Early growth, survival and litter size in Ethiopian Horro sheep

(South African J of Animal Science: 2000, 30, Supplement 1: 1-3

Classical double-layer atoms: artificial molecules

The groundstate configuration and the eigenmodes of two parallel two-dimensional classical atoms are obtained as function of the inter-atomic distance (d). The classical particles are confined by identical harmonic wells and repel each other through a Coulomb potential. As function of d we find several structural transitions which are of first or second order. For first (second) order transitions the first (second) derivative of the energy with respect to d is discontinuous, the radial position of the particles changes discontinuously (continuously) and the frequency of the eigenmodes exhibit a jump (one mode becomes soft, i.e. its frequency becomes zero).Comment: 4 pages, RevTex, 5 ps figures, to appear in Phys.Rev.Let

New pseudotagmic genus of acaricaline mites (Eriophyidae, Acaricalini) from a South African palm Hyphaene coriacea and remarks on lateral opisthosomal spines and morphology of deutogynes in Eriophyoidea

A new genus, Tumescoptella n. g., with two new sympatric species Tumescoptella aculeata n. sp.and T. rotundiscuta n. sp., was found on the indigenous South African palm Hyphaene coriacea, Lala palm. Both species are described and illustrated with the aid of conventional light microscopy, confocal laser scanning microscopy and low temperature scanning electron microscopy. Additionally, a new record of Tumescoptes dicrus Meyer collected from Phoenix reclinata(Arecaceae), near Kirstenbosch Gardens (Cape Town, South Africa), is reported. Morphologically the Tumescoptella n. g. is most similar to Tumescoptes Keifer, but possesses a more reduced chaetome and more derived pseudotagmosis. Pseudotagmosis is one type of body consolidation in vagrant eriophyoids, realized through the formation of dorsal opisthosomal plates, pseudotagmata. Along with previously described pseudotagmata (prodorsum, cervix, postprodorsum, superpostprodorsum, pretelosoma, and telosoma), a new term, anteroscutum, is proposed for the complex pseudotagma formed as a fusion of the three anterior pseudotagmata (prodorsum+cervix+postprodorsum) in several phyllocoptine mites from palms. An anteroscutum is present in monotypic Scolocenus Keifer from coconut and in the new genus Tumescoptella n. g. Protogyne females of Tumescoptella n. g. have uncommonly large lateral opisthosomal spines. Along with tiny spinules, triangular cuticular plates, band-shaped processes, and areas of thickened cuticle, the lateral spines belong to a common group of serial derivatives of dorsal opisthosomal annuli. We give a brief review on variation of spine-like structures across taxa of Eriophyoidea and their morpho-functional evaluation. Contrary to protogyne females, deutogyne females of T.aculeata n. sp. lack lateral spines, and they possess a smoother topography of the anteroscutum. Morphological similarity of these deutogynes with mites of the less transformed genus Tumescoptesis in accordance with a previous hypothesis on the possible correspondence of deutogyne morphology to that of an ancestral taxon. Two hypotheses on the origin of the presumably monophyletic group of Tumescoptes-like phyllocoptines (TP) from palms, comprising genera Scolocenus, Tumescoptella n. g., Tumescoptes, and Pseudotagmus, are proposed based on morphological similarity with two groups of eriophyoid genera: (a) pseudotagmic genera associated with aboriginal Asian dicotyledonous tropical trees, and (b) South American phyllocoptines from arecoid palms.Light microscopy investigation of the mite samples from Africa was supported by research projects of ZIN RAS (#АААА-А17-117030310209-7). CLSM studies were performed at the Research park of St. Petersburg State University in the Center for Molecular and Cell Technologies (IAS 1.53.917.2016, project #109-9164) and Center for Microscopy and Microanalysis (IAS 1.52.1424.2016, project #112-8186). LT-SEM studies were performed at the Laboratory for Microscopy and Microanalysis, University of Pretoria, South Africa.The field survey to collect eriophyoid mites on Hyphaene palm species was funded by the South Africa Department of Science and Technology grant to the Agricultural Research Council in South Africa.https://www.biotaxa.org/saaam2019Forestry and Agricultural Biotechnology Institute (FABI

Leptospira interrogans serovar pomona associated with abortion in cattle : isolation methods and laboratory animal histopathology

Leptospira interrogans serovar pomona was successfully isolated from cattle urine in the western Transvaal after an abortion storm had occurred. Direct inoculation of EMJH medium proved the most successful method. The selective agent, 5-fluorouracil, was most effective in controlling contamination when used at the 0,4 mg/ml level. The strain isolated was pathogenic in hamsters, but specific lesions and the leptospirae were seen only where overwhelming infection occurred.The articles have been scanned in colour with a HP Scanjet 5590; 600dpi. Adobe Acrobat XI Pro was used to OCR the text and also for the merging and conversion to the final presentation PDF-format

Evidence that Quadrastichodella nova (Hymenoptera: Eulophidae) is the only gall inducer among four hymenopteran species associated with seed capsules of Eucalyptus camaldulensis (Myrtaceae) in South Africa

Three chalcidoid wasp species, Megastigmus zebrinus Grissell (Torymidae), Quadrastichodella nova Girault (Eulophidae) and Leprosa milga Kim & La Salle (Eulophidae), have each been described independently as gall inducers associated with Eucalyptus species (Myrtaceae). The finding that at times they emerge together from seed capsules of river red gum (Eucalyptus camaldulensis Dehnhardt) collected at the same site in South Africa, cast doubt on the accuracy of these earlier interpretations. The current study examined the gall inducing abilities of each of the three wasp species. During geographical surveys, all three species coexisted in seed capsules at 16 of the 61 sites sampled. A study of the seasonal emergence pattern of the three species, together with a fourth, locally abundant gall associate, Aprostocetus sp., showed that Q. nova and L. milga emerge during early summer, while the remaining two species emerge in smaller numbers throughout the year. Oviposition trials on sleeved branches of E. camaldulensis, from which all insects had previously been excluded, verified that Q. nova had the ability to induce galls, while both M. zebrinus and L. milga failed to do so. Only one type of gall of characteristic structure was encountered, which repudiates the possibility of a second gall inducer, and no indication of inquilinism was found. Megastigmus zebrinus, L. milga and Aprostocetus sp. are thus more likely to be parasitoids.DNA sequences were obtained for the adults of all four these species. By matching the DNA of identified adults with that of juvenile hymenopterans in the galls, it was confirmed that all four hymenopterans species developed within the seed-capsule galls of E. camaldulensis. Regrettably, this technique failed to give a clear indication of the exact host relationships between the various gall inhabitants. By dissecting seed capsules at different stages of gall development, the origin of the gall was proven to be in the placenta of one of the locules of a flower bud, and not in a seed or ovule, as previously reported.The Agricultural Research Councilhttp://reference.sabinet.co.za/sa_epublication/entohttp://www.entsocsa.co.za/Publications.htm2017-03-30am201

A proposed classification of invasive alien plant species in South Africa: Towards prioritising species and areas for management action

Many invasive alien plant species in South Africa are already well-established and cause substantial damage, while scores of others are at the early stages of invasion (only recently introduced and/or entering a phase of rapid population growth). Management programmes must target well-established invaders, but must also give appropriate attention to emerging problems. Protocols for objectively prioritizing species in the two groups for management action are lacking. To this end, we describe the objective derivation of two lists of invasive alien plants in South Africa, using available quantitative data and expert knowledge on current patterns of distribution and abundance, life-history traits, and (for emerging invaders) estimates of potential habitat. ‘Major invaders’ are those invasive alien species that are well-established, and which already have a substantial impact on natural and semi-natural ecosystems. ‘Emerging invaders’ currently have less influence, but have attributes and potentially suitable habitat that could result in increased range and consequences in the next few decades. We describe the derivation of lists that contain 117 major invaders (categorized into groups based on geographical range and abundance) and 84 emerging invaders (categorized into groups based on current propagule-pool size and potentially invasible habitat). The main lists, and groupings within them, provide a useful means for prioritizing species for a range of management interventions at national, regional and local scale

Gall thrips Acaciothrips ebneri (Thysanoptera: Phlaeothripidae) from Ethiopia, a promising biological control agent for prickly acacia in Australia

Based on climatic and plant phenotype matching, native-range surveys were conducted in Ethiopia to identify prospective biological control agents for prickly acacia, a serious weed of grazing areas in northern Australia. Surveys identified a gall thrips, Acaciothrips ebneri (Karny) (Thysanoptera: Phlaeothripidae), as a prospective biological control agent for prickly acacia, based on damage potential, field host range and geographic range in Ethiopia. The gall thrips was imported into a high security quarantine facility at the Ecosciences Precinct, Brisbane,Australia in December 2015 and host-specificity tests are in progress. If approved, the gall thrips would be the first gall insect to be released against prickly acacia in Australia.The Meat & Livestock Australia, Rural Industries Research & Development Corporation and Rural Research & Development for Profit Programme of the Australian Government (Department of Agriculture and Water Resources).http://www.journals.co.za/content/journal/entohttp://www.bioone.org/loi/afen2020-04-01am2018Forestry and Agricultural Biotechnology Institute (FABI

Topological Defects and Non-homogeneous Melting of Large 2D Coulomb Clusters

The configurational and melting properties of large two-dimensional clusters of charged classical particles interacting with each other via the Coulomb potential are investigated through the Monte Carlo simulation technique. The particles are confined by a harmonic potential. For a large number of particles in the cluster (N>150) the configuration is determined by two competing effects, namely in the center a hexagonal lattice is formed, which is the groundstate for an infinite 2D system, and the confinement which imposes its circular symmetry on the outer edge. As a result a hexagonal Wigner lattice is formed in the central area while at the border of the cluster the particles are arranged in rings. In the transition region defects appear as dislocations and disclinations at the six corners of the hexagonal-shaped inner domain. Many different arrangements and type of defects are possible as metastable configurations with a slightly higher energy. The particles motion is found to be strongly related to the topological structure. Our results clearly show that the melting of the clusters starts near the geometry induced defects, and that three different melting temperatures can be defined corresponding to the melting of different regions in the cluster.Comment: 7 pages, 11 figures, submitted to Phys. Rev.