The effects of host plant species on adult oviposition and larval performance of the aphid predator Aphidoletes aphidimyza

1. Although preference–performance relationships in insects are typically studied in a bi-trophic context, it is well known that host plants can affect both the preference and performance of natural enemies of herbivorous insects. 2. This study presents evidence from field and laboratory studies that two species of milkweeds, the putatively less defended Asclepias incarnata and the putatively more defended Asclepias syriaca, differentially affect adult oviposition and larval performance in Aphidoletes aphidimyza, an aphid-feeding predatory midge, independent of aphid density. 3. Host plant species affected predatory fly larvae abundance by a factor of 50 in the field and a factor of 8 in the laboratory. Larval and adult emergence rates in our laboratory studies provided strong evidence for reduced performance on A. syriaca. Oviposition in choice and no-choice settings provided some evidence for preference for A. incarnata, and a potentially suppressive effect of A. syriaca. 4. The results provide limited support for the hypothesis that natural selection can lead to positive correlations between adult oviposition preferences and larval performance upon various food sources, even when predatory insects oviposit onto host plants of their herbivorous prey. 5. Preference and performance are not perfectly aligned in this system, however, because ovipositing females do not reject A. syriaca entirely. Potential explanations for mismatches between preference and performance in this system include the neural constraints associated with being a generalist, adaptive time-limited foraging strategies, and unique evolutionary histories of laboratory colonies compared with wild insects.     

Temperature,deltamethrin-resistance status and performance measures of Plutella xylostella: complex responses of insects to environmental variables

1. Worldwide, the excessive use of insecticides has resulted in field-evolved insecticide-resistant populations of diamondback moth (DBM), Plutella xylostella. A deltamethrin-resistant DBM population from the field was divided into two subpopulations in the laboratory. One population (S-strain) was maintained with no further exposure to insecticides, whereas the other population (R-strain) was maintained under a regime of intermittent selection with deltamethrin. 2. Individuals from both strains were reared at constant temperatures in the range 10–35 °C in the absence of deltamethrin, and the effects of rearing temperature on various traits were investigated. At the time of experimentation, the R-strain was 20-fold more resistant to deltamethrin than the S-strain. 3. Temperature differentially affected developmental time, adult life span, pupal weight, and fecundity of both strains. Although both strains laid eggs after being reared at 10 °C, few of these eggs were fertile. The R-strain developed significantly faster than the S-strain. The integrated performance of the S-strain and R-strain was greatest at 25 and 15 °C, respectively. 4. The present study provides important information on the complexities of the outcomes of the interactions between ectotherms and temperature. Specifically, temperature-trait relationships may not be unimodal, and ectotherm genotypes (in this case insecticide-resistance status) and abiotic stresses can interact with unpredictable outcomes. 5. Current models predicting DBM population dynamics and relative abundance in different locations do not consider different thermal biologies of different genotypes. The present study shows the dramatic effects of environment on many parameters used in these models and will help to enhance their accuracy, and thus their utility.     

Evaluation of environmentally conscious manufacturing programs using a three-hybrid multi-criteria decision analysis method

Environmental management, being an important component in strategies for achieving sustainable development of processes and products, has emerged as a proactive approach in majority of the manufacturing organizations. From the strategic perspective environmentally conscious manufacturing (ECM) programs lead to better environmental management practice. The objective of the current paper is to present an integrated and holistic framework to evaluate ECM programs. This framework combines three multi-criteria decision analysis (MCDA) methods to consider eight major environmentally conscious manufacturing indicators (ECMI) in order to identify the efficiency of each ECM program. First the interdependence relationship among the ECMIs is established using decision-making trail and evaluation laboratory (DEMATEL). Then a range of weightage (i.e. upper and lower bounds) is created for each ECMI using analytic network process (ANP) to include managerial preferences. Finally, this range of weightage for each indicator is applied to perform restricted multiplier data envelopment analysis (RMDEA). Results show that the technical efficiency of the inefficient ECM programs for integrated RMDEA, on average, is calculated as 53.2% whereas traditional input oriented DEA provides the same score as 72.3%. This clearly indicates that integrated RMDEA is better than the input oriented DEA because same level of output could be produced with lesser resources if the ECM programs perform on the frontier. Hence, the advantage of this methodology is that the managerial preferences are successfully implemented through this newly developed hybrid methodology that will help to reduce less resource consumption and lead to better environmental policy.     

Influence of different prebiotics and mode of their administration on broiler chicken performance

In the post-antibiotics era, prebiotics are proposed as alternatives to antibiotic growth promoters in poultry production. The goal of this study was to compare in ovo method of prebiotic delivery with in-water supplementation and with both methods combined (in ovo+in-water) in broiler chickens. Two trials were conducted. Trial 1 was carried out to optimize the doses of two prebiotics, DN (DiNovo®, extract of beta-glucans) and BI (Bi²tos, trans-galactooligosaccharides), for in ovo delivery. The estimated parameters were hatchability and bacteriological status of the newly hatched chicks. Prebiotics were dissolved in 0.2 ml of physiological saline, at the doses: 0.18, 0.88, 3.5 and 7.0 mg/embryo; control group (C) was injected in ovo with 0.2 ml of physiological saline. Trial 2 was conducted to evaluate effects of different prebiotics (DN, BI and raffinose family oligosaccharides (RFO)) delivered in ovo, in-water and in a combined way (in ovo+in-water) on broiler chickens performance. The results of the Trial 1 indicated that the optimal dose of DN and BI prebiotics delivered in ovo, that did not reduce chicks’ hatchability, was 0.88 mg/embryo (DN) and 3.5 mg/embryo (BI). Both prebiotics numerically increased number of lactobacilli and bifidobacteria in chicken feces (P>0.05). In Trial 2, all prebiotics (DN, BI and RFO) significantly increased BW gain compared with the C group (P<0.05), especially during the first 21 days of life. However, feed intake and feed conversion ratio were increased upon prebiotics delivery irrespective of method used. Injection of prebiotics in ovo combined with in-water supplementation did not express synergistic effects on broilers performance compared with in ovo injection only. Taken together, those results confirm that single in ovo prebiotics injection into the chicken embryo can successfully replace prolonged in-water supplementation post hatching.     

Fluid replacement following dehydration reduces oxidative stress during recovery

To investigate the effects of hydration status on oxidative DNA damage and exercise performance, 10 subjects ran on a treadmill until exhaustion at 80% VO_2max during four different trials [control (C), 3% dehydration (D), 3% dehydration + water (W) or 3% dehydration + sports drink (S)]. Dehydration significantly decreased exercise time to exhaustion (D < C and S). Plasma MDA levels were significantly higher at pre-exercise in D than C. Plasma TAS was significantly lower at pre-exercise in C and S than in D, and was significantly lower in S than D at 60 min of recovery. Dehydration significantly increased oxidative DNA damage during exercise, but fluid replacement with water or sports drink alleviated it equally. These results suggest that (1) dehydration impairs exercise performance and increases DNA damage during exercise to exhaustion; and (2) fluid replacement prolongs exercise endurance and attenuates DNA damage.     

Degradation of cholecystokinin octapeptide,related fragments and analogs by human and rat plasma in vitro

The rate of degradation of cholecystokinin octapeptide, related fragments and analogs by human and rat plasma was investigated, using high pressure liquid chromatography for the separation and identification of the degradation products.CCK tetrapeptide showed a half-life of 13 min in human plasma while its cleavage in rat plasma occurred at a very high rate (half-life of less than 1 min).The kinetics of disappearance of both sulphated and unsulphated CCK-8 indicated more than a single rate of degradation; the faster degrading system showed a half-life of 18 min for unsulphated CCK-8 and of 50 min for the sulphated peptide in human plasma as compared respectively with 5 and 17 min in rat plasma. The cleavage of CCK-8 was inhibited by bestatin and puromycin, suggesting that aminopeptidases play a major role in the breakdown of this peptide.CCK-9 analogs were rapidly converted into their corresponding octapeptides (half-life of 2.7 min in human plasma). This conversion was inhibited by puromycin and bestatin, suggesting the participation of aminopeptidase(s) probably specific for basic amino acids.CCK decapeptide exhibited a greater stability than the nonapeptides (half-life of 30 and 45 min in human and rat plasma respectively) and also gave rise to CCK-8 as degradation product. This cleavage was not affected by aminopeptidase inhibitors but was decreased by aprotinin (Trasylol®), suggesting that trypsin-like and/or kallikrein-like enzyme(s) were involved in the plasma metabolism of this peptide.     

Regulation of carnitine status in ruminants and efficacy of carnitine supplementation on performance and health aspects of ruminant livestock: a review

Carnitine has long been known to play a critical role for energy metabolism. Due to this, a large number of studies have been carried out to investigate the potential of supplemental carnitine in improving performance of livestock animals including ruminants, with however largely inconsistent results. An important issue that has to be considered when using carnitine as a feed additive is that the efficacy of supplemental carnitine is probably dependent on the animal’s carnitine status, which is affected by endogenous carnitine synthesis, carnitine uptake from the gastrointestinal tract and carnitine excretion. The present review aims to summarise the current knowledge of the regulation of carnitine status and carnitine homeostasis in ruminants, and comprehensively evaluate the efficacy of carnitine supplementation on performance and/or health in ruminant livestock by comparing the outcomes of studies with carnitine supplementation in dairy cattle, growing and finishing cattle and sheep. While most of the studies show that supplemental carnitine, even in ruminally unprotected form, is bioavailable in ruminants, its effect on either milk or growth performance is largely disappointing. However, supplemental carnitine appears to be a useful strategy to offer protection against ammonia toxicity caused by consumption of high levels of non-protein N or forages with high levels of soluble N both, in cattle and sheep.     

Comparative effect of different dietary inulin sources and probiotics on growth performance and blood characteristics in growing–finishing pigs

The study was focused on assessment of the effect of an extract of long-chain inulin (LCI) and dried tubers of Jerusalem artichoke (JA) and a multispecies probiotic preparation as well as a combination thereof on growth performance and blood parameters of fattening pigs. In total, 144 pigs (initial body weight 30.0 ± 0.5 kg) were used in a 98-d experiment. The six dietary treatments consisted of the control diet (Con), diet Con supplemented with probiotics (ConP) and four diets supplemented with LCI or JA alone or with probiotics (diets LCIP and JAP). Throughout the fattening period, there was a beneficial effect of the probiotic supplementation to the inulin-containing diets and the average daily gain (ADG) was increased by supplementation of probiotics in combination with inulin sources (p < 0.05). At the end of the fattening period, ADG and feed conversion ratio (FCR) were higher after supplementation of LCI only (p < 0.05). Compared with group ConP, in groups LCI and JA, the ADG and FCR were improved (p < 0.05). Only in the first fattening stage, the addition of the prebiotics and/or probiotics had an impact on the level of white blood cells and some biochemical indices in pigs. In younger animals, probiotic or LCI supplementation increased the IgG level (p < 0.05). There was also an interaction between the probiotics and JA resulting in increased IgG and IgA concentrations (p < 0.05). In the finishing period, LCI addition increased the IgM level (p < 0.05), whereas JA addition increased IgG and IgM levels as well (p < 0.05). In conclusion, both dietary sources of inulin and probiotic supplementation can improve the fattening performance and health status of growing pigs.     

Performance,gut morphology and carcass characteristics of fattening rabbits as affected by particle size of pelleted diets

A review of past literature revealed inconsistencies in recommended feed particle size for optimal growth and productive performance of rabbits. Changing diet formulation and subsequent processing conditions may improve pellet texture and potentially affect rabbit performance. In the current study, two isoenergetic and isonitrogenous pelleted diets were formulated, which varied in the particle size of the concentrates (2 and 8 mm, respectively). The objective was to evaluate the effect of different particle sizes of compound diets on performance, nutrient utilisation, gut morphology, and carcass characteristics of fattening Italian White breed rabbits. The finely ground diet led to a significant improvement in feed efficiency and apparent digestibility of crude protein, ether extract, crude fibre and NDF, without any negative effect on gut morphology. Furthermore, a smaller particle size of concentrates in pelleted diets improved carcass traits. Meat colour parameters showed significant differences in longissimus lumborum and biceps femoris due to dietary treatments, but in both muscles pH values 1 h and 24 h after slaughter remained unchanged. It is concluded that a finely ground pelleted diet can be used to improve growth performance of rabbits without affecting carcass parameters.