The benefits of ant-plant-herbivore interactions for the plant depend on the abundance of ants and herbivores and the selective pressures these arthropods exert. In plants bearing extrafloral nectaries (EFN), different mean trait values may be selected for by different populations in response to local herbivore pressure, ultimately resulting in the evolution of differences in plant traits that attract ants as defensive agents against herbivory. To determine if variation in traits that mediate ant-plant interactions reflect herbivore selective pressures, we quantified intra- and inter-population variation in plant traits for eight populations of the EFN-bearing annual Chamaecrista fasciculata (Michx.) (Fabaceae). Censuses in rural and urban areas of Missouri and Illinois (USA) showed population differences in ant attendance and herbivore pressure. Seeds were collected from each population, and plants were grown in a common greenhouse environment to measure sugar production, nectar volume and composition, EFN size and time of emergence, leaf pubescence, and leaf quality throughout plant development. Populations varied mainly in terms of nectary size, sugar production, and nectar volume, but to a lesser degree in leaf pubescence. Populations of C. fasciculata within urban areas (low in insect abundance) had small nectaries and the lowest nectar production. There was a positive correlation across populations between herbivore density and leaf damage by those herbivores on the one hand and sugar production and nectar volume on the other. These results, in conjunction with lack of evidence for maternally based environmental effects, suggest that population differences in herbivore damage have promoted differential evolution of EFN-related traits among populations.
Many Latino horse workers experienced upper and lower respiratory symptoms. Dust mask use may protect workers in this and other enclosed livestock operations from respiratory symptoms.
Occupational heat exposure is associated with substantial morbidity and mortality among outdoor workers. We sought to descriptively evaluate spatiotemporal variability in heat threshold exceedances and describe potential impacts of these exposures for crop and construction workers. We also present general considerations for approaching heat policy-relevant analyses. We analyzed county-level 2011–2020 monthly employment (Bureau of Labor Statistics Quarterly Census of Employment and Wages) and environmental exposure (Parameter-elevation Relationships on Independent Slopes Model (PRISM)) data for Washington State (WA), USA, crop (North American Industry Classification System (NAICS) 111 and 1151) and construction (NAICS 23) sectors. Days exceeding maximum daily temperature thresholds, averaged per county, were linked with employment estimates to generate employment days of exceedances. We found spatiotemporal variability in WA temperature threshold exceedances and crop and construction employment. Maximum temperature exceedances peaked in July and August and were most numerous in Central WA counties. Counties with high employment and/or high numbers of threshold exceedance days, led by Yakima and King Counties, experienced the greatest total employment days of exceedances. Crop employment contributed to the largest proportion of total state-wide employment days of exceedances with Central WA counties experiencing the greatest potential workforce burden of exposure. Considerations from this analysis can help inform decision-making regarding thresholds, timing of provisions for heat rules, and tailoring of best practices in different industries and areas.
Background
Thoroughbred horse farm workers self‐report a high frequency of work‐related injuries and pain. However, an analysis of Thoroughbred horse farm workers’ compensation injury claims is absent from the literature, yet may benefit worker safety.
Methods
We analyzed workers’ compensation insurance firm data containing 2276 claims filed between 2008 and 2015. Injury frequency, cost, and lost time per cause, nature, and body part injured were examined qualitatively and via univariate tests. Factors associated with high cost and high duration lost time claims were modeled via multivariable logistic regression.
Results
The average Thoroughbred worker claim cost $4,198 and accrued 10 days lost time, involving strikes (57% of total claims), sprains/strains (34%), and wrist/hand injuries (18%). Injuries primarily occurred on mornings (54%), weekdays (79%), and during the transition from breeding to sales (23%). Jobs with a high level of horse contact had significantly higher cost ($6,487) and higher duration lost time (16.8 days) claims, with significantly higher cost claims on the weekends ($6,471) and from the oldest workers ($7466), vs reference groups. Logistic models indicate significantly increased odds of a high‐cost injury among high horse contact jobs (OR = 1.87; 95% C.I. = 1.53‐2.29) and older age tertiles (1.38; 1.08‐1.75; 1.70, 1.32‐2.18). The odds of a high duration lost time injury are significantly increased among high horse contact jobs (1.91; 1.53‐2.39) and males (1.50, 1.13‐1.98), with significantly reduced odds among the most tenured workers (0.74; 0.56‐0.99).
Conclusions
Our findings elucidate factors to reduce injury frequency, cost, and lost time among Thoroughbred horse farm workers.
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