The Survival and Physiological Response of Calliptamus abbreviatus Ikonn (Orthoptera: Acrididae) to Flavonoids Rutin and Quercetin

Insect-resistant substances from plants are important natural resources that human beings can potentially develop and use to control pests. In this study, we explored the adverse effects of rutin and quercetin on grasshopper (Calliptamus abbreviatus), as well as the insect's physiological response to these substances in laboratory and field experiments. These two plant compounds exhibited toxic effects on C. abbreviatus, with quercetin showing a stronger toxicity, indicated by a lower survival, slower development, and higher induced gene expression and activities of UDP-glucuronosyltransferase, cytochrome P450s, superoxide dismutase, peroxidase and catalase, compared to rutin. These compounds, especially quercetin, have the potential to be developed as biopesticides to control grasshoppers.

Rapid Dietary Shift in Podarcis siculus Resulted in Localized Changes in Gut Function

AbstractNatural dietary shifts offer the opportunity to address the nutritional physiological characters required to thrive on a particular diet. Here, we studied the nutritional physiology of Podarcis siculus, with populations on Pod Mrčaru, Croatia, that have become omnivorous and morphologically distinct (including the development of valves in the hindgut) from their insectivorous source population on Pod Kopište. We compared gut structure and function between the two island populations of this lizard species and contrasted them with an insectivorous mainland out-group population in Zagreb. On the basis of the adaptive modulation hypothesis, we predicted changes in gut size and structure, digestive enzyme activities, microbial fermentation products (short-chain fatty acids [SCFAs]), and plant material digestibility concomitant with this dietary change. The Pod Mrčaru population had heavier guts than the mainland population, but there were no other differences in gut structure. Most of the enzymatic differences we detected were between the island populations and the out-group population. The Pod Mrčaru lizards had higher amylase and trehalase activities in their hindguts compared with the Pod Kopište population, and the Pod Kopište lizards had greater SCFA concentrations in their hindguts than the omnivorous Pod Mrčaru population. Interestingly, the differences between the Pod Mrčaru and Pod Kopište populations are primarily localized to the hindgut and are likely influenced by microbial communities and a higher food intake by the Pod Mrčaru lizards. Although subtle, the changes in hindgut digestive physiology impact the digestibility of plant material in adult lizards-Pod Mrčaru lizards had higher digestibility of herbivorous and omnivorous diets fed over several weeks in the laboratory than did their source population.

Phenotypic and Transcriptomic Response of the Grasshopper Oedaleus asiaticus (Orthoptera: Acrididae) to Toxic Rutin

Rutin, a widely distributed phytochemical flavonoid, can be used to control insect pests. In this study, we studied the growth performance of the grasshopper Oedaleus asiaticus Bey-Bienko given xenobiotic rutin using feeding experiments and transcriptomic analysis. O. asiaticus had reduced body size, lower survival rate, and reduced growth performance when fed with xenobiotic rutin. Rutin-fed nymphs had large variation in gene expression profiles, with a total of 308 genes significantly upregulated and 287 genes downregulated. The upregulated genes were significantly enriched in stress resistance-, immune-, and detoxification-related biological processes and the Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways. Downregulated genes mainly involved cuticle biosynthesis and nutrition metabolism-related pathways. The quantitative real-time PCR (qRT-PCR) analysis of 15 candidate genes also produced results consistent with the transcriptome data. These results suggested that grasshoppers’ capacity for biosynthesis and nutrition metabolism decreased, and stress resistance and metabolized capacity to toxic substances were significantly induced when O. asiaticus was fed on xenobiotic rutin. Rutin, as a phytotoxin, had detrimental effects and induced changes in gene expression profiles for O. asiaticus. This study can provide a molecular basis and offer future opportunities for the development of rutin-related insecticides and their application to grasshopper control.

Links between Natural Variation in the Microbiome and Host Fitness in Wild Mammals

Recent studies in model organisms have shown that compositional variation in the microbiome can affect a variety of host phenotypes including those related to digestion, development, immunity, and behavior. Natural variation in the microbiome within and between natural populations and species may also affect host phenotypes and thus fitness in the wild. Here, I review recent evidence that compositional variation in the microbiome may affect host phenotypes and fitness in wild mammals. Studies over the last decade indicate that natural variation in the mammalian microbiome may be important in the assistance of energy uptake from different diet types, detoxification of plant secondary compounds, protection from pathogens, chemical communication, and behavior. I discuss the importance of combining both field observations and manipulative experiments in a single system to fully characterize the functions and fitness effects of the microbiome. Finally, I discuss the evolutionary consequences of mammal-microbiome associations by proposing a framework to test how natural selection on hosts is mediated by the microbiome.

Nutritional and Health-Related Effects of a Diet Containing Apple Seed Meal in Rats: The Case of Amygdalin

Apple pomace includes seeds that are rich in protein, fiber, and oil, which can be extracted from them. However, they can also contain a significant amount of toxigenic amygdalin. We hypothesized that amygdalin is a compound that significantly reduces the nutritional and health quality of defatted apple seeds. An experiment was conducted on rats that were distributed into three groups and fed with high-fructose diets. In the control (C) and amygdalin (AMG) groups, cellulose and casein were the source of dietary fiber and protein, respectively; in the apple seed meal (ASM) group, dietary fiber and protein originated from the endosperm of apple seeds, which were previously defatted and ground. A diet fed to the ASM group also contained 0.24% of amygdalin from the meal, whereas the AMG diet was supplemented with the same amount of synthetic amygdalin. After 14 days of experimental feeding, the body weight of rats was decreased in the ASM group. When compared to the C group, apparent protein digestibility and nitrogen retention were increased in the AMG group, while both were decreased in the ASM group. In the small intestine, mucosal maltase activity was decreased in the AMG and ASM groups, whereas lactase activity was only decreased by dietary amygdalin. The caecal SCFA pool and butyrate concentration were significantly increased in the ASM group compared to the other groups. Moreover, the ASM diet increased plasma concentration of high density lipoprotein (HDL) cholesterol and plasma antioxidant capacity of water-soluble substances (ACW). It also decreased the liver content of thiobarbituric acid-reactive substances (TBARS). In contrast, dietary amygdalin did not affect these indices. Dietary supplementation with apple seed meal can exert beneficial effects on the intestinal tract, blood lipid profile and antioxidant status of rats. In most cases, these effects are not limited by the presence of amygdalin. However, the nutritional value of protein from apple seed meal is relatively low.