scholarly journals Agricultural pesticides and ectoparasites: potential combined effects on the physiology of a declining aerial insectivore

2021 ◽  
Vol 9 (1) ◽  
Author(s):  
Audrey Sigouin ◽  
Marc Bélisle ◽  
Dany Garant ◽  
Fanie Pelletier
Keyword(s):  
Multiple Stressors ◽  
Synergistic Effects ◽  
Tree Swallow ◽  
Pest Species ◽  
Agricultural Pesticides ◽  
Toxicological Effects ◽  
Aerial Insectivore ◽  
Aerial Insectivores ◽  
Bacteria Killing ◽  
Natural Settings

Abstract Agricultural pesticides usage has been increasing globally. These compounds have been developed to disrupt pest species physiology, but because their specificity is limited, they can also have adverse effects on non-target organisms. Recent studies have shown that the damaging toxicological effects of pesticides can be amplified in stressful environments. However, few studies have documented these effects in natural settings where organisms are simultaneously exposed to pesticides and to other environmental stressors such as parasites. In this study, we assessed both pesticide and ectoparasite effects on the physiology of a free-ranging bird. We measured physiological markers including haematocrit, bacteria-killing ability (BKA) and leucocyte counts, as well as exposure to haematophagous Protocalliphora larvae, in tree swallow nestlings (Tachycineta bicolor), a declining aerial insectivore, in southern Québec, Canada, for over 3 years. We found that combined exposure to pesticides and Protocalliphora larvae was negatively related to haematocrit, suggesting possible synergistic effects. However, we found no such relationships with BKA and leucocyte counts, highlighting the complexity of physiological responses to multiple stressors in natural settings. Populations of several aerial insectivores are declining, and although sublethal pesticide effects on physiology are suspected, our results suggest that exposure to other factors, such as parasitism, should also be considered to fully assess these effects, especially because pesticides are increasingly present in the environment.

scholarly journals Omega-3 long-chain polyunsaturated fatty acids support aerial insectivore performance more than food quantity

2016 ◽  
Vol 113 (39) ◽  
pp. 10920-10925 ◽  
Author(s):  
Cornelia W. Twining ◽  
J. Thomas Brenna ◽  
Peter Lawrence ◽  
J. Ryan Shipley ◽  
Troy N. Tollefson ◽  
...  
Keyword(s):  
Fatty Acid Composition ◽  
Fatty Acid ◽  
Acid Composition ◽  
Tree Swallow ◽  
Omega 3 ◽  
Food Quantity ◽  
Aerial Insectivore ◽  
Aerial Insectivores ◽  
Terrestrial Insects ◽  
Long Chain

Once-abundant aerial insectivores, such as the Tree Swallow (Tachycineta bicolor), have declined steadily in the past several decades, making it imperative to understand all aspects of their ecology. Aerial insectivores forage on a mixture of aquatic and terrestrial insects that differ in fatty acid composition, specifically long-chain omega-3 polyunsaturated fatty acid (LCPUFA) content. Aquatic insects contain high levels of both LCPUFA and their precursor omega-3 PUFA, alpha-linolenic acid (ALA), whereas terrestrial insects contain much lower levels of both. We manipulated both the quantity and quality of food for Tree Swallow chicks in a full factorial design. Diets were either high-LCPUFA or low in LCPUFA but high in ALA, allowing us to separate the effects of direct LCPUFA in diet from the ability of Tree Swallows to convert their precursor, ALA, into LCPUFA. We found that fatty acid composition was more important for Tree Swallow chick performance than food quantity. On high-LCPUFA diets, chicks grew faster, were in better condition, and had greater immunocompetence and lower basal metabolic rates compared with chicks on both low LCPUFA diets. Increasing the quantity of high-LCPUFA diets resulted in improvements to all metrics of performance while increasing the quantity of low-LCPUFA diets only resulted in greater immunocompetence and lower metabolic rates. Chicks preferentially retained LCPUFA in brain and muscle when both food quantity and LCPUFA were limited. Our work suggests that fatty acid composition is an important dimension of aerial insectivore nutritional ecology and reinforces the importance of high-quality aquatic habitat for these declining birds.

Phenotypic differences among wild passerine nestlings in relation to early-life rearing environment

2021 ◽  
Author(s):  
Jesús Gómez ◽  
Christy Morrissey ◽  
Sonia Cabezas ◽  
Tracy Marchant ◽  
Robert Clark
Keyword(s):  
Land Use ◽  
Body Condition ◽  
Early Life ◽  
Agricultural Land ◽  
Developmental Stages ◽  
Tree Swallow ◽  
Phenotypic Differences ◽  
Aerial Insectivore ◽  
Fledgling Survival ◽  
Insect Populations

Subtle changes in stress physiology during critical developmental stages have been linked to long-term fitness; however, the biological processes and phenotypic responses to early-life rearing environments such as anthropogenic land use conditions, have not been fully evaluated in insectivorous birds. We manipulated Tree Swallow, Tachycineta bicolor (Vieillot, 1808), brood sizes at sites with contrasting agricultural land use to assess phenotypic changes in body condition and genetic and physiological biomarkers of stress during the sensitive nestling growth phase. We predicted that nestling swallows raised on cropland-dominated sites, especially those in enlarged broods, would have lower body condition, shorter telomeres, and higher feather corticosterone than nestlings raised in smaller broods at grassland sites. Body condition was highest among nestlings raised in reduced broods but was unrelated to land use. Telomere lengths tended to be shorter in nestlings from enlarged broods and at cropland sites. Corticosterone was not related to any factor. Locally-abundant insect populations associated with wetlands may have dampened the effects and/or parent swallows assumed higher costs of reproduction rather than passing these costs to nestlings. Results suggest that food stress could reduce fledgling survival via telomere shortening; a hypothesis that requires further investigation due to its potential importance to population viability in multiple declining aerial insectivore species.

scholarly journals Interacting effects of cold snaps, rain, and agriculture on the fledging success of a declining aerial insectivore

2021 ◽  
Author(s):  
Daniel Roy Garrett ◽  
Fanie Pelletier ◽  
Dany Garant ◽  
Marc Bélisle
Keyword(s):  
Climate Change ◽  
Agricultural Intensification ◽  
Prey Availability ◽  
Tree Swallow ◽  
Landscape Changes ◽  
Population Declines ◽  
Negative Effects ◽  
Fledging Success ◽  
Inclement Weather ◽  
Aerial Insectivore

Climate change predicts the increased frequency, duration, and intensity of inclement weather periods, such as unseasonably low temperatures and prolonged precipitation. Many migratory species have advanced the phenology of important life history stages, and as a result are likely exposed to these periods of inclement spring weather more often, thus risking reduced fitness and population growth. For declining avian species, including aerial insectivores, anthropogenic landscape changes such as agricultural intensification are another driver of population declines. These landscape changes may affect the foraging ability of food provisioning parents, as well as reduce the probability a nestling will survive periods of inclement weather, through for example pesticide exposure impairing thermoregulation and punctual anorexia. Breeding in agro-intensive landscapes may thus exacerbate the negative effects of inclement weather under climate change. We used daily temperatures related to significant reductions of insect prey availability (cold snaps), combined with measures of precipitation, and assessed their impact on Tree Swallow (Tachycineta bicolor) fledging success, a declining aerial insectivore breeding across a gradient of agricultural intensification. Fledging success decreased with the number of cold snap days experienced by a brood, and this relationship was worsened during periods of prolonged precipitation. We further found the overall negative effects of experiencing periods of inclement weather are exacerbated in more agro-intensive landscapes. Our results indicate that two of the primary hypothesized drivers of many avian population declines may interact to further increase the rate of declines in certain landscape contexts.

Endogenous biomarkers reveal diet partitioning among three sympatric species of swallows

The Auk ◽  
2021 ◽  
Author(s):  
Kaelyn H Bumelis ◽  
Michael D Cadman ◽  
Keith A Hobson
Keyword(s):  
Isotope Analysis ◽  
Sympatric Species ◽  
Tree Swallow ◽  
Population Declines ◽  
Interspecific Differences ◽  
Cliff Swallow ◽  
Aerial Insectivores ◽  
Breeding Grounds ◽  
Potential Factors ◽  
Δ 15N

Abstract Since the early 1990s, aerial insectivorous birds have shown serious population declines in North America, but it is not clear if factors common to all species within this guild account for these declines. Among sympatric swallows, population trends differ, and this may be due to differences in ecology operating throughout the annual cycle. Although these species all feed on aerial insects, prey taxa can differ tremendously in their “aeroecology” and use by swallows. We examined the potential for dietary differences among three species of swallows, Barn Swallow (Hirundo rustica), Cliff Swallow (Petrochelidon pyrrhonota), and Tree Swallow (Tachycineta bicolor), breeding sympatrically in southern Ontario, Canada. Potential interspecific differences in nestling diet were examined using two endogenous biomarkers, DNA barcoding of nestling feces and stable isotope analysis (δ 2H, δ 13C, δ 15N) of nestling feathers. We found evidence for differences in dietary sources of provisioned young where Barn Swallows provisioned more terrestrial-based prey, Cliff Swallows provisioned an intermediate diet, and Tree Swallows the most aquatic-emergent insect diet. We suggest this information may help to identify potential factors contributing to differential declines of aerial insectivores operating on the breeding grounds, including diet quality.

Can Indirect Herbicide Exposure Modify the Response of the Colorado Potato Beetle to an Organophosphate Insecticide?

2019 ◽  
Vol 112 (5) ◽  
pp. 2316-2323 ◽  
Author(s):  
Aigi Margus ◽  
Miia Rainio ◽  
Leena Lindström
Keyword(s):  
Colorado Potato Beetle ◽  
Target Genes ◽  
Multiple Stressors ◽  
Synergistic Effects ◽  
Oxidative Status ◽  
Interactive Effects ◽  
Invasive Pest ◽  
Lipid Hydroperoxides ◽  
Organophosphate Insecticide ◽  
Potato Beetle

AbstractOrganisms live in complex multivariate environments. In agroecosystems, this complexity is often human-induced as pest individuals can be exposed to many xenobiotics simultaneously. Predicting the effects of multiple stressors can be problematic, as two or more stressors can have interactive effects. Our objective was to investigate whether indirect glyphosate-based herbicide (GBH) exposure of the host plant has interactive effects in combination with an insecticide (azinphos-methyl) on an invasive pest Colorado potato beetle (Leptinotarsa decemlineata Say). We tested the effects of GBH and insecticide on the survival, insecticide target genes expression (acetylcholinesterase genes) and oxidative status biomarkers (glutathione S-transferase [GST], glucose-6-phosphate dehydrogenase [G6PDH], glutathione reductase homolog [GR], glutathione peroxidase homolog [GPx], total glutathione [totGSH], glutathione reduced-oxidized [GSH: GSSG], catalase [CAT], superoxide dismutase [SOD], lipid hydroperoxides). We found that exposure to indirect GBH has no single or interactive effects in combination with the insecticide on larval survival. However, prior exposure to GBH inhibits Ldace1 gene expression by 0.55-fold, which is the target site for the organophosphate and carbamate insecticides. This difference disappears when individuals are exposed to both GBH and insecticide, suggesting an antagonistic effect. On the other hand, oxidative status biomarker scores (PCAs of GPx, GR, and CAT) were decreased when exposed to both stressors, indicating a synergistic effect. Overall, we found that indirect GBH exposure can have both antagonistic and synergistic effects in combination with an insecticide, which should be considered when aiming for an ecologically relevant risk assessment of multiple human-induced stressors.

Evidence for multiple drivers of aerial insectivore declines in North America

The Condor ◽  
2019 ◽  
Vol 121 (2) ◽  
Author(s):  
Kimberly J Spiller ◽  
Randy Dettmers
Keyword(s):  
North America ◽  
Habitat Loss ◽  
Prey Abundance ◽  
Research Progress ◽  
Current Evidence ◽  
High Quality ◽  
Prey Quality ◽  
Aerial Insectivore ◽  
Starting Point ◽  
Aerial Insectivores

Abstract Aerial insectivores (birds that forage on aerial insects) have experienced significant population declines in North America. Numerous hypotheses have been proposed for these declines, but current evidence suggests multiple factors could be operating in combination during their annual migratory cycles between breeding and nonbreeding areas. Potential drivers include decreased prey abundance, direct or indirect impacts of environmental contaminants, habitat loss, phenological changes due to warming climate, and conditions on migratory stopover or wintering grounds. While no single threat appears to be the cause of aerial insectivore declines, existing evidence suggests that several of these factors could be contributing to the declines at different times in the annual lifecycle. Breeding productivity for most of these species does not appear to be limited by overall prey abundance, contaminants, or habitat loss, which suggests that similar issues on nonbreeding grounds or carryover effects could play important roles. However, a better understanding of the importance of prey quality throughout the lifecycle is critically needed. Based on current evidence, we propose that changes in availability of high-quality prey, with variability across breeding and nonbreeding grounds, reduce various combinations of fledging success, post-fledging survival, and nonbreeding season body condition of aerial insectivores, resulting in species and geographic differences in population trends. We encourage others to use this hypothesis as a starting point to test specific mechanisms by which availability of high-quality prey influences demographic parameters. We suggest that future research focus on defining prey quality, monitoring insect abundance in conjunction with birds, comparing demographic models across local populations experiencing different population growth rates, and using tracking technology to document important migratory and nonbreeding areas. Considerable research progress already has been made, but additional research is needed to better understand the complex web of potential causes driving aerial insectivore declines.

scholarly journals Wind and rain are the primary climate factors driving changing phenology of an aerial insectivore

2017 ◽  
Vol 284 (1853) ◽  
pp. 20170412 ◽  
Author(s):  
Rachel D. Irons ◽  
April Harding Scurr ◽  
Alexandra P. Rose ◽  
Julie C. Hagelin ◽  
Tricia Blake ◽  
...  
Keyword(s):  
Climate Change ◽  
Natural Populations ◽  
Climate Change Impacts ◽  
Tree Swallow ◽  
Breeding Phenology ◽  
Climate Conditions ◽  
Aerial Insectivore ◽  
Windy Weather ◽  
Two Measures

While the ecological effects of climate change have been widely observed, most efforts to document these impacts in terrestrial systems have concentrated on the impacts of temperature. We used tree swallow ( Tachycineta bicolor ) nest observations from two widely separated sites in central Alaska to examine the aspects of climate affecting breeding phenology at the northern extent of this species' range. We found that two measures of breeding phenology, annual lay and hatch dates, are more strongly predicted by windiness and precipitation than by temperature. At our longest-monitored site, breeding phenology has advanced at nearly twice the rate seen in more southern populations, and these changes correspond to long-term declines in windiness. Overall, adverse spring climate conditions known to negatively impact foraging success of swallows (wet, windy weather) appear to influence breeding phenology more than variation in temperature. Separate analyses show that short windy periods significantly delay initiation of individual clutches within years. While past reviews have emphasized that increasing variability in climate conditions may create physiological and ecological challenges for natural populations, we find that long-term reductions in inclement weather corresponded to earlier reproduction in one of our study populations. To better predict climate change impacts, ecologists need to more carefully test effects of multiple climate variables, including some, like windiness, that may be of paramount importance to some species, but have rarely been considered as strong drivers of ecological responses to climate alteration.

scholarly journals Predictors of nestling survival during harsh weather events in an aerial insectivore, the Tree Swallow (Tachycineta bicolor)

2019 ◽  
Vol 97 (2) ◽  
pp. 81-90 ◽  
Author(s):  
Ilsa A. Griebel ◽  
Russell D. Dawson
Keyword(s):  
Heat Treating ◽  
Tachycineta Bicolor ◽  
Tree Swallow ◽  
Extreme Weather Events ◽  
Curvilinear Relationship ◽  
Bird Populations ◽  
Inclement Weather ◽  
Aerial Insectivore ◽  
Weather Events ◽  
Nestling Survival

Extreme weather events influence the population dynamics of wild animals. For organisms whose food source is affected by environmental conditions, such as aerial insectivorous birds, periods of inclement weather can have devastating effects. Here, we examine predictors of survival of individual nestlings and whole broods in Tree Swallows (Tachycineta bicolor (Vieillot, 1808)) during an extreme, 2-day harsh weather event in central British Columbia, Canada, which co-occurred with experimental reduction of nest ectoparasite loads using an antiparasite drug (ivermectin) or heat-treating nests. A curvilinear relationship existed between survival and brood age such that middle-aged broods were least likely to survive. Survival of broods and nestlings was higher when raised by males with bluer plumage, whereas nestling survival was lower when female parents had brighter and more UV-reflective plumage. Within broods, smaller nestlings had a lower chance of surviving than their larger siblings. Nestlings in broods where half of the offspring received ivermectin injections had significantly higher chances of surviving than nestlings from nonexperimental broods, suggesting that parasite loads can influence survival during inclement weather. Our results identify several factors influencing resiliency of nestlings to harsh weather and are particularly relevant in the context of declining aerial insectivorous bird populations and climate change.

Effect of Chemical Pollution and Parasitism on Heat Tolerance in Dung Beetles (Coleoptera: Scarabaeinae)

2020 ◽  
Author(s):  
Daniel González-Tokman ◽  
Yorleny Gil-Pérez ◽  
Mariana Servín-Pastor ◽  
Fredy Alvarado ◽  
Federico Escobar ◽  
...  
Keyword(s):  
Ecosystem Services ◽  
Heat Tolerance ◽  
Multiple Stressors ◽  
Physiological Stress ◽  
Synergistic Effects ◽  
Dung Beetles ◽  
Chemical Pollution ◽  
Cattle Dung ◽  
Immune Challenge ◽  
Environmental Pressures

Abstract Ecosystem services provided by insects are threatened by recent increasing global temperatures, particularly in the tropics, where insects live close to their thermal limits. Given that tolerance to high temperatures depends on individual metabolism and physiological stress response, it may also be sensitive to other stressors that are common in natural and human-modified environments, such as pollution and parasite pressure. The effects of multiple stressors could be synergistic and can be particularly relevant in insects that provide highly valuable ecosystem services, such as dung beetles in cattle pastures. Here we measured heat tolerance (critical thermal maximum, CTmax) in dung beetles exposed to ivermectin, a toxic parasiticide excreted in cattle dung, with known negative effects on coprophagous fauna, and in beetles exposed to an immune challenge. We also exposed a group of beetles to a combination of both ivermectin and immune challenge to test for potential synergistic effects of both stressors. Contrary to our predictions, CTmax did not change with ivermectin exposure, but increased in immune-challenged beetles. As found in other insects, CTmax was higher in larger beetles, highlighting the importance of body size on thermal tolerance in ectotherms. We discuss potential mechanisms responsible of increased heat tolerance in immune-challenged beetles and highlight the importance of natural and human-induced environmental pressures that now interact with global warming and threaten ecosystem services provided by wild animals.

A multivariate approach to assess habitat integrity in urban streams using benthic macroinvertebrate metrics

2013 ◽  
Vol 67 (12) ◽  
pp. 2832-2837 ◽  
Author(s):  
S. Canobbio ◽  
A. Azzellino ◽  
R. Cabrini ◽  
V. Mezzanotte
Keyword(s):  
Habitat Loss ◽  
Multiple Stressors ◽  
Synergistic Effects ◽  
Freshwater Ecosystems ◽  
Urban Streams ◽  
Anthropogenic Pressure ◽  
Multivariate Approach ◽  
Urban District ◽  
Morphological Alterations ◽  
Macroinvertebrate Metrics

Benthic macroinvertebrates are widely used as indicators of the health of freshwater ecosystems, responding both to water quality and to the hydromorphological integrity. In urban streams, evaluations can be tricky for the synergistic effects of multiple stressors and confounding factors. In these situations, the most broadly used multimetric indices can be used to assess the overall damage to the invertebrate community and, thus, the overall anthropogenic pressure, but they do not allow to understand the specific causal effects. Particularly, habitat loss due to morphological alterations can be difficult to evaluate, especially due to the often concurrent disturbance caused by water pollution. We used a multivariate approach to focus on the characteristics of the streams and rivers in an urban district and to define which macroinvertebrate metrics should be used to assess the influence of the different kinds of alteration in a severely damaged environment. Some metrics enabling the assessment of habitat loss (ratio of oligochaeta, ratio of filterers) were identified. These metrics may help to raise a better awareness in the evaluation of river restoration success and, thus, in the support of decision-making processes.

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