INTRODUCTION Sorghum bicolor Moench is one of the main staple food grains. The cereal forms part of staple food of the world's poorest people, particularly in the Semi-Arid Tropics (SAT). Elsewhere, especially in the developed world sorghum is used mainly as a fodder crop. The crop is grown on 42 million hectares in different parts of the world (FAO, 1980). Over 55% of the world’s sorghum production is in the SAT of which Africa and Asia contribute 65% (Swindle, 1982). In East Africa, sorgh...
Abstract: Stingless bees are important pollinators contributing significantly to biodiversity and food security. Stingless bees produce honey that has high medicinal value that fetches higher prices compared to the honey produced by honey bees (Apis mellifera). However,identification and classification of Afrotropical stingless bees, which is key and important for their domestication, still remains ambiguous and solely reliant on the use of morphological features. In this study, an integrati...
Abstract: This thesis describes the results of a study to assess the effect of ethnobotanical products on the behaviour of the brown ear tick Rhipicephalus appendiculatus, the main vector of East Coast fever in sub-Saharan Africa. Ethnoknowledge of the Bukusu people in western Kenya on tick control and management was evaluated to identify plants that affect livestock ticks, using participatory action research approaches. More than 150 plant species spread over 110 genera and 51 families were...
Abstract: In Locusta migratoria, vitellogenin (Vg) synthesis is normally induced by juvenile hormone (JH) only in adult females. Larval and adult female and male locusts were tested for inducibility of Vg synthesis by the synthetic JH analog, methoprene. While fourth and fifth larval stages of both sexes could be induced to synthesize Vg, adult males could not. Quant i tati ve assays showed the relative response in the order: adult female > fifth instar female > fifth instar male. Dur i ng t...
Abstract: Lepidoperan stemborers are a major constraint to increasing the production of maize and sorghum under subsistence farming conditions in sub-Saharan Africa. Classical biological control is considered as the most cost-effective form of pest management but it has not attained the desired success rate. It has been postulated that one major reason for the failures in classical biological control is related to the genetic diversity of released_ individuals of natural enemies. The aim of ...
Abstract: Liriomyza (Diptera: Agromyzidae) leafminers are pests of economic importance to the production of horticultural crops in East Africa. In the scope of a classical biological control program in East Africa, two parasitoids Halticoptera arduine (Walker) (Hymenoptera: Pteromalidae) and Chrysocharis flacilla Walker (Hymenoptera: Eulophidae) were introduced from Peru. This dissertation aims to assess the performance and impact of the parasitoids in biological control of Liriomyza leafmin...
Abstract: Scanty information is available concerning the identity of the major pests of amaranth and African nightshades in Kenya and associated damage. The natural enemies of these pests have also not been studied in detail. In this PhD study, field survey to identify the major pests of amaranth and nightshades, their abundance, distribution, and damage in six regions in Kenya was conducted. The natural enemies for these pests present in the amaranth and nightshade fields in these regions w...
Abstract: Although it is widely accepted that plant resources play an important role in the biology of mosquito species, the preferred mosquito host plants in the natural habitats remain largely unknown. The persistence of mosquito-borne diseases and the re-emergence of others such as Zika have created the need for novel control strategies with plant feeding becoming a new focus for such strategies. Effective deployment of these new tools requires an accurate identification of preferred host...
Abstract: Malaria continues to be a major cause of morbidity and mortality in Kenya, with the transmission caused by mainly Anopheles gambiae funestus complexes. It is a serious threat to the social and economic advancement of the country. In this study, Field and laboratory studies were used to examine the primary factors responsible for regulating the aquatic stages of malaria vectors and the abundance and diversity of no-mosquito invertebrates in rice fields. The temporal and spatial prod...
Introduction: In Africa, there are two well known subspecies of the desert locust: the sahara subspecies, Schistocerca gregaria gregaria (Forskal) and the southern west subspecies, Schistocerca gregaria flaviventris (Burmeister). The sahara desert area, which is invaded by the S.g. gregaria is divided into three main regions: the north central region, south central and western regions.
Abstract: The sweet potato butterfly (Acraea acerata Hew.) has become an important pest on sweet potato in Southern Ethiopia in the last two decades. This thesis deals with its ecology and economic importance in Southern Ethiopia.The insect is indigenous to this area where it feeds on both native wild lpomoea species and the introduced sweet potato (L batatas). However, its perfonnance was better on the new host, sweet potato. The small A. acerata populations on the scattered patches of the ...
Abstract: Pathological potential of the fungus Beauveria bassiana Balsamo on the desert locust Schistocerca gregaria Forsk was evaluated with an aim to develop a mycoinsecticide as a supplement to the persistent chemical insecticides used for desert locust control in order to min imize the pollution in agroecosystems. Conidial suspension of B. bassiana when topically applied to locusts was found to be effoctive under 27.5 ± 2.50°C and 90% RH. Comparative stage susceptibility studies showed...
Abstract: D’après la FAO, il faudra nourrir 9 milliards de personnes en 2050 ce qui équivaudrait à augmenter de 70% la production actuelle. Une manière simple d’augmenter la production serait de limiter les pertes de rendement et de récolte en luttant contre les insectes. Il faudra donc produire plus mais il faut produire mieux. Les insecticides ont été et sont largement utilisés mais avec l’apparition de résistances, la pollution de l’environnement et l’impact sur la sant...
Abstract: Banana (Musa spp.) is an important food crop of the humid tropical lowland areas of the world. Banana production is beset by several problems, related to crop husbandry, selection of planting material, soils, diseases, and pests. Although more than 25 borers have been recorded on banana, the banana weevil Cosmopolites sordidus (Germar) (Curculionidae) is regarded as the major contributor to the general loss in plant vigour and yield. However, some banana cultivars have been found t...
Abstract: Host-seeking is an important component of mosquito vectorial capacity on which the success of the other behavioural determinants depends. Blood-seeking mosquitoes are mainly guided by chemical cues released by their blood hosts. This thesis describes results of a study that determined the effect of microorganisms – host skin bacteria as well as malaria parasites – on host-seeking behaviour of female Anopheles gambiae sensu stricto and An. arabiensis in Homabay county, western K...