Complete nutrient composition of commercially raised invertebrates used as food for insectivores

A variety of invertebrates are commonly fed to insectivorous animals by both zoos and hobbyists, but information as to the nutrient composition of most commercially raised species is limited. Adult house crickets, house cricket nymphs (Acheta domesticus), superworms (Zophobas morio larvae), giant mealworm larvae, mealworm larvae and adult mealworms (Tenebrio molitor), waxworm larvae (Galleria mellonella), and silkworm larvae (Bombyx mori) were analyzed for moisture, crude protein, crude fat, ash, acid detergent fiber (ADF), neutral detergent fiber (NDF), minerals, amino acids, fatty acids, and vitamins. Earthworms (Lumbricus terresstris) were analyzed for moisture, crude protein, crude fat, ash, ADF, NDF, minerals, amino acids, and vitamins A and D₃. Proximate analyses were variable, with wide ranges found for moisture (57.9–83.6%), crude protein (9.3–23.7%), crude fat (1.6–24.9%), ADF (0.1–7.4%), NDF (0.0–11.5%), and ash (0.6–1.2%). Energy content ranged from a low of 674 kcal/kg for silkworms to 2,741 kcal/kg for waxworms.Using an amino acid scoring pattern for rats, the first limiting amino acid for all invertebrates tested was the total sulfur amino acid methionine+cystine. Deficiencies by nutrient (% of samples deficient vs. NRC requirements for rats on a dry matter (DM) basis) were as follows: calcium (100%), vitamin D₃ (100%), vitamin A (89%), vitamin B₁₂ (75%), thiamin (63%), vitamin E (50%), iodine (44%), manganese (22%), methionine‐cystine (22%), and sodium (11%). Deficiencies by invertebrate species (number of nutrients deficient vs. the NRC requirements for rats on a DM basis) were as follows: waxworms (9), superworms (8), giant mealworm larvae (7), adult mealworms (6), mealworm larvae (5), adult house crickets (4), house cricket nymphs (4), silkworms (4), and earthworms (4). These data provide a basis for determining nutrient intake of captive insectivores, and will aid in the development of gut‐loading diets to provide captive insectivorous animals with appropriate levels of necessary nutrients. Zoo Biol 21:269–285, 2002. © 2002 Wiley‐Liss, Inc.     

Complete nutrient content of four species of commercially available feeder insects fed enhanced diets during growth

Commercially raised feeder insects used to feed captive insectivores are a good source of many nutrients but are deficient in several key nutrients. Current methods used to supplement insects include dusting and gut‐loading. Here, we report on the nutrient composition of four species of commercially raised feeder insects fed a special diet to enhance their nutrient content. Crickets, mealworms, superworms, and waxworms were analyzed for moisture, crude protein, fat, ash, acid detergent fiber, total dietary fiber, minerals, amino acids, fatty acids, vitamins, taurine, carotenoids, inositol, and cholesterol. All four species contained enhanced levels of vitamin E and omega 3 fatty acids when compared to previously published data for these species. Crickets, superworms, and mealworms contained β‐carotene although using standard conversion factors only crickets and superworms would likely contain sufficient vitamin A activity for most species of insectivores. Waxworms did not contain any detectable β‐carotene but did contain zeaxanthin which they likely converted from dietary β‐carotene. All four species contained significant amounts of both inositol and cholesterol. Like previous reports all insects were a poor source of calcium and only superworms contained vitamin D above the limit of detection. When compared to the nutrient requirements as established by the NRC for growing rats or poultry, these species were good sources of most other nutrients although the high fat and low moisture content of both waxworms and superworms means when corrected for energy density these two species were deficient in more nutrients than crickets or mealworms. These data show the value of modifying the diet of commercially available insects as they are growing to enhance their nutrient content. They also suggest that for most insectivores properly supplemented lower fat insects such as crickets, or smaller mealworms should form the bulk of the diet. Zoo Biol. 34:554–564, 2015. © 2015 The Authors. Zoo Biology published by Wiley Periodicals, Inc.     

Endoparasites observed within invertebrates used as live food items for captive wild birds: Overview and potential risks

To monitor and evaluate potential risks to birds’ health, invertebrate species that have been used as live food items had their body contents searched for endoparasites. The contents of approximately 10,000 invertebrates were analyzed. A principal component analysis was performed to study the relationship between the presence/absence of endoparasites and the characteristics of the invertebrates. In most of them, including the species preferred by birds such as caterpillars, waxworms, mealworms, most grasshoppers, and spiders, no organism was identified. Such findings suggest a low potential for parasite transmission associated with its consumption by birds. Although they had unknown or even unlikely implications for the birds’ health, gregarines, oxyurides Leidynema sp., and digenetic trematodes Monolecithotrema sp. were found in samples from woodlice, cockroaches, and centipedes, respectively. The only avian parasites observed in this study were Heterakis gallinarum in samples from earthworms and Acuaria spiralis from woodlice. Suggestively, soil invertebrates showed a higher prevalence of endoparasites and may represent a higher potential risk in comparison to the other categories of invertebrates sampled herein. Detritivory and collected origin were also explanatory variables related to the presence of endoparasites in the current study.     

A complex Enrichment Diet improves growth and health in the endangered Wyoming toad (Bufo baxteri)

The endangered Wyoming toad (Bufo baxteri) suffers nutrition related pathologies including poor growth and feeding difficulties from squamous metaplasia. Juvenile B. baxteri were each fed three supplemented feeder diets over 22 weeks and their growth, strike rate, and ingestion success measured. Diet (1) Enrichment Diet: feeder crickets fed fish oil, spirulina, and ground turtle feed; (2) Vitamin Diet: feeder crickets dusted heavily with Reptivite^® multi-vitamin/mineral powder; and (3) Control Diet: feeder crickets dusted with calcium and Vitamin D powder. The Enrichment Diet produced faster growth in length (P<0.05) than those fed the Vitamin Diet, and at 22 weeks either the Enrichment Diet or Control Diet produced greater weight (P<0.05) than those on the Vitamin Diet. Toads fed the Vitamin Diet ingested significantly (P<0.01) less crickets (∼105 g/toad) compared with those fed the Enrichment Diet or Control Diet (∼121 g/toad). Approximately 50% of either Reptivite^® multi-vitamin/mineral or calcium/vitamin D powder was lost within 90 sec of dusting. The Enrichment Diet produced the same strike rate (∼25 strikes in 5 min.) but higher (P<0.01) IS (38.3±4.2%) than those fed the Vitamin Diet (24.2±1.8%) or Control Diet (20.1±1.5). 1) Results showed that the Enrichment Diet provided superior growth, enrichment of feeder crickets provides an attractive alternative to the use of topical powders alone, and crickets lose ∼50% of topical powders within minutes. Feeding a diet highly enriched in retinol and unsaturated fatty acids resulted in improved growth and health for young Wyoming toads. Zoo Biol 28:197–213, 2009. © 2009 Wiley-Liss, Inc.     

Proximate,vitamins A and E,and mineral composition of free‐ranging cotton mice (Peromyscus gossypinus) from St. Catherines Island,Georgia

Although rodents are an integral part of numerous carnivore diets, there is little published information regarding nutrient composition in free‐ranging mice for comparison with laboratory‐reared prey. Cotton mice (Peromyscus gossypinus, n=6) were captured on St. Catherines Island, Georgia, and analyzed for water, ash, protein, and fat content (proximate constituents), as well as minerals and the fat‐soluble vitamins A and E. The overall body composition (mean±SD: 65.8%±1.9% water, 10.9%±2.2% ash, 56.4%±4.1% protein, and 27.2%±3.9% fat) was similar to published values for adult laboratory mice (Mus domesticus). The macro‐ (Ca, K, Mg, Na, and P) and trace (Cu, Fe, Mn, and Zn) mineral levels were also similar to previously reported values for laboratory mice, and in general met or exceeded the established nutrient requirements for domestic carnivores. Vitamin E ranged from 77 to 170 IU/kg dry matter (DM) in these mice–again, similar to values previously quantified in laboratory mice. However, the vitamin A concentrations (21,947±6,893 IU/kg DM) in the free‐ranging mice were consistently and substantially lower than values reported for whole laboratory mice. To our knowledge, this is the first quantification of vitamin A in free‐ranging mice used as prey by carnivores. While other nutrients measured were similar between captive‐reared and free‐ranging mice, the current data suggest the need for further investigation of vitamin A nutrition in the development of optimal diets for carnivores in captivity. Zoo Biol 23:253–261, 2004. © 2004 Wiley‐Liss, Inc.     

An Investigation Into the Chemical Composition of Alternative Invertebrate Prey

The aim of this study was to determine the chemical composition of eight invertebrate species and evaluate their suitability as alternative prey. The species selected were rusty red cockroaches (Blatta lateralis), six‐spotted cockroaches (Eublaberus distanti), Madagascar hissing cockroaches (Gromphadorhina portentosa), fruit flies (Drosophila melanogaster), false katydids (Microcentrum rhombifolium), beetles of the mealworm (Tenebrio molitor), and superworm beetles (Zophobas morio), as well as woodlice (Porcellio scaber). Dry matter (DM), crude protein, crude fat, neutral detergent fiber, acid detergent fiber, ash, macro and trace minerals, vitamins A and E, and carotenoid concentrations were quantified. Significant differences were found between species. Crude protein content ranged from 38 to 76% DM, fat from14 to 54% DM, and ash from 2 to 8% DM. In most species, calcium:phosphorus was low (0.08–0.30:1); however, P. scaber was an exception (12:1) and might prove useful as a dietary source of calcium for insectivores. Vitamin E content was low for most species (6–16 mg/kg DM), except for D. melanogaster and M. rhombifolium (112 and 110 mg/kg DM). The retinol content, as a measure of vitamin A activity, was low in all specimens, but varied greatly among samples (0.670–886 mg/kg DM). The data presented can be used to alter diets to better suit the estimated requirements of insectivores in captivity. Future research on the topic of composition of invertebrate prey species should focus on determination of nutrient differences owing to species, developmental stage, and diet. Zoo Biol 31:40;–54, 2012. © 2011 Wiley Periodicals, Inc.     

Feed Conversion,Survival and Development,and Composition of Four Insect Species on Diets Composed of Food By-Products

A large part of the environmental impact of animal production systems is due to the production of feed. Insects are suggested to efficiently convert feed to body mass and might therefore form a more sustainable food and/or feed source. Four diets were composed from by-products of food manufacturing and formulated such as to vary in protein and fat content. These were offered to newly hatched Argentinean cockroaches, black soldier flies, yellow mealworms, and house crickets. The first two species are potentially interesting as a feed ingredient, while the latter two are considered edible for humans. Feed conversion efficiency, survival, development time, as well as chemical composition (nitrogen, phosphorus, and fatty acids), were determined. The Argentinean cockroaches and the black soldier flies converted feed more efficiently than yellow mealworms, and house crickets. The first two were also more efficient than conventional production animals. On three of the four diets yellow mealworms and house crickets had a feed conversion efficiency similar to pigs. Furthermore, on the most suitable diet, they converted their feed as efficiently as poultry, when corrected for edible portion. All four species had a higher nitrogen-efficiency than conventional production animals, when corrected for edible portion. Offering carrots to yellow mealworms increased dry matter- and nitrogen-efficiency and decreased development time. Diet affected survival in all species but black soldier flies, and development time was strongly influenced in all four species. The chemical composition of Argentinean cockroaches was highly variable between diets, for black soldier flies it remained similar. The investigated species can be considered efficient production animals when suitable diets are provided. Hence, they could form a sustainable alternative to conventional production animals as a source of feed or food.     

Dietary choices by four captive slender lorises (Loris tardigradus) when presented with various insect life stages

The slender loris (Loris tardigradus) is a rare, nocturnal prosimian found only in the tropical rainforest of southern India and Sri Lanka. Little is known about their diet, though it is assumed that insects comprise a majority of their wild diet. Based on this assumption, captive lorises are offered a variety of insects or insect life stages; the species of insect or the life stage is often determined by what is easiest to buy or rear. Captive lorises at the Duke Lemur Center (DLC) were offered the opportunity to choose which life stage of mealworms (Tenebrio molito), superworms (Zophobus morio), or waxworms (Galleria mellonella) they preferred. The DLC captive lorises did not select the largest life stages of any insect offered. They preferred the larvae stage to the adult stage in all three insect species, and males and females had different insect species and life stage preferences. Zoo Biol 30:189–198, 2011. © 2010 Wiley‐Liss, Inc.     

Gut loading to enhance the nutrient content of insects as food for reptiles: A mathematical approach

A variety of commercially raised insects are fed to insectivorous reptiles, but information concerning appropriate diets used to feed these insects is limited. In the present study, house crickets (Acheta domesticus adults and nymphs), mealworms (Tenebrio molitor larvae), and silkworms (Bombyx mori larvae) were fed diets containing graded levels of calcium (Ca) and/or vitamin A–nutrients that are low or absent in most insects. Diets and insects were analyzed for moisture, Ca, phosphorus (P), and vitamin A. For adult crickets and cricket nymphs, body Ca and vitamin A concentrations increased in a linear fashion with increasing levels of dietary Ca or vitamin A. Ca concentrations of silkworms also increased in a linear fashion with increasing levels of dietary Ca. For mealworms, body Ca and vitamin A concentrations increased in a nonlinear fashion with increasing levels of dietary Ca or vitamin A. These regression equations, in conjunction with insect nutrient composition, allow for the calculation of the optimum nutrient concentration for gut‐loading diets. Final recommendations were based on National Research Council (NRC) requirements for rats, adjustments for the energy content of the insects, and nutrient overages as appropriate. Gut‐loading diets for crickets (adults and nymphs) should be supplemented to contain the following nutrients, respectively: Ca (51 and 32 g/kg), vitamin A (8,310 and 5,270 µg retinol/kg), vitamin D (300 and 190 µg cholecalciferol/kg), vitamin E (140 and 140 mg RRR‐α‐tocopherol/kg), thiamin (31 and 21 mg/kg), and pyridoxine (20 and 10 mg/kg). Gut‐loading diets for mealworms should be supplemented to contain the following nutrients: Ca (90 g/kg), iron (51 mg/kg), manganese (31 mg/kg), vitamin A (13,310 µg retinol/kg), vitamin D (460 µg cholecalciferol/kg), vitamin E (660 mg RRR‐α‐tocopherol/kg), thiamin (5 mg/kg), vitamin B₁₂ (650 µg/kg), and methionine (29 g/kg). Gut‐loading diets for silkworms should be supplemented to contain the following nutrients: Ca (23 g/kg), iodine (0.7 mg/kg), vitamin D (140 µg cholecalciferol/kg), vitamin E (70 mg RRR‐α‐tocopherol/kg), and vitamin B₁₂ (226 µg/kg). Zoo Biol 22:147–162, 2003. © 2003 Wiley‐Liss, Inc.     

Dietary enrichment of edible insects with omega 3 fatty acids

Edible insects are advocated as sustainable and healthy food and feed. However, commercially produced insects are often low in n‐3 fatty acids and have suboptimal n‐6/n‐3 ratios. A certain amount and proportion of these FAs is required to optimize human health. Flaxseed oil consists primarily (57%) out of alpha‐linolenic acid. An experiment was conducted to quantify the effect of flaxseed oil provision on fatty acid composition and to determine the quantity needed to attain a beneficial n‐6/n‐3 ratio. Three species were used in the experiment: house crickets (Acheta domesticus [L.]), lesser mealworms (Alphitobius diaperinus [Pfanzer]) and black soldier flies (Hermetia illucens [L.]). These were provided with either a control diet or a diet enriched with 1%, 2%, or 4% flaxseed oil during their larval/nymphal stage. Fatty acid profiles of diets and insects were determined via GC‐MS. The three species had distinct fatty acid profiles on all four diets, but responded similarly to flaxseed oil addition. For each percent added to the diet, the alpha‐linolenic acid content of the insects increased by 2.3%–2.7%. Four percent addition increased the n‐3 fatty acid content 10–20 fold in the three species and thereby strongly decreased n‐6/n‐3 ratios from 18–36 to 0.8–2.4. A ratio below 5 is considered optimal for human health and was achieved by 2% flaxseed oil inclusion for house crickets and lesser mealworms, and at 1% inclusion for black soldier flies. Adding a source of n‐3 fatty acids to insect diets can thus improve the nutritional quality of insects.     

Soil quality around a solid waste dumpsite in Port Harcourt, Nigeria

The levels of soil parameters and selected heavy metals around a solid waste dumpsite receiving untreated wastes from all sources and a control site within Port Harcourt, Nigeria have been examined. Top soil (0–15 cm) and sediment samples were collected and analysed for pH value, particle size, total nitrogen, potassium, available phosphorus, organic matter, effective cation exchange capacity, cadmium, nickel and lead using standard methods. The results showed that the waste dump contributed to the high levels of nutrients and heavy metals. The dry season mean concentrations were: organic matter (5.28 ± 1.34% or 132,422.4 kg ha^?1), K (1.60 ± 0.52 meq per 100 g), N (0.09 ± 0.06% or 2257.2 kg ha^?1), Av.P (15.11 ± 7.57 μg g^?1), Cd (1.34 ± 0.72 μg g^?1), Ni (4.10 ± 1.63 μg g^?1) and Pb (38.85 ± 22.18 μg g^?1) while the wet season mean concentrations were organic matter (5.46 ± 1.39% or 136,936.8 kg ha^?1), K (2.79 ± 0.81 meq per 100 g), N (0.10 ± 0.05% or 2508 kg ha^?1), Av.P (9.22 ± 2.69 μg g^?1), Cd (1.72 ± 1.22 μg g^?1), Ni (14.95 ± 14.94 μg g^?1) and Pb (53.50 ± 40.09 μg g^?1). There was efficient mineralization process in the area. The texture of soil on the main dumpsite was loamy sand, which suggests that the ground water in the area is susceptible to contamination by surface pollutants. The texture of soil at the control site is sandy loam while sediment has the textural class of sand. Decomposed organic materials and agricultural activities influenced the texture of soils. The soils from the main dump and sediment were slightly alkaline while the control soil was moderately acidic. In both seasons, a significant variation exists (P < 0.05) between the metal concentrations in soil at the main dump and those in the sediments with a positive correlation (r = 0.572149) in the wet season and (r = 0.956647) in the dry season. The presence of liming materials and activities of microorganisms on the waste dump increased the pH of the soils. The accumulation of nutrients results in the luxuriant growth of plants/crops on the waste dump.     

Do supplements of Acacia mearnsii and grapeseed extracts alone or in combination alleviate metabolic nitrogen load and manure nitrogen emissions of lambs fed a high crude protein diet?

ABSTRACT

Diets excessive in crude protein (CP) are unfavourable in terms of metabolic and environmental load. Dietary phenols, often binding to dietary proteins, may alleviate these problems. In an experiment with 60 lambs (3.2 ± 1.6 months of age; 29.7 ± 5.1 kg body weight), kept in pairs, five diets were tested. A diet with 157 g CP/kg dry matter (DM) served as negative control. Four diets with on average 229 (225–233) g CP/kg DM remained either non-supplemented or were supplemented with 13 g/kg DM of Acacia mearnsii extract, grapeseed extract, or a combination of both (26 g extract/kg DM). The analysed concentrations of total extractable phenols were 7.1, 8.1, 14.3, 16.6 and 25.4 g/kg DM for low (CP^?) and high CP (CP⁺), and high CP with acacia (CP^+A), grapeseed (CP^+G) and acacia plus grapeseed (CP^+AG), respectively. Diets were fed for 10 weeks, and for 6 d faeces and urine were collected and subsequently stored as complete manure for 8 weeks. In blood plasma, phenol concentrations and activities of enzymes indicating liver and kidney stress were analysed. The CP⁺ diet increased apparent digestibility of N and its removal with the urine, with the expected increase in gaseous N emissions from the manure (13.5 vs 6.5 g/lamb per day during 8 weeks) compared to CP^?. However, no clear signs of metabolic stress were detected. Supplementing the extracts did not impair intake, growth performance and digestibility. Only the supplementation with both extracts decreased urinary N proportion of manure N, and the concomitant weak decline in gaseous emission from the manure was not significant. At least part of the phenols of both extracts seem to be bioavailable as their supplementation elevated blood plasma phenol concentrations by 15% to 40% compared to CP⁺. A combination of both extracts did not result in a further increase. Further studies have to identify the minimally effective dosage for reducing N emissions, which, at the same time, does not cause adverse side effects in performance.     

Small ruminants: Digestive capacity differences among four species weighing less than 20 kg

Small ruminants are generally classified as either browsers or frugivores. We compared intake and digestion in one browsing species, the pudu (Pudu pudu), body weight 9 kg, and three frugivorous species, the red brocket (Mazama americana), 20 kg, the bay duiker (Cephalophus dorsalis), 12 kg, and Maxwell's duiker (C. maxwellii), 9 kg. Rations comprised: a commercial grain and alfalfa pellet, a small amount of vegetables, and mixed hay. Across species, neutral-detergent fiber (insoluble fiber) consumed averaged 34.2 ± 2.6% of dry matter (DM) while the crude protein consumed averaged 16.1 ± 0.5% DM. Apparent DM digestion was similar in pudu (75.2 ± 4.7%), brocket (73.2 ± 1.1%), and Maxwell's duikers (73.0 ± 2.8%), and significantly lower (P = 0.0167) in bay duikers (67.1 ± 4.3%). There were significant differences among species in digestibilities of neutral-detergent fiber, hemicellulose, and cellulose, but they did not follow body size differences, since larger species were expected to show higher digestion coefficients for fiber compared to smaller species. The type of fiber fed may have influenced these results. Frugivores may be adapted to a diet of soluble fibers, as might be found in wild fruits, instead of the insoluble fibers in the diet fed. Passage trials were conducted on the two smallest species. The mean transit time for pudu was 29.9 ± 0.8 hr, and for the Maxwell's duiker was 42.2 ± 6.4 hr. © 1996 Wiley-Liss, Inc.     

The effects of prey species on food conversion efficiency and growth of an insectivorous lizard

Little is known about the effects of different prey species on lizard growth. We conducted a 6‐week study to determine the relative effects of prey species on growth parameters of hatchling western fence lizards, Sceloporus occidentalis. Lizards were fed house cricket nymphs, Acheta domesticus, or mealworm larvae, Tenebrio molitor. The effects of prey species on growth were determined by measuring prey consumption, gross conversion efficiency of food [gain in mass (g)/food consumed (g)], gain in mass, and gain in snout–vent length. Lizards grew well on both the prey species. However, lizards that fed on crickets consumed a significantly higher percentage of their body mass per day than those fed mealworms. Nevertheless, lizards that consumed mealworms ingested significantly more metabolizable energy, had significantly higher food conversion efficiencies, significantly higher daily gains in mass, and significantly greater total growth in mass than lizards that fed on crickets. Zoo Biol 27:181–187, 2008. © 2008 Wiley‐Liss, Inc.     

The distribution of dimethylsulfoniopropionate in tropical Pacific coral reef invertebrates

Dimethylsulfoniopropionate (DMSP) is an important component of the global sulfur cycle and may be involved, via its cleavage product dimethylsulfide, in climate regulation. Although it is common in many algae, reports of DMSP in animals, particularly tropical invertebrates, are limited. This study examined the distribution of DMSP in a diverse group of coral reef invertebrates. DMSP was present in all 22 species of cnidarians and ranged from 9 to 723 μmol g⁻¹ of dry mass (DM) with a mean (± 1SD) of 110 ± 180 μmol g⁻¹ DM. It was not detected in a flatworm and an ascidian or in two of five sponges. Concentrations in sponges ranged from undetectable to 16 μmol g⁻¹ DM with a mean of 4 ± 7 μmol g⁻¹ DM. Within the cnidarians, DMSP concentrations did not differ among orders. Among cnidarian species, DMSP concentrations were correlated with symbiotic zooxanthellae densities. Within cnidarian species, DMSP concentrations of individuals were positively correlated with zooxanthellae densities in three of the four species examined. We speculate that DMSP is dietarily derived in sponges and derived from zooxanthellae in the cnidarians. The functions of DMSP in coral reef invertebrates are not known.     

Reduction of Plasma Leptin Concentrations by Arginine but Not Lipid Infusion in Humans

Objective: We examined short-term effects of arginine infusion on plasma leptin in diabetic and healthy subjects. Research Methods and Procedures: Arginine stimulation tests were performed in C-peptide negative type 1 [DM1; hemoglobin A_1c; 7.3 ± 0.3%], hyperinsulinemic type 2 diabetic (DM2; 7.6 ± 0.7%), and nondiabetic subjects (CON; 5.4 ± 0.1%). Results: Fasting plasma leptin correlated linearly with body mass index among all groups (r = 0.61, p = 0.001). During arginine infusion, peak plasma insulin was lower in DM1 than in DM2 (p < 0.05) and CON (p < 0.01). Plasma leptin decreased within 30 minutes by ∼11% in DM1 (p < 0.001), DM2 (p < 0.01), and CON (p < 0.005), slowly returning to baseline thereafter. Plasma free fatty acids (FFAs) were higher in DM1 (0.6 ± 0.1 mM) and DM2 (0.6 ± 0.1 mM) than in CON (0.4 ± 0.1 mM, p < 0.05) and transiently declined by ∼50% (p < 0.05) at 45 minutes in all groups before rebounding toward baseline. To examine the direct effects of FFAs on plasma leptin, we infused healthy subjects with lipid/heparin and glycerol during fasting, and somatostatin-insulin (∼35 pM) -glucagon (∼90 ng/mL) clamps were performed. In both protocols, plasma leptin continuously declined by ∼25% (p < 0.05) during 540 minutes without any difference between the high and low FFA conditions. Discussion: Arginine infusion transiently decreased plasma leptin concentrations both in insulin-deficient and hyperinsulinemic diabetic patients, indicating a direct inhibitory effect of the amino acid but not of insulin or FFAs.     

Contribution of terrestrial invertebrates to the annual resource budget for salmonids in forest and grassland reaches of a headwater stream

1. The annual input, contribution to the diet of salmonids, and quantitative input of terrestrial invertebrates to four reaches with contrasting forest (n=2) and grassland riparian vegetation (n=2) were compared in a Japanese headwater stream.
2. The annual input of terrestrial invertebrates falling into the forest reaches (mean±1 SE=8.7×10³±0.3×10³ mg m^?2 year^?1) was 1.7 times greater than that in the grassland reaches (5.1×10³±0.8×10³ mg m^?2 year^?1), with clear seasonality in the daily input of invertebrates in both vegetation types. The daily input, however, differed between the vegetation types only in summer, when it rose to a maximum in both vegetation types.
3. Fish biomass also differed among the seasons in both vegetation types, being less in the grassland reaches. The contribution of terrestrial invertebrates to the salmonid diet in the forest and grassland reaches was 11 and 7% in spring, 68 and 77% in summer, 48 and 33% in autumn, and 1 and 1% in winter, respectively. The prey consumption rate of fish, which was similar between the vegetation types, increased with stream temperature and was highest in summer. Terrestrial invertebrates supported 49% (mean±1 SE=5.3×10³±0.4×10³ mg m^?2 year^?1) of the annual, total prey consumption (10.9×10³±1.7×10³ mg m^?2 year^?1) by salmonids in the forest and 53% (2.0×10³±0.3×10³ mg m^?2 year^?1) (3.8×10³±0.6×10³ mg m^?2 year^?1) in the grassland reaches.
4. Salmonids were estimated to consume 51 and 35% of the annual total (falling plus drift) input of terrestrial invertebrates in the forest and grassland reaches, respectively. The input of terrestrial invertebrates by drift, however, was almost equal to the output in both vegetation types, suggesting that the reach‐based, in‐stream retention of terrestrial invertebrates almost balanced these falling in.
5. Difference in the riparian vegetation, which caused spatial heterogeneity in the input of terrestrial invertebrates, could play an important role in determining the local distribution of salmonids.     

Microbial and decomposition efficiencies of monoculture and polyculture vermireactors,based on epigeic and anecic earthworms

Efforts have been made to evaluate the microbial and decomposition efficiency of three different vermireactors: (i) polyculture (introducing equal numbers of anecic and epigeic earthworms), (ii) monoculture (anecic) and (iii) monoculture (epigeic), designed by using earthworms of two different ecological categories i.e. anecic (Lampito mauritii Kinberg) and epigeic (Eisenia fetida (Savigny)). The microbial load of vermireactors was measured through substrate-induced respiration rate (SIR), microbial biomass N content and rate of dehydrogenase activity, while mineralization rate was evaluated measuring some chemical parameters of the substrate. Earthworms caused a decrease (as compared to initial value) in pH (41.9–80.7%), organic C (10.3–14.2%) and C:N ratio (41.9–80.7%) and an increase in total N (29.1–58.8%), NH₄-N (876.1–1485.7%), NO₃-N (29081.8–56792.6%), available P (16–19.4%) and exchangeable K (9.8–13.5%) contents of the substrate. The mineralization efficiency of the reactors was in the order: polyculture (epigeic + anecic) > monoculture (anecic) > monoculture (epigeic). The polyculture reactor showed the maximum rate of SIR (2.91 ± 0.2 mg CO₂ g⁻¹ substrate), microbial biomass N (3108.1 ± 289.2 mg N g⁻¹ substrate), and dehydrogenase activity (2453.3 ± 379.8 μg g⁻¹ substrate 24 h), while in the monoculture (epigeic) the lowest values of the same parameters were observed. It is concluded that the observed differences among reactors were due to different feeding behaviour and niche structures of epigeic and anecic earthworms. Data suggests that burrowing earthworms in waste-decomposing-system not only enhance the microbial efficiencies, but at the same time also accelerate the organic matter mineralization in a vermireactor. However, most of the previous studies were based on monoculture reactors (using epigeic earthworms) which have been recommended for waste decomposition operations, but this study revealed that polyculture vermicomposting (adding of burrowing worms with epigeic earthworms in vermicomposting system) might be beneficial for rapid decomposition of organic wastes.     

Optimization of extracellular lipase production from the biocontrol fungus Nomuraea rileyi

Lipases are important cuticle-degrading enzymes that hydrolyze the ester bonds of waxes, fats and lipoproteins during the infection of insects by the fungus Nomuraea rileyi. Lipase production by the N. rileyi strain MJ was optimized by varying environmental and nutritional conditions in culture medium containing different vegetable oils at various concentrations with shaking at 150 rpm for 8 days at 25°C. The maximum lipase production was obtained using castor oil (30.5±0.6 U mL^?1), followed in order by coconut oil (20.8±0.4 U mL^?1), olive oil (20.8±0.4 U mL^?1) and cottonseed oil (20.6±0.4 U mL^?1). The highest lipase activity (37.7±0.4 U mL^?1) was obtained when castor oil was used at a concentration of 4% (v/v) of basal medium. When the surfactant Tween 80 was added at the fourth day rather than at the beginning of incubation, a maximum lipase activity of 44.9±3.5 U mL^?1 was obtained. The optimal temperature and pH for lipase production were 25°C and pH 8.0, respectively. This is the first report on lipase production by the biocontrol fungus N. rileyi.     

Do endogeic earthworms change plant competition? A microcosm study

Plants compete for limited resources. Although nutrient availability for plants is affected by resource distribution and soil organisms, surprisingly few studies investigate their combined effects on plant growth and competition. Effects of endogeic earthworms (Aporrectodea jassyensis), root-knot nematodes (Meloidogyne incognita) and the spatial distribution of ¹⁵N labelled grass litter on the competition between a grass (Lolium perenne), a forb (Plantago lanceolata) and a legume (Trifolium repens) were investigated in the greenhouse. Earthworms promoted N uptake and growth of L. perenne. Contrastingly, shoot biomass and N uptake of T. repens decreased in the presence of earthworms. P. lanceolata was not affected by the earthworms. We suggest that earthworms enhanced the competitive ability of L. perenne against T. repens. Nematodes increased the proportion of litter N in each of the plant species. Litter distribution (homogeneous vs. patch) did not affect the biomass of any plant species. However, P. lanceolata took up more ¹⁵N, when the litter was homogeneously mixed into the soil. The results suggest that endogeic earthworms may affect plant competition by promoting individual plant species. More studies including decomposers are necessary to understand their role in determining plant community structure.