Identification of new Sub-Saharan African begomoviruses and Bemisia tabaci species boundaries

Fecha de lectura de Tesis Doctoral: 29 de noviembre 2019Los begomovirus (género Begomovirus, familia Geminiviridae) son un grupo extremadamente exitoso de virus de ssDNA que causan enfermedades devastadoras a cultivos importantes en las zonas tropicales y subtropicales de todo el mundo. En 2015 se llevó a cabo un muestreo en Uganda con el objetivo de recolectar y caracterizar los begomovirus presentes en plantas sintomáticas, principalmente no cultivadas. Se amplificaron genomas completos de begomovirus y ADN satélites asociados mediante amplificación por círculo rodante (RCA) que se clonaron y secuenciaron. En base a los análisis de secuencia, en este estudio se han caracterizado cinco nuevas especies de begomovirus y un nuevo betasatélite: i) vernonia crinkle virus y vernonia crinkle betasatellite infectando a Vernonia amygdalina (familia Compositae), ii) desmodium mottle virus infectando a Desmodium sp. (Fabaceae) y iii) ocimum yellow vein virus, ocimum mosaic virus y ocimum golden mosaic virus infectando a Ocimum gratissimum (Lamiaceae). El análisis filogenético y la organización genómica del ADN-A de estos nuevos begomovirus mostraron que pertenecen al grupo filogenético Old Word, con la excepción de DesMoV que pertenece al grupo de los legumovirus. En este trabajo también se investigaron las interacciones de apareamiento entre poblaciones de mosca blanca de Bemisia tabaci que infestan yuca (Manihot esculenta) en África subsahariana (SSA) e Ipomoea indica en España. B. tabaci es un grupo de más de 40 especies crípticas que incluyen algunas de las plagas de insectos más devastadoras y vectores de virus de plantas en todo el mundo, incluidos los begomovirus. Se realizaron cruces recíprocos para examinar las interacciones de apareamiento dentro y entre especies putativas del complejo B. tabaci y se confirmó que las poblaciones de mosca blanca SSA2 de España se cruzaron con SSA2 y SSA3 del África subsahariana y producen descendencia fértil, lo que sugiere que estas poblaciones pertenecen a la misma especie biológica

The Seasons

At first it is easy to accept the coming of the dry season, for the greenness of things takes a while to give way to the dust. But with time it is not so easy to shrug and simply say that the coming of the dry season after the rainy one is as normal as night coming after day. Such indifference is impossible when the dry season has truly arrived and has sunk its claws into people and things. The only good thing about the land then is the sudden, wild thought of leaving, to leave never to come back but go as far as your legs can carry you, to some place where the drought is merely a thing to be told about

The impact of globalization on Maasai culture : with special focus on the Ilmuran age-group

Master's thesis in global studies. School of Mission and Theology, May 201

Acaricidal activities of extracts of Commiphora swynnertonii Burtt (Burseraceae), Melia volkensii Gürke, Turraea abyssinica Hochst., Turraea floribunda Hochst and Turraea cornucopia Styles & F. White (Meliaceae) against the brown ear tick Rhipicephalus ap

Acaricidal activities of extracts of Commiphora swynnertonii Burtt  (Burseraceae), Melia volkensii Gürke, Turraea abyssinica Hochst., Turraea floribunda Hochst and Turraea cornucopia Styles & F. White (Meliaceae) against the brown ear tick Rhipicephalus appendiculatus Neumann Extracts of the stem bark of Commiphora swynnertonii, the root bark ofTurraea abyssinica, T. cornucopia, T. floribunda and the ripened fruits of Melia volkensii were tested for acaricidal activities against nymphal and adult stages of Rhipicephalus appendiculatus in the laboratory. At a concentration of 10% (w/v), hexane and ethyl acetate extracts of C. swynertonii induced mean mortalities of 71% and 54% respectively, in two week old nymphs. A 10% (w/v) hexane extract was found to be as effective as the commercial acaricide Triatix against the twoweek- old nymphs. Extracts of T. cornucopia, T. abyssinica and M. volkensii induced no mortality in nymphs and adults, but suppressed oviposition capacity during the first day. On the other hand, 500µl of 10% (w/v) methanol extracts of T. cornucopia and T. floribunda delayed attachment by adult females of R. appendiculatus on the rabbit ears, engorgement and hatchability of their eggs.Keywords: acaricidal, activity, plant extracts, Burseraceae, Meliaceae,Rhipicephalus appendicullatus

Antifeedant activity of twenty six plant extracts and pure compounds from the root bark of Toddalia asiatica (L) (Rutaceae) against the anomalous emperor moth Nudaurelia belina (Saturnidae)

The antifeedant activity of petroleum ether (PE) (40-60%) extract of the root bark of T. asiatica and twenty five other plant extracts was investigated against the anomalous emperor moth N. belina. The petroleum ether extract of stem bark of Albizia anthelmintica, leaves of Cassia occidentalis, Balanites aegyptica, seeds of Cucumis sativaus, root bark of T. asiatica, root bark of Celtis durandii, B. aegyptica and whole plant of Cisus quadrangularis were found to be active against N. belina at a concentration of 1% w/v in a modified leaf disc method. Also, methanol extracts of the root bark of A. muricata and Eucalyptus spp were found to be active against N. belina at a concentration of 1% w/v. Three cumarius; dihydrotoddanol, toddanol and toddalactone and the alkaloid dihydrochelerynthrine isolated from the PE extract of the root bark of T. asiatica exhibited antifeedant activity at as low as 0.05% w/v. Toddaculine and toddanone which were also isolated from the P.E. extract had no activity at 0.05% w/v.Keywords: Antifeedants, Toddalia asiatica, Rutaceae, Nudaurelia belina, Saturnida

Farmer-identified indigenous fruit tree with suitable attributes for the semi-arid Northern Province of South Africa

The study describes different research techniques used to gather useful information to assist smallholder farmers in making important decisions on the identification and selection of an indigenous fruit tree for domestication and commercialisation. The study demonstrates how action research brings together farmer-researcher actors into rural development in an interaction designed to address and find a solution to a problem as identified by farmers. In the end an indigenous technology/product is selected, that fits well into smallholder farming systems. The indigenous fruit tree, Mmupudu (Mimusops zeyheri; English = Transvaal red milkwood; Afrikaans = Moepel) was top - ranked as having favourable environmental, economic and nutritional attributes for conditions under which rural communities in the semiarid Northern Province of South Africa live