Primary consumers are under strong selection from resource (‘bottom‐up’) and consumer (‘top‐down’) controls, but the relative importance of these selective forces is unknown. We performed a ...meta‐analysis to compare the strength of top‐down and bottom‐up forces on consumer fitness, considering multiple predictors that can modulate these effects: diet breadth, feeding guild, habitat/environment, type of bottom‐up effects, type of top‐down effects and how consumer fitness effects are measured. We focused our analyses on the most diverse group of primary consumers, herbivorous insects, and found that in general top‐down forces were stronger than bottom‐up forces. Notably, chewing, sucking and gall‐making herbivores were more affected by top‐down than bottom‐up forces, top‐down forces were stronger than bottom‐up in both natural and controlled (cultivated) environments, and parasitoids and predators had equally strong top‐down effects on insect herbivores. Future studies should broaden the scope of focal consumers, particularly in understudied terrestrial systems, guilds, taxonomic groups and top‐down controls (e.g. pathogens), and test for more complex indirect community interactions. Our results demonstrate the surprising strength of forces exerted by natural enemies on herbivorous insects, and thus the necessity of using a tri‐trophic approach when studying insect‐plant interactions.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
The Sexual Experiences Survey (SES), the most widely used measure of unwanted sexual experiences, was recently updated (Koss et al., 2007). The purpose of this study was to provide psychometric data ...on the updated Sexual Experiences Survey-Short Form Perpetration (SES-SFP) and the Sexual Experiences Survey-Short Form Victimization (SES-SFV). Men (n = 136) and women (n = 433) were randomly assigned to in-person or Internet formats of administration for 3 measurement points. Women completed victimization surveys and trauma measures. Men completed perpetration surveys and attitude/ personality measures. Results supported the validity and reliability of both the SES-SFV with women and the SES-SFP with men. Further research is needed regarding the use of the SES-SFV with men and the SES-SFP with women.
Abstract
Background
Insurance claims data have been used to inform an understanding of Lyme disease epidemiology and cost of care, however few such studies have incorporated post-treatment symptoms ...following diagnosis. Using longitudinal data from a private, employer-based health plan in an endemic US state, we compared outpatient care utilization pre- and post-Lyme disease diagnosis. We hypothesized that utilization would be higher in the post-diagnosis period, and that temporal trends would differ by age and gender.
Methods
Members with Lyme disease were required to have both a corresponding ICD-9 code and a fill of an antibiotic indicated for treatment of the infection within 30 days of diagnosis. A 2-year ‘pre- diagnosis’ period and a 2-year ‘post-diagnosis period’ were centered around the diagnosis month. Lyme disease-relevant outpatient care visits were defined as specific primary care, specialty care, or urgent care visits. Descriptive statistics examined visits during these pre- and post-diagnosis periods, and the association between these periods and the number of visits was explored using generalized linear mixed effects models adjusting for age, season of the year, and gender.
Results
The rate of outpatient visits increased 26% from the pre to the post-Lyme disease diagnosis periods among our 317-member sample (rate ratio = 1.26 1.18, 1.36,
p
< 0.001). Descriptively, care utilization increases appeared to persist across months in the post-diagnosis period. Women’s care utilization increased by 36% (1.36 1.24, 1.50,
p
< 0.001), a significantly higher increase than the 14% increase found among men (1.14 1.02, 1.27,
p
= 0.017). This gender difference was mainly driven by adult members. We found a borderline significant 17% increase in visits for children < 18 years, (1.17 0.99, 1.38,
p
= 0.068), and a 31% increase for adults ≥ 18 years (1.31 1.21, 1.42,
p
< 0.001).
Conclusions
Although modest at the population level, the statistically significant increases in post-Lyme diagnosis outpatient care we observed were persistent and unevenly distributed across demographic and place of service categories. As Lyme disease cases continue to grow, so will the cumulative prevalence of persistent symptoms after treatment. Therefore, it will be important to confirm these findings and understand their significance for care utilization and cost, particularly against the backdrop of other post-acute infectious syndromes.
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CEKLJ, DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Light pollution is a global disturbance with resounding impacts on a wide variety of organisms, but our understanding of these impacts is restricted to relatively few higher vertebrate species. We ...tested the direct effects of light pollution on herbivore performance as well as indirect effects mediated by host plant quality. We found that artificial light from streetlights alters plant toughness. Additionally, we found evidence of both direct and indirect effects of light pollution on the performance of an herbivorous insect, which indicates that streetlights can have cascading impacts on multiple trophic levels. Our novel findings suggest that light pollution can alter plant–insect interactions and thus may have important community‐wide consequences.
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FZAB, GIS, IJS, IZUM, KILJ, NLZOH, NUK, OILJ, PILJ, PNG, SAZU, SBCE, SBMB, UL, UM, UPUK
Context
Historically, habitat edges were thought to increase diversity by combining communities from two habitats, but empirical results are mixed. Variation in edge responses may be driven by ...lumping specialists and generalists with divergent responses.
Objectives
We examined arthropod communities associated with a habitat edge in an intertidal salt marsh in New Jersey. We predicted that herbivores, largely specialists, would decline along the habitat edge due to their failure to expand across the boundary, and specialist natural enemies should track prey. Generalists should be less impacted by the edge if they use resources from both sides. Thus, habitat edges should affect species composition more than species diversity.
Methods
We studied the edge responses of 115 arthropod species to the habitat edge formed between
Spartina patens
(SP) and
Spartina alterniflora
(SA) throughout the growing season.
Results
We found that the edge between SA and SP affected the abundance and composition of the associated arthropod community, but not species richness. Composition of herbivores, epigeic feeders, specialist natural enemies, and generalist predators shifted not only between SA and SP interiors, but also the edges. Compositional shifts were driven by dietary or habitat specialists.
Conclusions
We found that edges change community composition via divergent responses by species with different resource requirements. This change in composition is not between two disparate habitat types but two congeneric grass species. Our results demonstrate that biodiversity losses due to edge effects associated with habitat fragmentation will not be random but will be driven by specialization and resource use.
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EMUNI, FZAB, GEOZS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
Generalist predators are thought to be less vulnerable to habitat fragmentation because they use diverse resources across larger spatial scales than specialist predators. Thus, it has been suggested ...that generalist predators may respond positively to habitat edges or demonstrate no edge response, because they can potentially use prey resources equally well on both sides of the habitat edge. However, most predictions about generalist predator responses to the habitat edge are based solely on prey resources, without consideration of other potential drivers. For instance, structural resources are essential for some species to build webs to capture prey or to avoid intraguild predation and cannibalism. In this study, we used both prey and structural resources to predict the response of four predator functional groups (hunting spiders, web-building spiders, aerial predators, and epigeic predators that feed on the detrital/algal food web) to a habitat edge between two salt-marsh grasses (Spartina alterniflora and Spartina patens). We found that generalist predators largely demonstrated negative responses to the habitat edge and had distinct habitat associations. Positive edge responses were only observed in one functional group (hunting spiders), and this pattern was driven by the two most abundant species. Negative responses to the habitat edge were more common among taxa and were better explained by structural resources rather than prey resources in the two habitats. Although it is generally acknowledged that specialists decline in fragmented habitats, generalists are thought to be more resilient. However, our research demonstrates that even generalists have habitat structural or food resource requirements that may limit their resilience to habitat loss and fragmentation.
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BFBNIB, FZAB, GIS, IJS, INZLJ, KILJ, NLZOH, NMLJ, NUK, OILJ, PNG, SAZU, SBCE, SBMB, UL, UM, UPUK, ZRSKP
Ecological studies investigating the effects of artificial light at night (ALAN) have primarily focused on single or a few species, and seldom on community-level dynamics. As ALAN is a potential ...cause of insect and biodiversity declines, community-level perspectives are essential. We empirically tested the hypothesis that moth species differentially respond to ALAN and that these responses can cause shifts in community composition. We sampled moths from prairie fragments in Colorado, USA. We tested whether local light sources, sky glow, site area and/or vegetation affected moth community diversity. We found that increased sky glow decreased moth abundance and species richness and shifted community composition. Increased sky glow shifted moth community composition when light and bait traps were combined; notably this result appears to be driven entirely by moths sampled at bait traps, which is an unbiased sampling technique. Our results show that ALAN has significant effects on moth communities and that local light sources have contrasting effects on moth community composition compared to sky glow. It is imperative that we better understand the contrasting effects of types of ALAN to comprehend the overall impacts of light pollution on biodiversity declines.
This article is part of the theme issue ‘Light pollution in complex ecological systems’.
The effects of competition can have far‐reaching consequences for individuals, populations, and communities and therefore we should strive toward a deeper understanding of competitive interactions. ...In some cases, dietary generalists may be predicted to experience weak competition effects because of their ability to use a wide range of host plants. However, competition between insects frequently occurs indirectly, which can hinder insects' abilities to avoid competitive interactions. Therefore, competition may be as strong among dietary generalists as among dietary specialists. Yet competition between insects that are dietary generalists is infrequently studied. We tested for evidence of competitive interactions between two common, temporally separated, generalist insects: the western tent caterpillar (Malacosoma californicum), which feeds early in the season, and the fall webworm (Hyphantria cunea), which feeds later in the season. Both species frequently use a common host plant species (chokecherry) as a preferred host at our field sites. We tested the relative strength of bottom‐up effects resulting from competitive interactions between these two generalists with laboratory‐rearing trials at the relevant time of year for each insect. We recorded three common fitness measures (development time, pupal mass, and survival) for caterpillars reared on chokecherry with no damage from either of our focal species, with tent caterpillar damage, and with fall webworm damage. To test the strength of top‐down pressures on fall webworm larval fitness and any potential interactions with bottom‐up effects, we reared larvae in the field either exposed to or protected from predators on host plants that either did or did not have tent caterpillars feeding on them earlier in the season. We found evidence of bottom‐up fitness effects on tent caterpillars and top‐down and bottom‐up fitness effects on fall webworms confirming that tent caterpillars and fall webworms compete indirectly. Tent caterpillars had lower pupal mass when reared on leaves from shrubs damaged by fall webworms. Fall webworms had lower pupal mass and longer development time when reared on leaves from shrubs damaged by tent caterpillars. In field trials, fall webworms reared on shrubs damaged by tent caterpillars had a lower survival and pupal mass. We show evidence of indirect competition in temporally separated generalists through leaf quality (bottom‐up effects) and natural enemies (top‐down effects).
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Natural enemies can be significant sources of mortality for herbivorous insects and therefore important agents of natural selection. One might expect selection to favor herbivores that escape from ...their natural enemies into enemy-free space. Although this is an appealing idea, it has received little empirical support, and no studies have documented enemy-free space as part of a nonagricultural, nonartificial host shift. The Alaskan swallowtail butterfly, Papilio machaon aliaska, uses as host plants a species in the family Apiaceae (Cnidium cnidiifolium) along with two Asteraceae species (Artemisia arctica and Petasites frigidus). I analyzed growth and survival of P. m. aliaska larvae in the field on the three host plants in treatments that either exposed or protected them from predators. I found that, in the presence of predators, larval survival is greater on the novel hosts (Asteraceae) than on the ancestral host (Apiaceae), but that in the absence of predators survival and growth are greater on the ancestral host. These results are a demonstration of enemy-free space as a mechanism for maintaining a naturally occurring host shift.
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BFBNIB, NMLJ, NUK, PNG, SAZU, UL, UM, UPUK
Hepatic TANK (TRAF family member associated NFκB activator)-binding kinase 1 (TBK1) activity is increased during obesity, and administration of a TBK1 inhibitor reduces fatty liver. Surprisingly, ...liver-specific TBK1 knockout in mice produces fatty liver by reducing fatty acid oxidation. TBK1 functions as a scaffolding protein to localize acyl-CoA synthetase long-chain family member 1 (ACSL1) to mitochondria, which generates acyl-CoAs that are channeled for β-oxidation. TBK1 is induced during fasting and maintained in the unphosphorylated, inactive state, enabling its high affinity binding to ACSL1 in mitochondria. In TBK1-deficient liver, ACSL1 is shifted to the endoplasmic reticulum to promote fatty acid re-esterification in lieu of oxidation in response to fasting, which accelerates hepatic lipid accumulation. The impaired fatty acid oxidation in TBK1-deficient hepatocytes is rescued by the expression of kinase-dead TBK1. Thus, TBK1 operates as a rheostat to direct the fate of fatty acids in hepatocytes, supporting oxidation when inactive during fasting and promoting re-esterification when activated during obesity.
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•Hepatic TBK1 activity is reduced by fasting while elevated by obesity•Liver-specific TBK1 KO mice exhibit increased liver lipid due to less fat oxidation•Fasting-stimulated mitochondrial localization of ACSL1 is impaired in TBK1 KO mice•Inactive TBK1 rescues fatty acid oxidation, suggesting a scaffolding function
Huh et al. demonstrate that TBK1 is necessary for fasting-induced fat oxidation in liver via channeling substrates to mitochondria. While obesity increases the kinase activity of TBK1, fasting reduces its activity, which elevates the inactive TBK1 to support more efficient fat oxidation. This pathway may contribute to the mechanism by which TBK1 inhibitors improve fatty liver.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
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