Unusual Diets Research Articles

Cues of uncommon food habits within dung beetles: Notes from a seasonally dry tropical forest in South America

The assessment of species’ diet and trophic plasticity serve as key elements to understand their adaptations to harsh ecosystems, such as deserts and dry forests. Among dung beetles, coprophagy is the main feeding habit, which may be substituted or complemented by other unusual diets, such as granivory and necrophagy. This study presents new records of dung beetle uncommon diets in Caatinga, the largest Seasonally Dry Tropical Forest in America. We include novel descriptions of the genera Dichotomius Hope, 1838 and Canthidium Erichson, 1847 in using and removing seeds in Caatinga. We also present the first report of dung beetles from Caatinga attracted to dead millipedes, specifically for Coprophanaeus pertyi (Olsufieff, 1924). Also, we found goat hairballs along with the roller beetle Deltochilum verruciferum Felsche, 1911 inside a pitfall trap, suggesting that this species may use animal fur to feed or breed. Finally, we included an updated list on unusual food records of dung beetle species in Caatinga dry forest. Our findings indicate that dung beetles in Caatinga display diverse feeding habits in response to extreme environmental conditions and/or limited resources. We expand the still-scarce knowledge regarding dung beetle feeding ecology outside their interaction with dung or the soft tissues of carrion. Despite our findings, new evidence is essential to reinforce our understanding on trophic plasticity of dung beetles in Caatinga. A better comprehension of resource plasticity by dung beetles will also be a significant input for biodiversity conservation due to the changes in food availability in anthropogenic landscapes.

Anatomical shifts linked with unusual diets in deep-sea snails.

Anatomical shifts linked with unusual diets in deep-sea snails.

Genomic analysis of novel Yarrowia-like yeast symbionts associated with the carrion-feeding burying beetle Nicrophorus vespilloides

BackgroundMutualistic interactions with microbes can help insects adapt to extreme environments and unusual diets. An intriguing example is the burying beetle Nicrophorus vespilloides, which feeds and reproduces on small vertebrate carcasses. Its fungal microbiome is dominated by yeasts that potentially facilitate carcass utilization by producing digestive enzymes, eliminating cadaver-associated toxic volatiles (that would otherwise attract competitors), and releasing antimicrobials to sanitize the microenvironment. Some of these yeasts are closely related to the biotechnologically important species Yarrowia lipolytica.ResultsTo investigate the roles of these Yarrowia-like yeast (YLY) strains in more detail, we selected five strains from two different phylogenetic clades for third-generation sequencing and genome analysis. The first clade, represented by strain B02, has a 20-Mb genome containing ~ 6400 predicted protein-coding genes. The second clade, represented by strain C11, has a 25-Mb genome containing ~ 6300 predicted protein-coding genes, and extensive intraspecific variability within the ITS–D1/D2 rDNA region commonly used for species assignments. Phenotypic microarray analysis revealed that both YLY strains were able to utilize a diverse range of carbon and nitrogen sources (including microbial metabolites associated with putrefaction), and can grow in environments with extreme pH and salt concentrations.ConclusionsThe genomic characterization of five yeast strains isolated from N. vespilloides resulted in the identification of strains potentially representing new YLY species. Given their abundance in the beetle hindgut, and dominant growth on beetle-prepared carcasses, the analysis of these strains has revealed the genetic basis of a potential symbiotic relationship between yeasts and burying beetles that facilitates carcass digestion and preservation.

Larvae of the Clothing Moth Tineola bisselliella Maintain Gut Bacteria that Secrete Enzyme Cocktails to Facilitate the Digestion of Keratin.

The evolutionary success of insects is promoted by their association with beneficial microbes that enable the utilization of unusual diets. The synanthropic clothing moth Tineola bisselliella provides an intriguing example of this phenomenon. The caterpillars of this species have adapted to feed on keratin-rich diets such as feathers and wool, which cannot be digested by most other animals and are resistant to common digestive enzymes. Inspired by the hypothesis that this ability may be conferred by symbiotic microbes, we utilized a simple assay to detect keratinase activity and a method to screen gut bacteria for candidate enzymes, which were isolated from feather-fed larvae. The isolation of DNA from keratin-degrading bacterial strains followed by de novo genome sequencing resulted in the identification of a novel bacterial strain related to Bacillus sp. FDAARGOS_235. Genome annotation identified 20 genes with keratinase domains. Proteomic analysis of the culture supernatant from this gut bacterium grown in non-nutrient buffer supplemented with feathers revealed several candidate enzymes potentially responsible for keratin degradation, including a thiol-disulfide oxidoreductase and multiple proteases. Our results suggest that the unusual diet of T. bisselliella larvae promotes their association with keratinolytic microorganisms and that the ability of larvae to feed on keratin can at least partially be attributed to bacteria that produce a cocktail of keratin-degrading enzymes.

Nutritional immunology: Diversification and diet-dependent expression of antimicrobial peptides in the black soldier fly Hermetia illucens

The black soldier fly Hermetia illucens is used for the bioconversion of organic waste into feed for livestock and aquaculture, and is economically among the most important farmed insects in the world. The larvae can be fed on agricultural waste and even liquid manure, resulting in highly unpredictable pathogen levels and dietary conditions. Here we show that H. illucens larvae express a remarkably expanded spectrum of antimicrobial peptides (AMPs), many of which are induced by feeding on a diet containing high bacterial loads. The addition of sulfonated lignin, cellulose, chitin, brewer's grains or sunflower oil revealed the diet-dependent expression profiles of AMPs in the larvae. The highest number of AMPs and the highest levels of AMP expression were induced by feeding larvae on diets supplemented with protein or sunflower oil. Strikingly, the diet-dependent expression of AMPs translated into diet-dependent profiles of inhibitory activities against a spectrum of bacteria, providing an intriguing example for the emerging field of nutritional immunology. We postulate that the fine-tuned expression of the expanded AMP repertoire mediates the adaptation of the gut microbiota to the digestion of unusual diets, and this feature could facilitate the use of H. illucens for the bioconversion of organic waste.

COMPETITIVE RELEASE IN DIETS OF OCELOT (LEOPARDUS PARDALIS) AND PUMA (PUMA CONCOLOR) AFTER JAGUAR (PANTHERA ONCA) DECLINE

We used fecal analyses to document the diet of ocelots (Leopardus pardalis) and puma (Puma concolor) at 2 sites in central Panama. We detected puma on Barro Colorado Island (BCI) nearly every month during the study but never found evidence of jaguars (Panthera onca) at either site. Both ocelots and puma fed predominantly on mammalian prey, but consumed a diversity of species. Collared peccaries (Pecari tajacu) and Central American red brocket (Mazama temama) were the most important food items for puma, whereas Central American agoutis (Dasyprocta punctata) and sloths (Choloepus hoffmanni and Bradypus variegatus) were the most important for ocelots. Considerable overlap in diet was found between populations and species, but the diet of puma on BCI was significantly different from the 2 ocelot populations in containing more large prey, suggesting that dietary differences between these predator species are chiefly related to their relative body size. Comparing across larger scales, both populations of ocelots in our study ate larger prey than elsewhere in their range, suggesting that their fundamental niche includes more medium-sized prey than their realized niche in other sites. Puma on BCI ate proportionally more peccaries and deer than in most other populations. These unusual diets in the wake of a recent decline or local extinction of jaguars are consistent with a prey shift in response to competitive release.

The Mind Matters

Some years ago, a study by Gill and associates1 regarding the use of alternative medicine among diabetic patients in the United Kingdom led the authors to conclude that there is cause for concern: insulin-dependent patients were found to have reduced or even stopped taking their insulin in favor of therapeutic approaches including prayer, faith healing, unusual diets, and supplements of vitamins and trace elements. The authors could understand that diabetic patients could experience their treatment as “somewhat unsatisfactory” and therefore seek alternative treatments making more attractive claims. A survey conducted in the United States by Astin,2 however, has shown that dissatisfaction with conventional medicine is not the main motive for using alternative medicine. Rather, most alternative-medicine users appear to be doing so because they find these health care alternatives to be more congruent with their own values, beliefs, and philosophical orientations toward health and life. Interestingly, many of the therapies commonly labeled as “alternative” in fact are psychological techniques, e.g., relaxation and hypnosis, and apparently there is a growing market for professionals in the field of “mind-body interventions.”3 As a psychologist trained in health psychology and behavioral medicine, I question whether applications of such psychological techniques …

Carrot Addiction

A case report of carrot addiction is presented with a review of the literature and comment on the role of beta carotene in addictive behaviour. The addiction occurred in a 49-year-old woman under conditions of stress due to marital problems, leading to a depressive illness and increased smoking. The patient maintained that the sensations of carrot craving and withdrawal were quite distinct from those associated with smoking. The patient was advised to record her daily carrot consumption. The patient did not return for several months, but stopped eating carrots after an operation, at which time she also stopped smoking. Compusive carrot eating, regarded as a rare condition, has received scant documentation, unlike hypercarotenemia due to unusual diets or food fads. Nervousness, craving, insomnia, waterbrash and irritability are associated with withdrawal from excessive carrot eating. The basis for the addiction is believed to be beta carotene, found in carrots. Does carrot eating, an aggressively oral activity, merely act as a behavioural substitute for smoking? Or does beta carotene contain a chemical element that replicates the addictive component of nicotine? Further study of this unusual but intriguing addiction may reveal more about the basis of all addictions, with particular implications for the cessation of cigarette smoking.

Interaction of Dietary Protein with Cellulose in the Adaptation to Caloric Dilution by Weanling Rats

The adaptive response of food intake to increasing levels of dietary cellulose was studied in weanling rats fed limiting amounts of dietary protein of different qualities. At low levels of dietary cellulose, the food intake depends on protein quality. As the cellulose levels were increased, the diet and gross energy digestibilities diminished, yielding diets with lower digestible energy contents. The rats fed the higher quality protein were able to compensate for this caloric dilution, increasing their food consumption enough to keep constant their digestible energy intake. The animals fed a lower quality protein, however, were unable to make this adaptive increase in food intake. As a result, although gross food intake remained stable, cellulose constituted an increasing proportion of it and the digestible energy consumption of these animals diminished. Water consumption in this trial appears to reflect the animal's digestible energy intake rather than cellulose consumption. The above observations may be considered as an indication that a smooth regulation of the energy intake occurs only with a complete or non-deficient diet and that deficient, abnormal or unusual diets upset this process. In the present experimental situation, when dietary protein is inadequate, the animal can no longer make appropriate compensatory increases in its food consumption to keep its digestible energy intake constant.cellulose dietary protein caloric dilution food intake

Holistic Health or Holistic Hoax?

Holistic health, a term increasingly bandied about with reserve or reverence depending on one's perspective, is an uncharted or at least fuzzy area for many physicians. Its proponents, a curious axis of faith healers, chiropractors, clergymen, and PhDs, along with MDs, RNs, DOs, and others without visible signs of qualifications, preach a message as old as the Bible and as American as apple pie: personal growth through self-actualization and maximum functioning of mind, body, and spirit. Their methods of achieving such laudable goals run the full gamut from laying on of hands and kinesiology through internal purging or external application of castor oil, to meditation, unusual diets, and some of the most recent scientific developments, including biofeedback. Holistic practitioners profess to treat the whole person, not simply disease. They claim traditional Western or scientific medicine is too disease oriented and splits mind from body. They not only integrate both but

Fast foods for adolescents. nutritional disaster or triumph of technology?

Diets eaten by children and adolescents frequently alarm and puzzle their parents, and sometimes their medical advisors as well. The periodically recurring fad diets based on occult or religious beliefs run the gamut from the bizarre and dangerous (brown rice and water) to the nutritionally acceptable. For example, the vegetarian menus, often difficult to select with the necessary precision for protein adequacy, may be nutritionally sound when properly designed. These unusual diets, which must be evaluated individually, do not compose the more general concern about adolescent eating. The heavy patronage of fast-food chains looms much larger. How do such foods compare in nutritional adequacy to the usual balanced home diet? Before one can answer such a question, one must have a means for analyzing a diet, and one must have standards of nutritional adequacy. Two inexpensive references, Agriculture Handbook No. 8 1 and Recommended Dietary Allowances , 2 belong in every