Abstract: Agriculture has done more damage to nature than any other human activity, and yet food production could need to be doubled by the middle of this century. As agricultural land is expanded and intensified, critical thresholds in the loss of natural habitats are crossed. This loss of non-crop habitats can have negative feedback on crop production,because it can cause a loss of “ecosystem services” that support and regulate crop production, such as the pollination of crops by bees ...
Abstract: Oviposition decisions are a prominent example of behaviour directly affecting the fitness,abundance, distribution, and population dynamics of holometabolous insects. Due to eggs being immobile and adult insects often not practicing biparental and/or maternal care, gravid females, when ovipositing, should select substrate(s) that maximise fitness of their offspring.Studies have revealed that this selection is influenced by biotic (intra and interspecific competition, parasitism, lar...
Abstract: Grain legumes are among the key economical crops widely grown in western and eastern Africa as important sources of food and animal fodder. However, the production of grain legumes in Kenya is seriously affected by a complex of insect pests particularly thrips. Yield losses of 20 to 100% have often been reported in some areas. The bean flower thrips (BFT), Megalurothrips sjostedti is considered to be the most important thrips pest of grain legumes. Chemical control is still the mai...
Abstract: Small-scale farmlands are dynamic systems crucial to the food-security and livelihoods of more than two billion people and there is political pressure in many developing nations to consolidate and expand small farms into larger units of management. This could have consequences for agro-ecosystem processes and the ecosystem services and disservices that regulate crop production. This thesis aims to highlight and address these issues in smallholder farming landscapes, which are poorl...
Abstract: Chapter 18 IntroductionSuccess in malaria vector control in recent years has been attributed largely to the widespread distribution and utilization of long lasting insecticide-treated nets (LLINs) and indoor residual spraying (IRS)(WHO, 2019). The disruption of contact between the human host and the vector remains a very effective mechanism of controlling mosquito-borne diseases when applied in combination with other tools such as effective diagnosis, prevention of mother to child ...
Abstract: The invasion by Striga in most cereal crop fields in Africa has posed an acute threat to food security and socioeconomic integrity. Consequently, numerous technological and research developments have been made to minimize and even control the Striga impacts on crop production. So far, efforts to control Striga have primarily focused on the manipulation of the genetics of the host crops, as well as understanding the phenological and physiological traits, along with the chemical comp...
Abstract: Maize is the most widely grown cereal crop worldwide, and is the most important staple crop in sub-Sahara Africa. The spotted stemborer, Chilo partellus (Swinhoe) (Lepidoptera:Crambidae) is considered among the most important pests of maize and the damage it causes may result in yield losses of up to 88%. Previous studies showed that plants damaged by herbivores release huge amounts of volatile compounds, known as herbivore-induced plant volatiles (HIPVs) into the environment, whic...
Abstract: Globally, orange is one of the major fruit crops contributing to nutrition and monetary income. False codling moth (FCM), Thaumatotibia leucotreta, is one of the major constraints of orange production. Before this study, little was known regarding the bioecology of FCM in orange and vegetables in Kenya and Tanzania and the potential use of dry conidia of entomopathogenic fungi for control of T. leucotreta moths has not been tested. There is also no IPM strategy available for FCM in...
Abstract: Tephritid fruit flies are among the most destructive pest species of fruits and vegetables in many regions of the world. Apart from high losses in yield, tephritid fruit fly pests pose great socioeconomic and ecological challenges as well as demand effective measures to curb infestation which can be costly. Among currently used management options are the use of chemical insecticides, behavioral, genetic, cultural and biological approaches. However, no single method or combination o...
Abstract: To investigate the effects of variation in host quality on densities and sizes of three levels of consumers, a cabbage-aphid-parasitoid foodweb was analyzed. Three close related cabbage populations were studied: Brassica oleracea var. gemnifera cv. Cyrus, a feral Brassica oleracea and a wild cabbage type Old Harry as source of variation in host plant quality. A field experiment were established in Wageningen, The Netherlands to measure the effects on densities of herbivores. Aphids...
Abstract: The SolarMal project on Rusinga Island, Western Kenya, aims to eliminate malaria by reducing the mosquito population, using a new developed mosquito trap which will be installed at all households on the island. The effect of the installed traps is monitored by sampling mosquitoes from randomly selected selected households on the island during the whole duration of the project. This thesis project aims to support the SolarMal project by performing spatial analysis to the distributio...
Abstract: Information on pesticide residue occurrence in hive products is scanty or lacking yet it is important so as to safeguard human health from effects of pesticides. The aim of the study was to identify and quantify neonicotinoid residues in hive products. The study was undertaken for 6 months between (March-August, 2015) at Kiambu and Nairobi Counties. The objectives of the study were to find out the pesticides used in the cultivation of crops, the frequency of use and the concentrati...
Abstract: A study on mechanisms used by subsistence farmers to cope with climate variability and change was conducted in the Taita Hills, Kenya from January 2014 to March 2015. Household surveys together with key informant interviews were used to collect data to assess farmers’ use of crop diversification as a strategy to cope with climate variability and change. Further there was an assessment of past crop records in relation to weather and climate data in the area. The study then assesse...
Abstract: In the past 3 decades, arboviruses have become a major cause of re-emerging epidemic diseases in the world. Amongst the arboviruses, dengue and chikungunya fevers which are transmitted by Aedes spp have become more prevalent and have spread far beyond traditional areas of distribution - mainly in Africa and Asia - to cause severe morbidity, mortality, and economic harm. Currently control of these diseases solely depends on vector control as there is no treatment or vaccine. This ca...
Abstract: Malaria control strategies that target adult mosquitoes are challenged by the emergence of insecticide resistance and behavioral changes of vectors. The conventional approach of applying larvicides is limited by high operational costs and inadequate knowledge of mosquito breeding habitats especially in rural African communities. This study developed a potential mosquito contamination site, assessed the potential of adult female Anopheles gambiae s.s to pick up fluorescent dye and a...