Synbiotic effect of Bacillus mycoides and organic selenium on immunity and growth of marron,Cherax cainii (Austin, 2002)

The present feeding trial examined the effect of synbiotic use of Bacillus mycoides and organic selenium (OS) as Sel‐Plex on marron immunity, growth and survival. The marron were cultured in recirculated tanks and fed test diets consisting of a basal diet; basal diet supplemented with B. mycoides (10⁸ CFU g^?1 of feed); basal diet supplemented with OS (Sel‐Plex) (0.2 g kg ^{? 1} of feed) and basal diet supplemented with synbiotic (B. mycoides at 10⁸ CFU g^?1 and OS 0.2 g kg ^{? 1} feed) diet, in triplicate. The effect of the prebiotic OS (Sel‐Plex) on the growth rate of B. mycoides was also studied in vitro. The results suggested that synbiotic use of B. mycoides and OS significantly improved some immune parameters of marron, particularly the glutathione peroxidase, and to some extent total haemocyte counts. However, the synbiotic feed did not synergistically improve marron growth, in fact the use of B. mycoides‐supplemented diet alone demonstrated significantly higher growth in marron compared with the growth of marron fed on other test diets. Supplementation of the basal diet with host origin B. mycoides significantly increased the intestinal bacterial population (3.399 ± 825 CFU g ^{? 1} of gut) in marron compared with other diets. Organic selenium as Sel‐Plex in Trypticase Soya Broth also confirmed that OS did not increase the amount of growth of B. mycoides and resulted in a lower intestinal bacterial population in the synbiotic diet‐fed marron. In conclusion, synbiotic of OS and B. mycoides may improve a particular immune parameters of marron and to a lesser extent their growth.     

Effect of body weight on the chemical composition and collagen content of snakehead fish <Emphasis Type="Italic">Channa striata</Emphasis> skin

Snakehead fish (Channa striata) skin is a fishery by-product that has the potential for further processing because it contains a high amount of organic matter. This study investigates the effect of body weight on the chemical composition and collagen content of snakehead fish skin. This study used fresh snakehead fish of either gender. Their body weights were divided into three groups: small, medium, and large size. The characteristics of snakehead fish skin included proximate composition, amino acid content, collagen content, microstructure, and minerals. Snakehead fish skin from fish of different body weights indicated that the moisture content and ash tended to decrease, the protein content was relatively stable, and the lipid content tended to increase with increasing body weight. Glycine and proline comprised the highest percentages of amino acids at all levels of body weight, and the presence of hydroxyproline showed that snakehead fish skin was the source of collagen. There was no significant difference in body weight observed on collagen protein content of the skin. This study on the microstructure and mineral content of snakehead fish skin can be used as supporting information to promote the potential utility and economic value of the skin.     

Presence of less-preferred hosts of the aphid parasitoids <Emphasis Type="Italic">Aphidius ervi</Emphasis> and <Emphasis Type="Italic">Praon volucre</Emphasis> reduces parasitism efficiency

Parasitoids are characterized by a defined range of hosts, either more specialist or generalist. Under natural conditions, females may encounter different host species on the same plant or in the same location. In this case, their preference for one host could influence their choice. However, the presence of less suitable hosts may also affect their choice and, in some cases, may reduce their interest in a patch where both preferred and less preferred hosts are available. The aim of the present study was to test the consequences of the simultaneous presence of three cereal aphids (Sitobion avenae Fabricius, Metopolophium dirhodum Walker, and Rhopalosiphum padi Linnaeus) on the parasitism by two of their parasitoids, Aphidius ervi Haliday and Praon volucre Haliday. Firstly, in the no-choice experiment, A. ervi parasitized on S. avenae at a significantly higher rate as compared to M. dirhodum, whereas no parasitism on R. padi was observed. P. volucre parasitized the three species of cereal aphids with a significant preference for S. avenae. Interestingly, when two or three host species were offered simultaneously in the same quantity to pairs of parasitoids, the level of parasitism was less than that observed for one host species alone. This observation exhibits a distractive effect on non-host species, from the defense mechanism of a non-suitable host or from the perception of bad quality patches. These results raise the question of the practical application of inundative release of parasitoids for biocontrol when several hosts are available simultaneously.     

Salinity stress response in estuarine fishes from the Murray Estuary and Coorong,South Australia

Estuaries are unstable ecosystems and can be changed by the environmental and anthropogenic impact. The Murray Estuary and Coorong were degraded by drought and low freshwater input in the last decade and therefore transformed into the largest hyper-saline lagoon in Australia. This study evaluates the physiological stress of two estuarine fish species (small-mouthed hardyhead Atherinosoma microstoma and Tamar goby Afurcagobius tamarensis) to the induced salinity change in captivity. The test fishes were collected from the Coorong and transported to the laboratory in the water from the Coorong. Each fish species was exposed to different levels of salinity, and a number of enzymes were assessed to measure the stress response of fish to salinity change. The activity of reactive oxygen species was significantly increased with the salinity change in both fish species compared with the fish in the control. Significant salinity effect on superoxide dismutase activity was observed on Tamar goby but not on small-mouthed hardyhead. Conversely, the impact of salinity on catalase activity was detected on small-mouthed hardyhead but not on Tamar goby. The study reveals that the induction of physical stress by salinity changes occurred in both Tamar goby and small-mouthed hardyhead despite the varying response of antioxidant enzymes between fish species. The study provides an insight into the understanding of physiological adaptation in estuarine fish to salinity change. The results could improve our knowledge on stress response and resilience of estuarine fish to hypo- and hyper-salinity stress.     

A comparison of the effect of organic acids and dicalcium phosphate supplementation on phosphorus bioavailability,growth performance and digestive enzyme activities of Labeo rohita fingerlings

The effect of organic acids (OA) and dicalcium phosphate (P_i) supplementation in the feed of Labeo rohita fingerlings was studied by formulating seven practical diets, designed as D1 with no feed additives {dicalcium phosphorus (P_i) and organic acid (OA) blend} while, D2, D3, D4 and D5 were supplemented with P_i at the graded levels of 5, 10, 15 and 20 g/kg, respectively, whereas D6 and D7 contained blend of OA at 15 and 30 g/kg, respectively. The diet supplemented with OA blend exhibited increase (p < .05) in growth of L. rohita fingerlings compared with the diet supplemented with P_i. The OA supplementation at both levels showed significant improvement in nutrients digestibility and minerals absorption in fingerlings. Moreover, in case of muscle proximate composition, crude fat (CF) and crude protein (CP) were increased (p < .05) with the inclusion of OA blend in the diet while crude ash (CA) was improved by P_i supplementation. Additionally, digestive enzyme activities were not affected (p ? .05) by OA blend supplementation while increased activities were observed in the fingerlings fed with P_i diet. Consequently, supplementation of OA blend in the diet improved the growth performance and nutrient status while P_i enhanced digestive enzyme activities of L. rohita fingerlings.     

Insecticide resistance inFrankliniella occidentalis: Corroboration of laboratory assays with field data and cross-resistance in a cypermethrin-resistant strain

Field efficacy of five insecticides to a greenhouse strain ofFrankliniella occidentalis (Pergande) (Thysanoptera: Thripidae) of known resistance status was studied. In a greenhouse trial, the mortality of aF. occidentalis strain (Uncali) which exhibited resistance only against cypermethrin in laboratory assays, reached 56%, 68%, 82%, 94% and 99%, 24 h after application of abamectin, cypermethrin, endosulfan, malathion and methomyl, respectively. In the laboratory, for larval mortality equal to that achieved in the field, much lower doses — half of the field dose of cypermethrin and endosulfan, and one-third and one-sixth of malathion and methomyl, respectively, were required in topical application. Because of differences between laboratory and field responses ofF. occidentalis to insecticides, a sound resistance evaluation program to determine field efficacy of insecticides is needed. Resistance increased 28.0- and 139.3-fold at LC₅₀ in theF. occidentalis strain subjected to 27 and 44 cycles of cypermethrin selection, respectively. A slight cross-resistance of two- to threefold was found with endosulfan, malathion and methomyl and no cross-resistance was observed with abamectin. http://www.phytoparasitica.org posting August 4, 2008.     

Exogenous Calcium Supplementation Improves Salinity Tolerance in BRRI Dhan28; a Salt-Susceptible High-Yielding Oryza Sativa Cultivar

Journal of Crop Science and Biotechnology - Salinity is one of the most brutal abiotic stressors, commencing a great stumbling block in the way of attaining food security in Bangladesh. Cultivation...     

Remobilization and utilization of phosphorus in wheat cultivars under induced phosphorus deficiency

A solution culture study was conducted to compare the phosphorus (P) remobilization efficiency of four wheat cultivars under induced P deficiency. Wheat cultivars, i.e. Sarsabz, NIA-Sunder, NIA-Amber and NIA-Saarang were initially grown on adequate P nutrition for 30 days and then exposed to P-free nutrient solution for next 15 days to study P remobilization. Completely randomized design (CRD) with ten replicates per cultivar was employed. Cultivars varied for biomass production, P concentration, P uptake, and P utilization efficiency at both harvests. Overall, more than 75% of absorbed P was mobilized from older leaves to younger leaves as well as roots of all cultivars during P-omission period. However, cultivars could not produce significant variations (P < 0.05) in P remobilization, which implied that P remobilization was only a stress response to P deficiency in wheat cultivars and it could not be related to P utilization efficiency of these cultivars.     

Evaluation of foot and mouth vaccination for yak (<Emphasis Type="Italic">Bos grunniens</Emphasis>) in Pakistan

In northern Pakistan, many farming communities rely on domestic yak (Bos grunniens) as a principle source of income. A 2006 participatory disease surveillance report from this region indicated that foot-and-mouth disease (FMD) is the most prevalent annual disease of yak. Our objectives of this study were to determine exposure levels of yak to FMD virus; implement a vaccination program based on current, regional FMD virus serotypes and subtypes; and quantify immune responses following vaccination. Blood samples were used to determine pre-vaccination exposure of animals to FMD virus by antibody presence to non-structural proteins of FMD virus using a 3-ABC trapping indirect ELISA. Vaccine used consisted of FMD serotypes ‘O’ (PanAsia-2), ‘A’ (Iran-05), and ‘Asia-1’ (Shamir), but changed later during the study to match newly circulating viruses in the country (‘O’-PanAsia-2; ‘A’-Turk-06 and Asia-1-Sindh-08). Three hundred sixty-three blood samples were tested from selected villages to determine pre-vaccination FMD virus exposure in yak with an average of 37.7%. Immune responses from initial vaccination and booster dose 30 days later showed clear protective levels (as mean percent inhibition) of antibodies against structural proteins of serotypes ‘O,’ ‘A,’ and ‘Asia-1.’ These responses remained above threshold positive level even at day 210 following initial vaccination. Results of sero-surveillance and anecdotal information of repeated FMD outbreaks demonstrate the persistence of FMD virus of yak in northern Pakistan. Laboratory results and field observations clearly indicated that yak can be protected against FMD with a good quality vaccine with FMD serotype(s) matching current, regionally circulating FMD virus.