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Abstract
The yellow mealworm, Tenebrio molitor L. (Coleoptera: Tenebrionidae), is one of the few edible insects commercially produced around the globe as alternative protein sources for food and feed. Temperature and nutrition are the two most influential environmental determinants of growth and development in insects, but little is known about their combined effects in T. molitor. Here we examined how temperature and dietary protein:carbohydrate (P:C) balance act in concert to influence key performance traits in T. moltior larvae reared on one of the 36 treatment combinations of six temperatures (19, 22, 25, 28, 31, and 34 °C) and six protein:carbohydrate ratios (P:C = 1:5, 1:2, 1:1, 2:1, 5:1, and 1:0). Apart from females accumulating higher lipid content than males, there were no sex differences in all measured traits. Survivorship was high at low temperatures (<25 °C) and high P:C ratios (>1:1), but decreased with increasing temperature and decreasing P:C ratio. An increase in temperature accelerated development but resulted in reduced pupal mass. Thermal optimum for pupal mass (19.3 °C) was thus much lower than that for development time (28.1 °C). Growth rate peaked at 27.9 °C and P:C 1.65:1 and decreased as both temperature and P:C ratio deviated from their optimum. All four key performance traits (survivorship, development time, pupal mass, and growth rate) were expressed at high levels and, hence, optimized at temperatures between 25.7 °C and 27.4 °C and P:C ratios between 1.17:1 and 2.94:1. Food consumption rate was the highest at a high P:C ratio of 8.4:1, whereas post-ingestive food utilization was the most efficient at a moderate P:C ratio of 1:1.27. The rate and efficiency of food processing were optimized at temperatures between 24.5 °C and 29.9 °C and P:C ratios between 1:1.01 and 3.98:1. Our results have implications for improving the production and nutritional value of T. molitor larvae.
The black soldier fly (BSF), Hermetia illucens (Diptera: Stratiomyidae), has become one of the most economically important insects that can be a sustainable replacement for traditional feed for swine, poultry, and aquaculture. Despite its emerging importance, studies examining the nutritional requirement of BSF have been scarce. Here we used nutritional geometry approach to determine the separate and combined effects of dietary protein and carbohydrate content on multiple life-history traits and body composition linked to fitness in BSF. BSF larvae were reared on one of 32 chemically defined diets that varied in protein-to-carbohydrate ratio (P:C=1:16, 1:8, 1:4, 1:2, 1:1, 2:1, 4:1, or 8:1) and in protein plus carbohydrate concentration (P+C=60, 120, 180, or 240 g/l). Females developed more slowly into larger adults than males, but two sexes responded to dietary variation in protein and carbohydrate in a similar manner. The topography of the nutritional performance landscapes mapped for all measured traits differed significantly from one another, with the optimal P:C ratio being 1:1.71 for preadult survivorship, 1:1.56 – 1:1.11 for development time, 1:3.36 – 1:3.16 for body weight at adult emergence, and 1:1.83 – 1:1.40 for growth rate. Significant divergence in nutritional optima among these components of fitness indicates that the occurrence of fundamental life-history trade-off can be mediated by macronutrient intake. The index representing the preadult performance of BSF had a nonlinear relationship with dietary protein, with the peak centred at the intermediate P:C ratios of 1:1.43 – 1:1.37. The optimal P:C ratio was 1:2.12 – 1:1.70 for lean body weight and 1:14.14 – 1:10.82 for lipid content. Our results highlight the importance of the balanced composition of dietary protein and carbohydrate for optimising BSF performance and have implications for enhancing the mass production of this beneficial species.
The vaginal microbiota is a determinant for the risk of preterm birth (PTB). Dominance of the vaginal niche by Lactobacillus crispatus associates with term delivery. This is the first observational clinical study of live vaginal biotherapeutics (Lactobacillus crispatus CTV-05 (LACTIN-V)) in pregnant women at high-risk of PTB. The primary aim was to explore safety, tolerability and acceptability of LACTIN-V in pregnancy. Women were offered a course of LACTIN-V at 14 weeks gestation for five consecutive days followed by weekly administration for six weeks. Participants were followed up at 15, 18-, 20-, 28- and 36-weeks’ gestation and at delivery for assessment of adverse events, compliance and tolerability. Participants completed a questionnaire to gauge experience and acceptability. In total, 73 women were recruited, of whom eight withdrew, leaving a final cohort size of 61. Self-reported compliance to the course was high (56/60, 93%). Solicited adverse events were reported in 13 women (19%) including changes in vaginal discharge, odour, colour or consistency of urine, itching and vaginal bleeding. One unsolicited adverse event was reported as haematuria at 38 weeks gestation, but was judged to be unrelated to LACTIN-V. No serious adverse events occurred. One mild adverse event led to study withdrawal. Thirty-one women completed an experience and acceptability questionnaire. Women found LACTIN-V easy and comfortable to use and the majority (30/31, 97%) would use LACTIN-V in future pregnancies. Eight women (8/31, 26%) found the schedule of use difficult to remember. The rate of PTB <34 weeks in this cohort was 3.3% compared to 7% in a historical cohort of 2,190 women at similar background PTB risk. With satisfactory uptake and good compliance, we demonstrate that LACTIN-V is safe and accepted in pregnancy, with high tolerability. Further studies are needed to assess colonisation of Lactobacillus crispatus CTV-05 and clinical efficacy.
The oral administration of Enterococcus faecium EF1 to new-born suckling and weaning piglets along with their growth performances and intestinal microbiota was investigated in this study. Twenty-four new-born piglets were initially divided into 2 groups. The probiotics group received 2 ml of 10% sterilised skimmed milk by oral gavage supplemented with 6×108 cfu/ml viable E. faecium EF1 at the first, the third and the fifth day after birth, while the control group received 2 ml of 10% sterilised skimmed milk without probiotics at the same time. Results showed that oral administration of E. faecium EF1 was associated with a remarkable increase on the body weight of piglets for both suckling and weaning periods, by 30.73% (P<0.01) and 320.84% (P<0.01), and also decreased the diarrhoea rate, by 43.21% (P<0.05) and 71.42% (P<0.05), respectively. In addition, 454-pyrosequencing analysis revealed that there was no significant difference in the intestinal microbial diversity of the suckling piglets between the two groups; nevertheless, when compared to the control group, the relative abundance of Firmicutes in the probiotics group was substantially augmented, while the relative abundance of Proteobacteria, Bacteroidetes and Fusobacteria diminished. However, results indicated that oral administration of E. faecium EF1 did not have any influence on the relative abundance of Firmicutes in weaning piglets rather than increasing the relative abundance of Bacteroidetes and decreasing the relative abundance of Proteobacteria. Furthermore, at the level of the Firmicutes phylum, the relative abundance of Lactobacillales in the probiotic group increased significantly. These findings suggest that oral administration of E. faecium EF1 to new-born piglets could improve the growth performance and intestinal microbiota of piglets for both suckling and weaning periods.
Leaf colour, size and toughness were investigated in five plant species important in the diet of Macaca fascicularis in Singapore. Leaf colour and size were examined as potential visual cues for food selection, whereas toughness mirrored fibre content, the inverse of food quality. As leaves matured, they changed colour and toughened. Leaf lightness and yellowness were strongly negatively correlated with toughness, but variation in both the red-green axis of the CIE Lab colour space and leaf size were not. Leaves selected as food by the macaques were distinguished by being very light, yellow to slightly green. Some leaves were dappled with red. The literature suggests that these leaves are relatively rich in protein without being tough and therefore would be sought after by primates. We argue that leaf colour is an important indicator of the nutritive value of leaves. Trichromatic vision is an important advantage in finding those palatable leaves that are dappled red. These would appear dark to dichromatic primates and be deceptive by making leaves look older (lower in quality) than they actually are. This would decrease the perceived window of feeding opportunity for such primates who would be at a disadvantage in trying to find these leaves. It is possible that trichromatic vision in catarrhine primates may have originally evolved for the detection of red coloration in the leaves of shade-tolerant tropical plants, enabling the better exploitation of a food resource.
The establishment of efficient and sustainable production of industrially important insects necessitates the detailed knowledge of the optimal mixture of macronutrients required for maximising their performance and fitness. The white spotted flower chafer, Protaetia brevitarsis (Coleoptera: Scarabaeidae: Cetoniinae), is one of the most important edible insects in East Asia with high nutritional and medicinal value. Here, we report how the ratio of protein to digestible carbohydrate (P:C) in the diet influenced lifespan and reproductive performance in the adults of P. brevitarsis. Throughout their lifespan, beetles were fed ad libitum one of five diets with differing P:C ratio (0:1, 3:7, 1:1, 7:3, 1:0). Both lifespan and the number of eggs produced over the lifetime were maximised at the P:C ratio of 3:7 and declined as the ratio deviated away from this optimal P:C composition. Beetles fed a diet containing only protein (P:C 1:0) not only had the shortest lifespan but also exhibited substantially reduced lifetime egg production compared to those fed the other diets. However, the effects of dietary P:C ratio on daily egg production rate and egg hatchability were marginal. The number of eggs produced at each age stage peaked at the age of week 2 and then gradually declined with increasing age, showing the sign of reproductive senescence. Age-specific egg production was higher in beetles confined to three intermediate P:C ratios (3:7, 1:1, 7:3) than those confined to two extreme P:C ratios (0:1, 1:0) throughout their lifespan. The speed of age-related decrease in reproductive performance was the slowest at P:C 3:7. Our data have implications for optimising the production of this edible insect with emerging economic importance.
An outline is given for a field kit aiming to substantially increase the in situ knowledge gleaned from feeding studies of primates. Measurements are made of colouration (spectrum of non-specular reflection) and many mechanical, chemical and spatial properties of primate foods.