlife habitat, particularly within farming systems, which can compromise conservation efforts and the ecosystem services wild birds provide. Further, Salmonella spp. are a significant cause of avian mortality, leading to additional conservation concerns. Despite numerous studies of enteric bacteria in wild birds and policies to discourage birds from food systems, we lack a comprehensive understanding of wild bird involvement in transmission of enteric bacteria to humans. Here, we propose a framework for understanding spillover of enteric pathogens from wild birds to humans, which includes pathogen acquisition, reservoir competence and bacterial shedding, contact with people and food, and pathogen survival in the environment. We place the literature into this framework to identify important knowledge gaps. Second, we conduct a meta-analysis of prevalence data for three human enteric pathogens, Campylobacter spp., E. coli, and Salmonella spp., in 431 North American breeding bird species. Our literature review revealed that only 3% of studies addressed the complete system of pathogen transmission. In our meta-analysis, we found a Campylobacter spp. prevalence of 27% across wild birds, while prevalence estimates of pathogenic E. coli (20%) and Salmonella spp. (6.4%) were lower. There was significant bias in which bird species have been tested, with most studies focusing on a small number of taxa that are common near people (e.g. European starlings Sturnus vulgaris and rock pigeons Columba livia) or commonly in contact with human waste (e.g. gulls). No pathogen prevalence data were available for 65% of North American breeding bird species, including many commonly in contact with humans (e.g. black-billed magpie Pica hudsonia and great blue heron Ardea herodias), and our metadata suggest that some under-studied species, taxonomic groups, and guilds may represent equivalent or greater risk to human infection than heavily studied species. We conclude that current data do not provide sufficient information to determine the likelihood of enteric pathogen spillover from wild birds to humans and thus preclude management solutions. The primary focus in the literature on pathogen prevalence likely overestimates the probability of enteric pathogen spillover from wild birds to humans because a pathogen must survive long enough at an infectious dose and be a strain that is able to colonize humans to cause infection. We propose that future research should focus on the large number of under-studied species commonly in contact with people and food production and demonstrate shedding of bacterial strains pathogenic to humans into the environment where people may contact them. Finally, studies assessing the duration and intensity of bacterial shedding and survival of bacteria in the environment in bird faeces will help provide crucial missing information necessary to calculate spillover probability. Addressing these essential knowledge gaps will support policy to reduce enteric pathogen spillover to humans and enhance bird conservation efforts that are currently undermined by unsupported fears of pathogen spillover from wild birds.
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Infecções Bacterianas/veterinária , Doenças das Aves/transmissão , Migração Animal , Animais , Animais Selvagens , Infecções Bacterianas/epidemiologia , Infecções Bacterianas/microbiologia , Infecções Bacterianas/transmissão , Doenças das Aves/epidemiologia , Doenças das Aves/microbiologia , Aves , Reservatórios de Doenças/microbiologia , Reservatórios de Doenças/veterinária , Humanos , Gado , Prevalência , Análise de Regressão , Fatores de Risco , VirulênciaRESUMO
We present two interventions aimed at promoting science learning. We utilize arts-based assessments alongside traditional measures to examine systems thinking. Taking place in rural communities in Washington State and focusing on students in third through fifth grades, our results indicate that arts-based assessment in STEM can support demonstration of systems thinking about socio-scientific issues. We conclude by illustrating the viability of arts-based approaches for assessment and how these methods can complement and extend more traditional measures of learning in and out of the classroom.
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Agricultural intensification is a leading threat to bird conservation. Highly diversified farming systems that integrate livestock and crop production might promote a diversity of habitats useful to native birds foraging across otherwise-simplified landscapes. At the same time, these features might be attractive to nonnative birds linked to a broad range of disservices to both crop and livestock production. We evaluated the influence of crop-livestock integration on wild bird richness and density along a north-south transect spanning the U.S. West Coast. We surveyed birds on 52 farms that grew primarily mixed vegetables and fruits alone or integrated livestock into production. Crop-livestock systems harbored higher native bird density and richness relative to crop-only farms, a benefit more pronounced on farms embedded in nonnatural landscapes. Crop-livestock systems bolstered native insectivores linked to the suppression of agricultural pest insects but did not bolster native granivores that may be more likely to damage crops. Crop-livestock systems also significantly increased the density of nonnative birds, primarily European Starlings (Sturnus vulgaris) and House Sparrows (Passer domesticus) that may compete with native birds for resources. Models supported a small, positive correlation between nonnative density and overall native bird density as well as between nonnative density and native granivore density. Relative to crop-only farms, on average, crop-livestock systems exhibited 1.5 times higher patch richness, 2.4 times higher density of farm structures, 7.3 times smaller field sizes, 2.4 times greater integration of woody crops, and 5.3 times greater integration of pasture/hay habitat on farm. Wild birds may have responded to this habitat diversity and/or associated food resources. Individual farm factors had significantly lower predictive power than farming system alone (change in C statistic information criterion (ΔCIC) = 80.2), suggesting crop-livestock systems may impact wild birds through a suite of factors that change with system conversion. Collectively, our findings suggest that farms that integrate livestock and crop production can attract robust native bird communities, especially within landscapes devoted to intensified food production. However, additional work is needed to demonstrate persistent farm bird communities through time, ecophysiological benefits to birds foraging on these farms, and net effects of both native and nonnative wild birds in agroecosystems.
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Agricultura , Gado , Animais , Aves , Produtos Agrícolas , FazendasRESUMO
The northern fowl mite (NFM) Ornithonyssus sylviarum Canestrini and Fanzago is a blood-feeding ectoparasite found on many wild bird species and is a pest of poultry in the United States. It is unknown where NFM infestations of poultry originate, which has made it difficult to establish preventative biosecurity or effective control. We used microsatellite markers to evaluate genetic variation within and among NFM populations to determine routes of introduction onto farms and long-term persistence. We compared NFM from flocks of chickens (Gallus gallus) on different farms in California, Washington, and Georgia, and we compared NFM collected over a 5-yr interval. On three farms we collected NFM from chickens and house sparrows (Passer domesticus) nesting on each farm, which we used to assess movement between host species. There was strong genetic structure among mites from different poultry farms and low estimates of migration between farms. There were significant differences between mites on chickens and house sparrows on two farms where sparrows nested near flocks, indicating no exchange of mites. Only one farm showed evidence of NFM movement between chickens and sparrows. There was high genetic similarity between mites collected 5 yr apart on each of two farms, indicating that NFM infestations can persist for long periods. The genetic patterns did not reveal sources of NFM infestations on chicken farms. The data suggest that NFMs are strongly differentiated, which likely reflects periodic population declines with flock turnover and pesticide pressure.
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Doenças das Aves/parasitologia , Galinhas , Fluxo Gênico , Infestações por Ácaros/veterinária , Ácaros/genética , Pardais , Animais , California , Georgia , Infestações por Ácaros/parasitologia , Doenças das Aves Domésticas/parasitologia , WashingtonRESUMO
The number of prey killed by diverse predator communities is determined by complementarity and interference among predators, and by traits of particular predator species. However, it is less clear how predators' nonconsumptive effects (NCEs) scale with increasing predator biodiversity. We examined NCEs exerted on Culex mosquitoes by a diverse community of aquatic predators. In the field, mosquito larvae co-occurred with differing densities and species compositions of mesopredator insects; top predator dragonfly naiads were present in roughly half of surveyed water bodies. We reproduced these predator community features in artificial ponds, exposing mosquito larvae to predator cues and measuring resulting effects on mosquito traits throughout development. Nonconsumptive effects of various combinations of mesopredator species reduced the survival of mosquito larvae to pupation, and reduced the size and longevity of adult mosquitoes that later emerged from the water. Intriguingly, adding single dragonfly naiads to ponds restored survivorship of larval mosquitoes to levels seen in the absence of predators, and further decreased adult mosquito longevity compared with mosquitoes emerging from mesopredator treatments. Behavioral observations revealed that mosquito larvae regularly deployed "diving" escape behavior in the presence of the mesopredators, but not when a dragonfly naiad was also present. This suggests that dragonflies may have relaxed NCEs of the mesopredators by causing mosquitoes to abandon energetically costly diving. Our study demonstrates that adding one individual of a functionally unique species can substantially alter community-wide NCEs of predators on prey. For pathogen vectors like mosquitoes, this could in turn influence disease dynamics.
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Introduced parasites threaten native host species that lack effective defenses. Such parasites increase the risk of extinction, particularly in small host populations like those on islands. If some host species are tolerant to introduced parasites, this could amplify the risk of the parasite to vulnerable host species. Recently, the introduced parasitic nest fly Philornis downsi has been implicated in the decline of Darwin's finch populations in the Galápagos Islands. In some years, 100% of finch nests fail due to P. downsi; however, other common host species nesting near Darwin's finches, such as the endemic Galápagos mockingbird (Mimus parvulus), appear to be less affected by P. downsi. We compared effects of P. downsi on mockingbirds and medium ground finches (Geospiza fortis) on Santa Cruz Island in the Galápagos. We experimentally manipulated the abundance of P. downsi in nests of mockingbirds and finches to measure the direct effect of the parasite on the reproductive success of each species of host. We also compared immunological and behavioral responses by each species of host to the fly. Although nests of the two host species had similar parasite densities, flies decreased the fitness of finches but not mockingbirds. Neither host species had a significant antibody-mediated immune response to P. downsi. Moreover, finches showed no significant increase in begging, parental provisioning, or plasma glucose levels in response to the flies. In contrast, parasitized mockingbird nestlings begged more than nonparasitized mockingbird nestlings. Greater begging was correlated with increased parental provisioning behavior, which appeared to compensate for parasite damage. The results of our study suggest that finches are negatively affected by P. downsi because they do not have such behavioral mechanisms for energy compensation. In contrast, mockingbirds are capable of compensation, making them tolerant hosts, and a possible indirect threat to Darwin's finches.
Assuntos
Doenças das Aves/parasitologia , Espécies Introduzidas , Miíase/veterinária , Passeriformes , Envelhecimento , Animais , Comportamento Animal , Doenças das Aves/epidemiologia , Glicemia , Peso Corporal , Dípteros , Equador/epidemiologia , Feminino , Masculino , Miíase/epidemiologia , Miíase/parasitologia , Especificidade da EspécieRESUMO
The northern fowl mite, Ornithonyssus sylviarum, is the most damaging ectoparasite on egg-laying hens in the United States. One potential strategy for management is breeding for mite resistance. Genes of white leghorn chickens linked to the major histocompatibility complex (MHC) were previously identified as conferring more (B21 haplotype) or less (B15 haplotype) mite resistance. However, immune responses can be energetically costly to the host and affect the economic damage incurred from mite infestations. We tested energy costs (resting metabolic rate) of mite infestations on egg-laying birds of both MHC B-haplotypes. Resting metabolic rates were documented before (pre-) mite infestation, during (mid-) infestation, and after peak (late) mite infestation. Mite scores, economic parameters (egg production, feed consumption), and physiological aspects such as skin inflammation and skin temperature were recorded weekly. Across experiments and different infestation time points, resting metabolic rates generally were not affected by mite infestation or haplotype, although there were instances of lower metabolic rates in infested versus control hens. Skin temperatures were recorded both at the site of mite feeding damage (vent) and under the wing (no mites), which possibly would reflect a systemic fever response. Ambient temperatures modified skin surface temperature, which generally was not affected by mites or haplotype. Feed conversion efficiency was significantly worse (4.9 to 17.0% depending on trial) in birds infested with mites. Overall egg production and average egg weight were not affected significantly, although there was a trend toward reduced egg production (2 to 8%) by infested hens. The MHC haplotype significantly affected vent skin inflammation. Birds with the mite-resistant B21 haplotype showed earlier onset of inflammation, but a reduced overall area of inflammation compared to mite-susceptible B15 birds. No significant differences in resting energy expenditure related to mite infestation or immune responses were detected. Potential breeding for resistance to mite infestation using these two haplotypes appears to be neutral in terms of impact on hen energy costs or production efficiency, and may be an attractive option for future mite control.
Assuntos
Metabolismo Basal , Galinhas , Complexo Principal de Histocompatibilidade , Infestações por Ácaros/veterinária , Ácaros/fisiologia , Doenças das Aves Domésticas/parasitologia , Animais , Feminino , Haplótipos , Infestações por Ácaros/genética , Infestações por Ácaros/metabolismo , Infestações por Ácaros/parasitologia , Doenças das Aves Domésticas/genética , Doenças das Aves Domésticas/metabolismoRESUMO
Introduced parasites threaten native host species that lack effective defenses. Such parasites increase the risk of extinction, particularly in small host populations like those on islands. If some host species are tolerant to introduced parasites, this could amplify the risk of the parasite to vulnerable host species. Recently, the introduced parasitic nest fly Philornis downsi has been implicated in the decline of Darwin's finch populations in the Galápagos Islands. In some years, 100% of finch nests fail due to P. downsi; however, other common host species nesting near Darwin's finches, such as the endemic Galápagos mockingbird (Mimus parvulus), appear to be less affected by P. downsi. We compared effects of P. downsi on mockingbirds and medium ground finches (Geospiza fortis) on Santa Cruz Island in the Galápagos. We experimentally manipulated the abundance of P. downsi in nests of mockingbirds and finches to measure the direct effect of the parasite on the reproductive success of each species of host. We also compared immunological and behavioral responses by each species of host to the fly. Although nests of the two host species had similar parasite densities, flies decreased the fitness of finches but not mockingbirds. Neither host species had a significant antibody-mediated immune response to P. downsi. Moreover, finches showed no significant increase in begging, parental provisioning, or plasma glucose levels in response to the flies. In contrast, parasitized mockingbird nestlings begged more than nonparasitized mockingbird nestlings. Greater begging was correlated with increased parental provisioning behavior, which appeared to compensate for parasite damage. The results of our study suggest that finches are negatively affected by P. downsi because they do not have such behavioral mechanisms for energy compensation. In contrast, mockingbirds are capable of compensation, making them tolerant hosts, and a possible indirect threat to Darwin's finches.