Isolation and molecular characterization of entomopathogenic nematode,Heterorhabditis sp. from an arable land in Nigeria

The occurrence of entomopathogenic nematodes(EPNs) in arable soil samples from Nigeria was investigated using Baermann extraction tray and insect-bait(White's trap) techniques. Isolates were tested for infectivity using the larvae of Galleria mellonella(greater moth) and Tenebrio molitor(mealworm). The study revealed a new species of Heterorhabditis(MT371593) in soil samples that were randomly collected from an arable farmland cultivated with cassava TMS-30572 at the Teaching and Research Farm of Landmark University, Nigeria. Amplification of the internal transcribed spacer region(ITS) of the ribosomal DNA produced a nucleotide sequence of 933 base pairs(bp). A BLASTN search of Gen Bank showed that the sequence of the Nigerian isolate is identical at 99% similarity to that of Heterorhabditis sp. from Thailand. Infectivity test of the isolate showed 100% mortality against T. molitor larvae within 48 h of exposure while only 80% mortality was recorded for G. mellonella after 1 week of exposure. This is the first account of Heterorhabditis sp. in Nigeria. The varying degrees of infectivity against mealworm and greater moth observed in this study proved that the Nigerian isolate of Heterorhabditis sp. could potentially be an attractive option in the management of insect pests of cash crops.     

Rural livelihood benefits from participation in the taungya agroforestry system in Ondo State of Nigeria

This study examines the strategies and benefits of the taungya farming system to both the government and the rural economy in Nigeria. An interview survey was conducted in which data were collected from 115 randomly selected farmers in five villages in the Oluwa forest reserve, Ondo State, Nigeria. The study examines the extent of participation of rural dwellers in plantation development through taungya farming and the degree of success of this system as an afforestation method. The farmers were predominantly illiterate, within the age bracket of 35–54 years and with small farm holdings. Twenty nine percent relied totally on food from the forest reserve for their livelihood, while 71% also had farm holdings in free areas. Land within the reserve is allocated to farmers free of charge but compensation is paid to landlords on land from free areas. A statistically significant difference was detected in income from the two sources of farmland for the households and but not in the size of land allocated under taungya and free areas. About 184 farmers are involved in taungya annually, and 410 ha of Tectonia grandis has been established for the government of Ondo State.     

Apparent and standardised ileal amino acid digestibility of wheat distillers dried grains with solubles with or without exogenous protease in broilers and turkeys

1. The apparent (AIAAD) and standardised ileal amino acid digestibility (SIAAD) of wheat distillers dried grains with solubles (wheat-DDGS) was determined for broilers and turkeys at 28 d using two experiments.

2. A total of 84 male Ross 308 broiler chicks (Experiment 1) or 84 male BUT 10 turkey poults (Experiment 2) were offered a nutrient-adequate diet from d 1 to 23. On d 23, birds in each experiment were allocated to 4 treatments consisting of a nitrogen-free diet (NFD) (with or without protease) and an assay diet containing wheat-DDGS as the only source of amino acids (with or without protease) in a randomised complete block design.

3. In Experiments 1 and 2, the coefficient of AIAAD or SIAAD of Lys and Asp were low irrespective of protease. In Experiment 1, the coefficient of AIAAD ranged from 0.35 (Ala) to 0.75 (Pro) without protease, whereas the range was 0.42 (Thr) to 0.82 (Pro) with protease. Protease improved the coefficient of AIAAD for Arg and Pro and tended to improve the coefficient of AIAAD for Met. Without protease, the coefficient of SIAAD ranged from 0.51 (Ala) to 0.84 (Pro), whereas the range was from 0.65 (Ala) to 0.93 (Pro) with protease. Protease improved the coefficient of SIAAD of Arg, Leu, Phe, Met, Val and Pro.

4. In Experiment 2, the coefficient of AIAAD was lower than 0.50 for all amino acids except for Glu (0.70) and Pro (0.81) without protease. On the other hand, the coefficient of SIAAD ranged from 0.41 (Thr) to 0.89 (Pro) without protease, whereas the range was from 0.56 (Arg) to 0.88 (Pro) with protease supplementation. With the exception of Cys and Pro, protease improved the coefficient of AIAAD and SIAAD of all other amino acids by 0.05–0.19.

5. It was concluded that the AIAAD and SIAAD of wheat-DDGS are variable and are generally greater in broilers compared to turkeys at 28 d of age. Protease improved the ileal digestibility of a large number of amino acids in wheat-DDGS for broilers and turkeys.

     

Mechanisms and management of acaricide resistance for Tetranychus urticae in agroecosystems

Journal of Pest Science - The two-spotted spider mite, Tetranychus urticae Koch, is a constant threat to sustainable production of numerous economically important crops globally. Management of T....     

Induced Breeding of Two Clariid Catfishes Clurius gariepinus and Heterobranchus bidorsalis Using Tilapia Pituitary Extracts

Induced breeding trials of two clariid catfishes, Clarias gariepinus and Heterobranchus bidorsalis , were conducted using five doses (2, 4, 6, 8 or 10 mg/kg) of acetone-dried tilapia pituitary (ADTP) extracts. Oocyte maturation and ovulation were induced in female catfishes by single intramuscular injection of 6–10 mgkg ADTP; optimum results were obtained with 8 mgkg in both catfishes. At ambient temperature (27 ± 1 C). ovulation occurred within 14–18 h post-injection resulting in 16–20% increase in egg diameter. Fertilization and hatching percentages increased ( P < 0.05) with increases in hormone dosage. Survival of fry fed a mixed zooplankton diet was high (ranging from 79% to 85%) after 30 d of rearing.     

Multivariate characterisation of the phenotypic traits of Djallonke and Sahel sheep in Northern Ghana

The characterisation of the small ruminant populations in developing countries will play a major role in the maintenance of the genetic resources as the basis for future improvement in livestock production. The present study aimed at morphological characterisation of the two main breeds of sheep in Ghana by assessing variation within and between breed populations using principal component and discriminant analyses. The two breeds were the Sahel and the Djallonke sheep of both sexes and of two groups namely, young (1 year old, consisting of 74 animals) and mature sheep (≥2 years old, comprising 219 animals). The analysis of variance revealed significant (P?<?0.05) differences in the morphological traits of the Sahel and the Djallonke sheep breeds with higher values recorded for the former. Sexual dimorphism was in favour of male animals in all the morphological traits examined. Mature animals also had comparative advantage over the young. Two principal components were extracted to discern the structure of the two genetic groups. The most discriminating traits between the two sheep breeds were rump height, height at withers, neck girth and pin-bone width. Mahalanobis distance between the two genetic groups was 5.723 (P?<?0.0001). The developed discriminant functions clearly discriminated and classified the Sahel and the Djallonke sheep into their breeds of origin, thus yielding 100, 93.4 and 90.4 % accurate classification for the rams, ewes and the overall sheep population, respectively. The present approach would greatly help in establishing management and conservation policies for the sustainable production of the two Ghanaian sheep breeds.     

Logging Impacts in Tropical Lowland Humid Forest on Tree Species Diversity and Environmental Conservation

This study assessed the effects of exploitations in natural forest ecosystems on tree species diversity and environmental conservation. This was achieved by comparing tree species diversity and yield in an unlogged forest (Strict Nature Reserve) and a forest reserve where active logging is in progress in Ondo State, Nigeria. Eight plots (20 m × 20 m) were assessed in each site using systematic sampling techniques. All living trees with dbh >10 cm were identified, categorized into families with their diameter at breast height (dbh) measured in each plot. Shannon-Weiner and species evenness indices were used to assess and compare tree species diversity and abundance. The results show that the tropical humid forest is very rich in tree species, as a total of 54 different tropical hardwood species from 23 families were encountered in both forest types. There were 46 species distributed among 21 families in the unlogged forest and 24 species in 14 families in the logged forest. Shannon-Weiner diversity index of 3.16 and 3.03 and evenness index of .83 and .81 were also obtained for the unlogged and logged forest, respectively. Every variable computed had a higher value in the unlogged forest relative to the logged forest. In the unlogged forest, the species with the highest number of occurrence was Mansonia altissima A. Chev. (80 stems/ha). Caesalpinoidae and Sterculiaceae families had the highest number of species (6). In the logged forest, Triplochiton scleroxylon K. Schum. (18 stems/ha) had the highest frequency and Caesalpinoidae family has the highest number of species (4). The study concludes that exploitation has affected species diversity in the ecosystem and subsequently, the roles of trees in environmental conservation are affected.     

Physicochemical and kinetic characteristics of rhodanese from the liver of African catfish <Emphasis Type="Italic">Clarias gariepinus</Emphasis> Burchell in Asejire lake

Two forms of rhodanese were purified from the liver of Clarias gariepinus Burchell, designated catfish rhodanese I (cRHD I) and rhodanese II (cRHD II), by ion-exchange chromatography on a CM-Sepharose CL-6B column and gel filtration through a Sephadex G-75 column. The apparent molecular weight obtained for cRHD I and cRHD II was 34,500 ± 707 and 36,800 ± 283 Da, respectively. The subunit molecular weight determined by sodium dodecyl sulphate–polyacrylamide gel electrophoresis was 33,200 ± 283 and 35,100 ± 141 Da for cRHD I and cRHD II, respectively. Atomic absorption spectrophotometric analysis revealed that cRHD II contained a high level of iron (Fe), which presumably was responsible for the brownish colour of the preparation. In contrast, no Fe was identified in cRHD I, and its preparation was colourless. Further characterization of cRHD II gave true Michaelis–Menten constant (K _m) values of 25.40 ± 1.70 and 18.60 ± 1.68 mM for KCN and Na₂S₂O₃, respectively, an optimum pH of 6.5 and an optimum temperature of 40°C. The Arrhenius plot of the effects of temperature on the reaction rate consisted of two linear segments with a break occurring at 40°C. The apparent activation energy values from these slopes were 7.3 and 72.9 kcal/mol. Inhibition studies on the cRHD II enzyme showed that the activity of the enzyme was not affected by Mn²⁺, Co²⁺, Sn²⁺, Ni²⁺ and NH₄ ⁺, but Zn²⁺ inhibited the enzyme considerably.