Winter diets of round whitefish Prosopium cylindraceum in the St. Marys River

The round whitefish (Prosopium cylindraceum) is a coregonine native to numerous northern temperate lentic and lotic systems across North America. The St. Marys River, located between the United States and Canadian border, is one such system where the round whitefish supports a recreational fishery and is a prey source for piscivores. Round whitefish are generally known to prey upon benthic macroinvertebrates, but diets of round whitefish in the St. Marys River have not been characterized. We analyzed stomach contents from 107 round whitefish sampled from the St. Marys River during the winter months of 2020 and 2021 to describe their diets, examine their feeding strategies, and determine if they fed selectively. Ephemeropterans were the most important prey numerically, followed by megalopterans, trichopterans, and dipterans. The round whitefish population sampled from the St. Marys River exhibited a specialized feeding strategy that most often specialized on ephemeropterans. Patterns in the importance of prey types and feeding strategy were consistent between both years sampled. Selective feeding by round whitefish was examined using diet and environmental data from 2021 only, and we found that round whitefish selected both ephemeropterans and megalopterans, but avoided trichopterans and dipterans. Rather than being opportunistic invertivores, our results indicate round whitefish are specialized and selective feeders. Our findings can be used to inform conservation and management of round whitefish, as diets represent an integration of multiple ecological components such as prey availability, predator behavior, and habitat quality.     

Different diets affecting biology and digestive physiology of the Khapra beetle,Trogoderma granarium Everts (Coleoptera: Dermestidae)

The Khapra beetle, Trogoderma granarium Everts (Coleoptera: Dermestidae), is a serious pest of grain and other stored products through the world. In this research, effect of five host diets including barley, rice, rye, wheat and walnut was studied on some of biological traits, nutritional indices and digestive enzymatic activity of T. granarium at 33 ± 1 °C, 65 ± 5% RH and a photoperiod of 14:10 (L:D) h. The Khapra beetle larvae reared on walnut had the highest number of larval instar and longest duration of larval and pupal stages (91.30 ± 0.4 days). The heaviest pupal weight of T. granarium was on rye (4.22 ± 0.01 mg) and the lightest weight was on rice (3.99 ± 0.01 mg) and walnut (4.00 ± 0.01 mg). The highest realized fecundity and fertility were recorded for the females reared on rye (45.88 ± 1.08 eggs/female and 69.39 ± 0.68%, respectively) and wheat (49.02 ± 1.55 eggs/female and 67.54 ± 0.69%, respectively), and the lowest ones were observed for the females came from larvae fed walnut (15.45 ± 0.71 eggs/female and 34.55 ± 0.82%, respectively). Also, the results showed that T. granarium larvae reared on walnut had the lowest values of the efficiency of conversion of ingested food (7.67 ± 0.04%) and relative growth rate (0.044 ± 0.0002 mg/mg/day). The lowest midgut amylolytic (0.044 ± 0.0005 and 0.047 ± 0.0005 mU/individual, respectively) and proteolytic (0.015 ± 0.0004 and 0.016 ± 0.0001 mU/individual, respectively) activity of the sixth instar was detected on walnut and rice. The highest inhibition of amylase (53.37 ± 0.75%) and protease activity (48.54 ± 0.96%) was estimated by incubating midgut extracts from the last instars with wheat and barley proteinaceous extracts, respectively. The results indicated that walnut was the most unsuitable diet for feeding and development of T. granarium.     

Effects of developmental stage,cold acclimation and diet on the cold tolerance of three species of Cryptolestes (Coleoptera: Laemophloeidae)

Flat grain beetles (Coleoptera: Laemophloeidae) are common stored-product insect pests in Canada, infesting cereals in grain bins, equipment and end products in flour mills. We studied the cold tolerance of the three most common flat grain beetles: Cryptolestes ferrugineus, Cryptolestes turcicus and Cryptolestes pusillus, by measuring the survival at −10 °C and supercooling point (SCP) for different life stages (egg, young larva, old larva, pupa and adult) reared on flour mixed with brewer’s yeast. Probit analysis was used to estimate the lethal time for 50 and 95% mortality. This was done with non-acclimated individuals (only held at 30 °C) or cold-acclimated individuals (held at 18, 10 and 5 °C, for 1 week/temperature). In general, adults were the most cold-hardy stage for each of the species. Acclimated insects were anywhere from no increase in cold tolerance to 14-fold more cold-tolerant than the corresponding non-acclimated stage and species. Cryptolestes ferrugineus was most cold-tolerant species (58 d at −10 °C to reach 95% mortality for acclimated adult), C. turcicus was the next most cold-tolerant, (39 d) and C. pusillus was the least cold-tolerant (11 d). The cold tolerance of adults reared on three diets was measured both for acclimated and non-acclimated insects. The adults reared on grain diet (whole wheat kernels, cracked wheat kernels and wheat germ (90:5:5 mass ratio) were the most cold-tolerant, adults reared on white-wheat flour and brewer’s yeast diet (95:5 mass ratio) had the next highest cold tolerance followed by the adults reared on 100% white-wheat flour. Supercooling point (SCP) of insects ranged from −20.6 to −26.7 °C. In general, acclimated insects had slightly lower SCP than non-acclimated insects.     

Diet composition and overlap for adult walleye,lake whitefish,and yellow perch in Green Bay,Lake Michigan

Interspecific interactions among walleye Sander vitreus, lake whitefish Coregonus clupeaformis, and yellow perch Perca flavescens in Green Bay could influence the population status of each species, but potential trophic interactions are poorly understood. Our objectives were to determine if diet assemblages for each species and diet overlap among species varied spatially and temporally within Green Bay. Adult walleye (≥381 mm total length (TL); N = 981), lake whitefish (≥432 mm TL; N = 1507), and yellow perch (≥150 mm TL; N = 1174) were collected during May-October of 2018 and 2019 from multiple locations in southern and northern Green Bay. Diet assemblages of each species varied between northern and southern Green Bay, but walleye diets were more temporally variable (among months within zones and between years) than diets of lake whitefish or yellow perch. Lake whitefish represented a seasonally important prey item for walleye in southern Green Bay, composing 10 % and 41 % of walleye diets by weight in May and June, respectively. Yellow perch generally composed <15 % of walleye diets by weight but were consumed at a broader spatiotemporal scale than lake whitefish. Diet overlap between walleye and both lake whitefish and yellow perch was generally weak or moderate, whereas diet overlap between whitefish and perch was generally strong. Our assessment of adult trophic interactions suggests that changes in the population status of one species could influence fisheries for all three, and we identify additional research questions to address potential population-level effects of these trophic interactions.     

Accumulation of cadmium in livers and kidneys in Greenlanders

In the Arctic, the traditional diet exposes its people to a very high intake of cadmium because it is highly concentrated in the liver and kidneys of commonly eaten marine mammals. In one study in Greenland, the cadmium intake was estimated to 182 microg/day/person in the fall and 346 in the spring. To determine whether the cadmium is accumulated in humans, we analyzed autopsy samples of liver and kidneys from 95 ethnic Greenlanders (aged 19-89) who died from a wide range of causes. The cadmium concentration in liver (overall mean 1.97 microg/g wet wt) appeared to be unrelated to any particular age group, whereas the concentrations in the kidneys peaked in Greenlanders between 40 and 50 years of age (peak concentration 22.3 microg/g wet wt). Despite the high cadmium levels in the typical Greenlander diet, we found that the cadmium concentrations in livers and kidneys were comparable to those reported from Denmark, Sweden, Australia and Great Britain. Furthermore, even though the mean cadmium intake from the diet was estimated to be 13-25 times higher in Greenlanders than in Danes, we found similar cadmium levels in the kidneys of both. Seal livers and kidneys are the main source of cadmium in the diet of Greenlanders, but these tissues are not eaten in Denmark. Thus, our results suggest that the accumulation of cadmium from Greenlander's marine diet is very low.     

Use of Automated Self-administered 24-hour Recalls (ASA24-2011) and Diet Quality Scores to Characterize Women who Met or Exceeded Weight Gain Recommendations during Pregnancy

Understanding dietary patterns of women who exceed gestational weight gain (GWG) recommendations is crucial to promote healthier pregnancies. This study assessed nutrient intake, diet quality and GWG of participants in the Pregnancy, Exercise, and Nutrition (PEN) feasibility study who met or exceeded weight gain recommendations during pregnancy. The ASA24-2011, a web-based tool, was used to collect dietary intake data and dietary quality was assessed with the Healthy Eating Index (HEI)-2010 and the Diet Quality Index-Pregnancy (DQI-P). Fifty-three percent of PEN participants exceeded the 2009 IOM GWG recommendations; no significant associations were found between reported dietary quality and gestational weight gain.     

#Gettinghealthy: The perceived influence of social media on young adult health behaviors

Young adults (18–25 years old) spend a majority of their waking hours with technology and young adulthood is an important developmental time period for establishing lasting health behaviors. Considering the relevance of technology and health during young adulthood the current study explored young adults (N = 34) perceptions of social media’s (e.g., social networking) influence on their health behaviors (i.e., diet and exercise) using a social ecological framework. Data was collected through eight focus groups and four individual interviews. Three themes were identified through phenomenological qualitative analysis. Young adults perceived that technology could be both a barrier and a motivator for exercise. Social media was also credited with expanding food choices through creating access to a variety of recipes, providing a venue for showcasing the food young adults eat or prepare, and distracting young adults from making positive food choices. Participants also reported that it is common to post statuses or pictures relating to exercise practices on social media during young adulthood. Young adults indicated that these posts could be inspirational or misused, depending on the context. Results are discussed in terms of theory and preliminary implications.     

An NMR-based metabolomic assessment of cultured cobia health in response to dietary manipulation

Commercial aquaculture feeds rely heavily on fishmeal and fish oil, which can be expensive and ecologically unsustainable. To evaluate the efficacy of reduced fishmeal diets for outgrowth, a dietary study was conducted on the finfish cobia, Rachycentron canadum. NMR-based metabolomic techniques were used to assess the effect of decreasing dietary fishmeal on the health of the cobia. Filtered serum ¹H NMR spectra analysed by principal components analysis (PCA) showed cobia fed reduced fishmeal diets were metabolically different than cobia on control diets. In particular, tyrosine and betaine increased in cobia fed reduced fishmeal diets while glucose decreased, suggesting that these cobia were not receiving the necessary nutritional components required for energy and growth. The formulated control diet contributed to enriched growth and significantly elevated lactate levels suggesting enhanced gut microflora metabolism in response to dietary components. The results show that NMR-based metabolomic analysis is a useful tool in aquaculture studies.