PHD-Department of Zoologial Sciences

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Anopheles larval productivity and diversity in Mwea irrigation scheme, Kirinyaga district, Kenya
(2011-11-08) Mwangangi, Joseph Mumo
The use of irrigation to flood agricultural land during rice cultivation has over the years been associated with an increase in the number of disease vectors and corresponding increase in health burden due to malaria and other vector and waterborne diseases. In this study, field and laboratory studies were used to examine the primary factors responsible for regulating the aquatic stages of malaria vectors in a rice agro-ecosystem prior to implementation of a larval control programme. The objective of this study was to determine the environmental and agricultural factors that regulate malaria vector productivity and diversity in Mwea Irrigation Scheme, Kirinyaga district, Kenya. The study was conducted in 3 villages representing planned (Mbui Njeru), and unplanned rice cultivation with varying amount of land under rice (Kiamachiri and Murinduko). The physico-chemical variables were measured using different field based hand held equipments or visual assessment. Experimental plots were used to closely monitor the factors associated with Anopheles larval densities in the rice fields. A total of 29,252 immature stages of anopheline mosquitoes were collected in the three villages comprising of'78.23% (n = 22,885) early instars, 10.91% (n = 3,192) late instars and 10.85 % (n = 3,173) pupae. Anopheles gambiae s.l. was the most abundant and was found in all habitats that were positive for late anopheline instars in the 3 villages. Larval abundance was significantly higher in Murinduko compared to the other villages (F(2, 182) = 38.685, p< 0.01). Rainfall was positively associated with Anopheles gambiae s. l. larval abundance in Kiamachiri (r = 0.759) and Mbui Njeru (r = 0.602) but negatively associated in Murinduko (r = - 0.267). Multiple logistic regressions showed Anopheles larval density to be significantly associated with many interrelated biotic and abiotic variables including presence of other invertebrates, percentage Azolla cover, distance to nearest homestead, water turbidity, water temperature, conductivity, pH, and water depth. Anopheles productivity from different habitat types showed that paddies had most emergent mosquitoes (n = 143) followed by marshes (n = 65). Succession of Anopheles species was evident with An. gambiae colonizing the paddies throughout the rice growth cycle with peaks during the early stage of rice growth while An. rufipes and An. coustani occurred during the late vegetative stages. Larval densities were significantly higher at the centre of the paddy compared to the periphery during the transplanting period (F (1,166) = 4.809, P = 0.030) but the difference was not significant during the tillering period (F (1,362) = 0.037, P = 0.848). The survivorship of immatures in the paddies showed that there was 98.26% mortality of larvae. In conclusion, rice paddies and associated canals are the most productive habitats types throughout the year while peridomestic habitats are important during the long and short rains. The results further indicate that several biotic and abiotic factors interact to regulate Anopheles larval densities in aquatic habitats. These findings demonstrate the need to target larvicidal application in the entire paddy between transplanting and tillering stages in order to achieve effective larval control.
Anthropogenic Impacts on Distribution and Abundance of Mountain Catfish (Amphilias Uranoscopus, Pfeffer, 1889) and Other Fishes, in the Sagana and Thego Streams, Nyeri, Kenya
(Kenyatta University, 2019-04) Odhiambo, Charles Oduor
The clearance of forest for agriculture, settlement and grazing has had some of the most widespread human impacts on natural ecosystems globally. In Kenya large tracks of indigenous forests continue to be cleared to give way for human settlement and exotic tree plantations. The catchment on the slopes of Mt. Kenya has experienced such major losses that have affected the aquatic ecosystem. The objective of this study was therefore to document the extent of impact of anthropogenic activities on the distribution, abundance and population sizes of the mountain catfish (Amphilius uranoscopus Pfeffer, 1889) and other fish species along two second order tropical forested streams, Sagana and Thego on the slopes of Mt. Kenya. This study was done from June 2016 through May 2017. Fish samples were caught using an electrofisher and recorded for distribution, population sizes, reproductive strategies and feeding habits. Water samples for physiochemical parameters were determined in situ and a socio-economic survey of the riparian community carried out using a structured questionnaire. The smallest sized catfish were caught in November 2016 at the Thego station T2 midstream while the largest specimen electrofished was a I9.0 cm fork length (92.19 female caught in the downstream station (T3) of the Thego. There was a significant difference (t-test, t : - 3.35; p:0.007) in the mean number of catfish caught per hour of electrofishing between the Thego stations (T2 and T3). A comparison between Catch per unit effort (CPUE) in Sagana and Thego (ANOVA, F : 6.82; p : 0.004) showed a significant difference in catches between the two streams. Results from this study shows that there have been major significant changes in the distribution patterns of both the native species as well as the salmonid species in the two streams and that the mountain catfish has expanded its territory while the introduced salmonid species zones have shrank or become thin. Catfish exhibited a wider food base overlapping with those of the other species such as rainbow trout, brown trout and barbus. The occurrence of the mountain catfish (Amphilius uranoscopus), Barbus sp. and Labeo sp. inthe midstream of the Thego and downstream of the Sagana and Thego, the absence of rainbow trout in the midstream of the Thego and the restriction of the brown trout to the near pristine reaches of the Sagana at an altitude above 2150 metres are some of the changes that have occurred since 1960s due to the impact of human settlement in the watersheds of streams in the slopes of Mt. Kenya. Major factors associated with the variation in catfish distribution and abundance among the study stations included increased temperatures, elevated stream water conductivity and decline in water discharge. These clearly show that the catfish population is likely to move fuither upstream in Thego than in Sagana unless urgent measures to control human related anthropogenic activities in Thego catchment area are adopted. This study supports the hypothesis that the mountain catfish distributional range will continue to expand at the expense of other fish species unless corrective measures are considered to control anthropogenic human driven settlement activities in the watershed of the Sagana and Thego. Management strategies should focus on the values of the society and recognize that the continuous expansion of mountain catfish home range is an indicator of environmental perturbation arising from change in landuse and increase in human activities.
Antiretroviral resistance and genetic diversity of human immunodeficiency virus among antenatal clinic respondents on nevirapine from North-Rift Kenya
(2011-07-11) Kiptoo, Michael Kibet
Mother-to-child transmission (MTCT) of HIV-1 is responsible for infection of hundreds of thousands of infants every year. It is estimated that 600,000 newborns are infected yearly worldwide, with MTCT accounting for 90% of these infections. Human immunodeficiency virus (HIV) can be transmitted from mother-to-child at various stages of pregnancy including in utero and intra partum. A number of feasible and effective interventions to reduce MTCT among women of child hearing age are available. These interventions include prevention of primary HIV infection, avoiding unwanted pregnancies among HIV positive women, reduction of transmission from infected mothers to infants during pregnancy, labour, delivery and breathfeeding through provision of voluntary counselling and testing (VCT) services, antiretroviral therapy (ART), safe delivery practices, and breast milk substitutes. However, these approaches are not always possible in resource-poor countries. The use of antiretroviral (ARV) drugs, in particular revirapine, zidovudine and zidovudine/lamivudine combination, has been studied in both developing and developed countries. Although these studies have shown reduction in transmission of HIV, concerns regarding the development of drug resistant strains have been raised. The Ministry of Health in Kenya has implement nevirapine regimen to reduce MTCT in the public health facilities. This study aimed to investigate drug resistance in an MTCT setting in Kenya. A total of 309 HIV seropositive pregnant women taking part in the prevention of mother of child transmission of HIV (PMTCT) programme in three hospitals, namely, South Nandi Hills, Kapsabet, and Kitale district hospitals were enrolled in this study. A structured questionnaire was used to collect demographic information. Venous blood was collected into vacutainer tubes containing EDTA as anticoagulant. The enumeration of T-lymphocytes was carried out by flow cytometry and viral load was determined by nucleic acid amplification. The proviral HIV DNA extracted from peripheral blood mononuclear cells (PBMCs) was sequenced to determine the drug resistance associated mutations and HIV-1subtypes. The significance of associations was investigated by chi-square test and odds ratios. The HIV prevalence among the pregnant women was 6.7% (309 of 4638). The majority (85%) of the women visiting the antenatal clinic were not aware of their HIV status. Sixty percent (60%) of pregnant women had a CD4 count of more than 350cells/mm3 . The HIV transmission rate was 6% (4 of 59 infants). Drug resistance associate mutations were detected as minor population except in one mother-child pair where major populations were found. Nevirapine drug resistance was detected in 19.4% (7 of 36) and 100% (3 of 3) of the women and infants tested respectively. Even though the women had not been exposed to nucleoside reversed transcriptase inhibitors (NRTIs), drug resistance associated mutations were detected in 8 mothers (22.2%) as minor populations. The major circulating HIV-1 subtype in North-Rift Kenya was identified as A1 (50% and 71.8%) based on the env (C2V3) and pol (RT) regions respectively. Human immunodeficiency virus type 1 subtypes D (12.8%), C (10.3%), A2 (2.6%) and G (2.6%) were also detected based on sequencing of the pol region. Drug resistance outcomes in mothers and infants should be considered as an important secondary end point in PMTCT assessment.
An assesment of the use of botanical extracts and pheromes for the off-host and on-host control of amblyomma variegatum tick
(2012-01-12) Toure, Alioune
The livestock tropical bont tick, Amblyomma variegatum Fabricius, is a pest of major economic importance in Africa where it is the vector of Cowdria ruminantium that causes Headwater, disease in cattle. Its control has relied mainly on commercial acaricides, which have many problems associated with, environmental pollution, development of resistant strains of ticks against acaricides and escalating costs. It has, therefore, become necessary to look for alternative methods of tick control, which are environmentally friendly, relatively cheap and which involve farmers directly. In this regard, the purpose of this study investigated the potential of pheromones in attracting ticks to a trap off-host and toxicating them with Neem products and the repulsion of ticks on-host using repellent plant. The use of pheromone components comprising Attraction-Aggregation-Attachment Pheromone (AAAP), 1-octen3-ol and 2,6-dichlorophenol to attract A. variegatum to traps containing botanical extracts on the vegetation was explored. The possibility of enhancing attraction of ticks to AAAP with 1-octen-3-ol and 2,6dichlorophenol was first investigated in a T-tube olfactometer in the laboratory. Whereas males were attracted to increasing proportions of 1-octen3-ol, females were repelled. A combination of 8 ng of 1-octen-3-ol with 1.1 mg of AAAP was adopted as an optimum for the attraction of both sexes, enhancing the attraction of ticks by 20% (p<0.0001). Unlike 1-octen-3-ol, 2,6dichlorophenol did not improve the attraction of A. variegatum in the laboratory (p=0.0667). In the field, the attraction of A. variegatum to different doses of AAAP+1-octen-3-ol combination from various distances was investigated. The longest distance from which ticks were significantly attracted was 7 m. The effects of continuous and intermittent release of carbon dioxide (CO2) on the performance of AAAP and 1-octen-3-ol in attracting ticks in the field were also investigated. The results showed that CO2 increased the range of attraction to 8 m and the continuous and the intermittent release of CO2 were not significantly different. The efficacy of traps treated with Neem Cake Extracts (NCE) and baited with AAAP, 1-octen-3-ol and CO2 was evaluated. The attraction to the traps as well as the modality of A. variegatum were significant (p<0.0001). The modality of attracted ticks was dependent on the concentration of NCE and the time of exposure. 98% modality was recorded for a concentration of 30% of NCE. The volatiles of two of the predilection feeding sites of A. variegatum (scrotum and lower dewlap) were tested against the odour of the ear. The scrotum and the lower dewlap were found very attractive to the ticks. The possibility of using plant extracts with repellent properties in reducing the number of ticks arriving and attaching at predilection sites was also investigated. Boscia senegalensis, Ocimum suave and Ocimum kilimandscharicum were tested as repellents. Ocimum kilimandscharicum was found to repel adult A. variegatum by 33%. This technology of using botanical traps baited with pheromones and CO2 as well as repellent plants could be improved and can be transferred to farmers where it can be incorporated in an Integrated Tick Management Strategy.
Assessment by performance attributes of indigenous egg parasitoids (hymenoptera: trichogrammatidae for biocontrol of african bollworm (helicoverpa armigera) in Kenya
(Kenyatta University, 2004-08) Kalyebi, A.
Trichogrammatid egg parasitoids are used extensively for the control of several lepidopteran pests in many areas of the world. They ar~he most promising biological control agents for inundative releases against the African bollworm Helicoverpa armigera, an injurious pest of several agricultural crops in Kenya and elsewhere in Africa. To enhance their potential impact in Kenya as well as eastern Africa, collections of indigenous species/strains (Trichogramma sp. nr. mwanzai and Trichogrammatoidea sp. nr. lutea from low altitude, Trichogramma sp. nr. mwanzai and Trichogrammatoidea sp. nr. lutea from medium altitude and Trichogramma bruni and Trichogrammatoidea sp. nr. lutea from high altitude) were made from different altitudes in Kenya and were evaluated following different criteria to select potential candidates for use against H. armigera. The major focus was their adaptation to a range of temperature and humidity \regimes. The criteria included functional response, lifetime parasitism and development and population growth characteristics at six temperatures (10, 15, 20, 25, 30 and 35°C) and two humidity regimes (40-50 and 70-80%). Preference of parasitoids for target pest and relative suitability for development among five lepidopteran hosts was also \ investigated, in addition to testing their capacity to attack H. armigera eggs occurring on two host plants (tomato and okra) in laboratory and field experiments. Functional response studies revealed that temperature affected parasitisation rates of the strains significantly, while relative humidity did not. Trichogrammatoidea sp.nr. lutea from high altitude, Trichogramma sp. nr. mwanzai from low altitude and T. sp. nr. mwanzai from medium altitude showed higher parasitism across the widest temperature range. There was no relationship between source altitude/climate and performance of the strains at the temperatures tested. Temperature and humidity interactions affected lifetime fecundity and progeny production. The highest parasitism at the two humidity levels was at 30°C for all the strains. The interaction of the two factors also affected adult longevity, which was longer at the lower than higher humidity. Survival followed a type l-survivorship curve at lower temperatures and a type III survivorship curve at the higher temperatures. These studies revealed that T sp. nr. mwanzai from both low and medium altitudes and T sp. nr. lutea from medium altitude appear as promising candidates for augmentative biocontrol of H. armigera. Temperature and humidity interactions also affected the population growth and development of parasitoids although temperature appeared to be more important. Developmental time was inversely related to temperature. The intrinsic rate of increase was found to increase with increasing temperature up to 30°C. The finite rate of increase also followed the same trend. The net reproduction rate also increased with increasing temperature up to a maximum at 30°C. Both net reproduction and intrinsic rate of increase were higher at the lower humidity. Temperature negatively affected generation time ofparasitoids regardless of the humidity level. Host acceptability studies showed that all the six species/strains did accept all the tested host species, although acceptance levels varied among strains and hosts. Most species/strains showed greater preference for noctuids over pyralids and yponomeutids. Suitability of hosts for progeny development varied from one species/strain to another. The different species/strains did not show significant differences in parasitising eggs of H. armigera when placed on two host plants, namely tomato and okra. From these studies, T. sp. nr. mwanzai CM), T. sp. nr. mwanzai CL) and T. sp. nr. lutea (M) offer great potential as candidates for augmentative biocontrol of H. armigera in Kenya.
Assessment of Mangrove Phenology and the Role of Insect Pollinators in Fruit Production at Nyeke and Michamvi Mangrove Forests, Zanzibar
(Kenyatta University, 2016-05) Ali, Abdalla Ibrahim
Mangrove forests are evergreen estuarine and open systems which receive nutrients, fresh water and sediments from terrestrial environments. They vary both in their salinity tolerance and the degree to which salinity may be necessary to maintain their growth and competitive dominance. Mangroves grow throughout the tropics wherever the average monthly minimum temperature is at least 200C. The ecological importance of mangroves are due to the ecosystems’ ability to maintain marine life, their high productivity and role in supplying organic material to other coastal marine ecosystems as reported by many studies. Mangroves trees have been proven to be very important in the mangroves ecosystem. Anthropogenic activities have been shown to be the primary cause of mangrove depletion worldwide. Rising mangroves forest destruction has negatively impacted on pollinator diversity and fruit set significantly. However, little is known about the magnitudes of these issues in East Africa. This research was therefore designed to assess diversity and abundance of mangrove insect pollinators and their role in fruit set in four mangrove species at Nyeke and Michamvi mangrove forests, Zanzibar. The study was conducted in two mangrove sites in South region of Zanzibar, Nyeke mangrove forest located between 60 19’ and 60 24` S and 390 25` E, and Michamvi mangrove forest located between 60 14’ S and 390 49’ E. The distance between the two sites is approximately 25km. Four mangrove species which are pollinated by insects (Rhizophora mucronata, Bruguiera gymnorhiza, Ceriops tagal and Avicennia marina) selected from Nyeke and Michamvi mangroves forests were used in the study. The reproductive phenology, reproduction relationships of mangroves, pollinator species diversity and richness, and effect of pollination on fruit set were investigated. The study found that reproductive phenology varied among species and sites. The peak fruit set varied among species and sites. There was a positive relationship between temperature and reproduction but not with rainfall and relative humidity. In both sites the findings showed a weak relationship between fruit set and number of fruits. The study also revealed that increase in number of insect flower visitors and visits did not result in increased fruit sets. However, increase in number of flowers increased the number of insect flower visitors and visits. A total of 18029 insect flower visitors representing 70 species in 7 orders and 40 families were observed visiting flowers of the four mangrove species in both sites. Family Apidae of the order Hymenoptera was the most common and insects of this order were found in all four mangroves species. Apis mellifera was the most dominant flower pollinator for Bruguiera gymnorhiza, Ceriops tagal and Avicennia marina. Hypotrigona gribodoi was predominantly found on RM and is potentially the flower pollinator of this species. Higher number of Apis mellifera 721 (32.2%) was recorded in Bruguiera gymnorhiza at Nyeke site. Bagged experiment that prevented most pollinators accessing the flower, showed a high percentage of flower abortion and lowest fruits produced than other treatments in this study. A. marina had confirmed lower fruit set compared to the other species. Pollen Supplement (PS) (hand cross pollination) produce higher percentage of fruits set and fruits in some mangroves species in both sites. This not only shows that additional pollen enhances fertilization but also that pollination is necessary for fruit production. The study concludes that, in depth research on various variables of mangroves including inventory of pollinators, biodiversity, social economic significance, potential threats and phenology for other species and climate alteration are important for strengthen biodiversity conservation and mitigation.
Behavioural responses of rhipicephalus appendiculatus neumann 1901 and rhipicephalus evertsi, neumann 1987 (Acari: ixodidae) to host and non-host semiochemicals
(2012-05-02) Noel, Sika Fra Kutua
On-host observations and laboratory behavioral assays were undertaken to investigate the role played by semiochemicals in the location of feeding sites by unfed adults of Rhipicephalus appendiculatus Neumann and Rhipicephalus evertsi Neumann. The semiochemicals were derived from the host ear and anal region of bovine cattle and from conspecifics. The potential of host-derived allomones from unpreferred feeding sites and extracts of a tick repellent plant, Ocimum suave Willd as disrupting factors to on-host orientation by the two tick species to their target sites were also assessed. Orientative behaviour of R. appendiculatus on host was characterized by stereotyped sequences of behaviours, which included stationary/scanning phase, random search, directional movement and arrestment closer to and at the site source. Patterns of tick migratory paths to their respective feeding sites were characterized and quantified in both species. These were made up of runs with intermittent stops, all producing curvilinear tracks. The results of locomotory activities demonstrated a high promotion of completion of paths to the preferred feeding sites, along with high success rates of feeding site location (67.5-90.0% for R. appendiculatus; 69.8-85.6% for R. evertsi). The results also showed variations in mean walking speed between sexes, species and release points on the host. Mean velocity for males and females averaged 0.09 and 0.41cm/min in R. appendiculatus and 0.24 and 0.58cm/min in R. evertsi. Assays of tarsi painting on R. appendiculatus and R. evertsi showed that these were capable of discriminating their respective feeding sites using olfactory cues. In both species, tarsi-coated individuals were less able to orient toward or locate efficiently the relevant anal or ear sites (P<0.001). In situ and laboratory assays have implicated primarily site-borne stimuli as mediating factors in this orientation. This kairomone-driven mediation appears to be enhanced by intraspecific signals emitted by feeding ticks present at the feeding site, since ear sites loaded with live ticks (P<0.01) or rinses of fed ticks (P<0.01) were more attractive, although not significantly, compared to control tick-free ears. Specific behaviours leading to the location and finding of the feeding sites namely: arousal, activation, arrestment and aggregation in response to olfactory stimuli were examined. Arousal tests (in a Y-olfactometer) on R. evertsi and R. appendiculatus exposed to odour extracts from ear and anus resulted in scanning and residence response patterns that correlated with the stimulatory or inhibitory nature of each extract. Release of ticks in situ resulted in the activation of the tick by the host odours after a short latent period which decreased with decrease in distance from the feeding site. Likewise, walking speed of both species resulted in gradual decrease and eventual arrestment in the proximity to the feeding site. Tick velocity correlated with distance and arrestment was more evident at close range (25 cm away from any site). On the other hand, artificial substrates impregnated with feeding site materials (anal or ear extracts) caused walking arrestment of the relevant species (P<0.01) and evoked in the tick characteristic klinokinetic path patterns on the odourized arena. Significant aggregation responses of male and female ticks of R. appendiculatus occured on calved scrotum smeared with hexane rinses obtained from fed male and female ticks (P<0.05). The aggregation responses increased slightly with increasing concentrations of the rinses. The aggregation factor remains to be characterized. Olfactometric assays showed that extracts in washings from various body parts, namely belly/axillae, neck/dewlap and leg were less or unattractive to the adults of R. appendiculatus. On the other hand, ear and anal extracts elicited strong attraction to the adults of R. appendiculatus (P<0.001) and R. evertsi (P<0.001), respectively, in a dose-dependent fashion. Nymphs and larvae of R. appendiculatus, in contrast, were significantly repelled (P<0.01). Trapped volatiles from the host were significantly attractive to the ticks than the washes (P<0.001), but the blend of the two was m ore attractive compared to the individual extracts. The additive effect of the two suggests a dual kairomonal set of components comprising short-range/contact signals and volatile components which mediate feeding selection in this tick. Cross-assays involving the use of extracts from a site preferred by one tick species showed strong repulsive effect on the other species. Thus, a 'push-pull' mechanism has been proposed to explain highly successful tick orientation and feeding site finding on host and the difference in this regard in these two tick species. The 'pull' component is made of interspecific signals from the preferred sites augmented by intraspecific signals from successfully feeding ticks. The 'push' component comprised of repellents from unpreferred site, which ensures that the tick does not mistakenly orient in that direction. Repellent extracts from unpreferred feeding host sites and the essential oil of Ocimum suave (a tick repellent shrub) were used to study possible disorientation of R. appendiculatus and .R.. evertsi toward their respective feeding sites. Cattle repellent extracts and the essential oil of O. suave applied as smears to serve as barriers across tick migratory paths to the feeding sites, were disruptive at all concentrations tested. The host extract (P<0.05) as well as the plant extract (P<0.001) significantly reduced the success of R. appendiculatus and R. evertsi to reach their target site. Ear and anal extracts were found to have short-lived persistent effect on the target ticks, unlike the essential oil of O. suave, which was effective for several days during the test period. This may be attributed to differences in concentration rather than intrinsic activity. These results suggest possibilities of manipulating the host and feeding site location behavior of ticks on-and- and off-host using appropriate semiochemicals as tactics in the management of tick populations.
Biodiversity of wild silkmoths (lepidoptera) and their potential for silk production in East Africa
(2012-04-11) Kioko, Esther N.
Wild silk production is a unique eco-friendly agro-practice with the potential for environmental amelioration, employment and income generation. The present utilisation of wild silkmoths hardly accounts for 5% of the rich potential and most of the production is from the Far East countries. The steadily growing demand for silk in all consuming countries provides excellent opportunities for any country to venture into wild silk production. In East Africa, wild silk production would be ideal for generation of supplementary income to resource-poor farmers, reducing the destruction of their host plants, promoting conservation of the silkmoths and at the same time permitting positives utilisation of these biology resources by the local community. In Kenya, Uganda and Tanzania, 58 wild silkmoth species of three lepidoptera families, Saturniidae,Lasiocampidae and Thaumetopoeidae were recorded. These species diversity varied in these three families. In family Saturniidae, 19 species were recorded in 6 genera, 33 species in 17 genera in the family Lasiocampidae and 6 species in one genus in family Thaumetopoeidae. Two case studies carried out on the distribution of Bridelia micrantha (Hochst) Bail (Euphorbiaceae) the hostplant of the wild silkmoth Anaphe panda (Boisduval) (Thaumetopoeidae) and Sclerocarya birrea, (A. Rich.) Hochst. (Anacardiaceae) the host plant of the silkmoth Argema minosae (Boisduval)(Saturniidae) revealed that the hostplants are widely distributed in the three East African countries. In western Kenya, a ground survey confirmed the availability of B. micrantha with 84% of the farmers having it in varying numbers in their land. A questionnaire distributed to 50 local farmers near the Kakamega forest responded positively (98%) to the potential of initiating wild silk farming as an extra source of income. Further phenological studies on selected species, Gonometa sp. (Lasiocampidae) at Nguni, Mwingi and A. mimosae at Sultan Hamud, Makueni, Kenya showed that these silkmoths have two generations each year. The adult moth emergence synchronised with the hostplant state, which was also influenced by weather conditions. A high larval mortality of the silkworms of both species was observed in the field. The overall mortality from the first instar to the onset of cocoon spinning for Gonometa sp. reared on caged Acacia elatior Brenan was 82.9% during the short rains of 1996 and 78.9% during the short rains of 1997. In A. mimosae, reared on the hostplant Sclerocarya birrea, 80.6% larval mortality was recorded during the short rains of 1997. Rearing the Gonometa sp. silkworms in net sleeves tied to the hostplant branches reduced the mortality to 23.9% In both species, the pupal stage was the longest indicating the possibility of pupal diapause. Gonometa sp. pupae observed in controlled environmental conditions in an incubator had a significantly shorter life span (87.2 + 3.6 days) compared to those observed under room condition (124.0 + 11.2 days). This is an indication that the pupal diapause in these species can be manipulated for continuous cycle of the silkmoth generations depending on the foodplant state. Predators attacking Gonometa sp. and A. mimosae in the field belonged to three insect ordes, Hemiptera, Orthoptera and hymenoptera. Formicid ants were abundant. Pentatomid bugs of the sub-family Asopinae, Maccroraphis spurcata Walker were observed in Sultan Hamud sucking fluids and killing larvae of A. mimosae. Field collected eggs and cocoons of Gonometa sp. and A. mimosae yielded hymenopteran and dipteran parasitoids. Mesocomys pulchriceps Cameron and Pediobius anastati (Crawford) were identified from the eggs of both silkmoth species. Telenomus sp. and an unidentified Encyrtidae were recorded from Am mimosae eggs. No parasitoids were obtained from A. mimosae cocoons. From Gonometa sp. cocoons, unidentified Tachinidae together with hymenopterans Goryphus sp., Eurytoma sp and unidentified Chalcidoidea were recorded. These parasitoids from the cocoons spoilt the continuity of the silk fiber by making exit holes for the adults to emerge. Cocoons of A. mimosae were not reelable but those of Gonometa sp. gave long filaments of lustrous brown silk. Females gave longer silk thread (706.34 + 222.4 m) compared to males (521.49 + 204.2 m). The mean weight of silk from females was 0.43 + 0.2 g and 0.21 + 0.10 g from males. 2,326 to 4,762 cocoons are required to make one kilogram of Gonometa sp. silk.
Bioecology of the new invasive fruit fly Bactrocera invadens (Diptera:Tephritidae) in Kenya and its interaction with indigenous mango-infesting fruit fly species
(2011-07-11) Ivan, Rwomushana
Bactrocera invadens Drew, Tsuruta & White (Diptera: Tephritidae), an alien invasive fruit fly species of Asian origin was first detected in Kenya in 2003. This pest has rapidly spread across sub-Saharan Africa and is currently reported from at least 24 countries. Because of its novelty status, there was no information on its biology and ecology that could aid development of management efforts. There was also evidence that B. invadens co-infested the same fruits with native fruit fly species and it was speculated that this could result in competitive displacement of native fruit flies. This study, therefore, was initiated to establish the bioecology of B. invadens in Kenya and its interaction with indigenous mango-infesting fruit fly species. The first step was to identify the most suitable temperature range for development and survival of immature stages of this pest. Studies were conducted in the laboratory at four constant temperatures of 15, 20, 25, 30 and 35°C. The longest development period occurred at 15°C (75.74 days) and was shortest at 30°C (17.76 days). The optimal temperature for survival was found to be 25°C while 35°C was the most lethal temperature. Countrywide surveys were then initiated to establish the host plants of this pest. The survey revealed that B. invadens infested fourteen plant species particularly Mangifera indica L., Musa sp. AAA and citrus [C. limon (L.) Burm. f., C. sinesis (L.) Osbeck and C. reticulata Blanco.] and the wild plants Sclerocarya birrea (A. Rich) Hochst. and Terminalia catappa L. In laboratory host preference studies, M. indica and Musa sp. were found to be the most preferred host plants among the nine cultivated plant species tested. The spatial and temporal population dynamics of this pest was also studied and revealed that three fruit fly species infested mango namely B. invadens, Ceratifs capitata (Wiedemann) and Ceraftis cosyra (Walker). The relative abundance index (RAI) of these pests in infested fruit was in the order B. invadens > C. cosyra > C capitata which was similar to the indices of adult population obtained by trapping. Percent fruit fly infestation and B. invadens fruit fly density was found to be always higher in mango on the ground than on the trees, demonstrating that mango fruits that fall to the ground serve as a major breeding site and may be a reservoir of non-immigrant B. invadens population in mango orchards in Kenya. The efficacy of the Easy, Multilure and Lynfield traps all baited with Nulure, Torula Yeast, Corn steepwater and a locally produced yeast product for trapping B. invadens was also evaluated. The multilure trap baited with torula yeast or nulure was the most attractive trap-bait combination and captured 19.7-30.3 B. invadensltrap/day and 10.54 -22.97 flies/trap/day respectively. In interspecific competition studies, there were significant differences in the larval developmental time, weight of puparia and number of adults that emerged of B. invadens, C. capitata and C. cosyra when the insects were soquentially co-infested on rearing medium at constant temperatures. When B. invadens was introduced into whole fruit before C. cosyra, the number of emergent adults of the IMa was greatly suppressed. Higher number of C. capitata adults was, however, recovered when in cross infestation with B. invadens particularly in the treatments where G capftata had a two or three days head start. This study demonstrated that the oedumisms contributing to the displacement of C. cosyra by B. invadens may be erodated with intricate interactions between resource pre-emption and fluctuations in temperature in mango agroecosystems
Breeding of the honey bee (apis mellifera l.) and its potential for royal jelly production in Kenya
(Kenyatta University, 2004-07) Maundu, Elliud M.; Mueke, Jone M.; Raina, Suresh K.
Royal jelly is a creamy, milky white, strongly acidic and highly nitrogenous substance secreted by the hypopharyngeal and mandibular glands of worker honey bees at the ages of 5 - 15 days of age. The jelly is fed to queens through out their life and also to drone and worker larvae of less than 3 days old. The principal constituents of royal jelly are water, protein, lipids, sugars and mineral salts. Due to differences in climate, Apis mellifera races have evolved in response to the local environmental conditions, with each race acquiring a different potential for production of honey and other hive products / and even pollination of crops. In Kenya, new generation commercial hive products like royal jelly, propolis and pollen are insignificantly produced or utilized due to lack of knowledge on production skills, awareness and undeveloped marketing systems and also due to the nature of hives used. The aim of this study was to develop a royal jelly production system and breed for high honey production and reduced defensiveness using the East African honey bees. Royal jelly production was done in queenright colonies following the procedure of Laidlaw and Eckert, (1962). Defensive behavior was evaluated following the procedure of Stort (1974) and Collins et al., (1984). The bred queens were mated by instrumental insemination and their honey production and defensive behavior compared to that of colonies headed by non-selected queens. There were no significant differences between Apis mellifera scutellata and Apis mellifera monticola in the cell reception rates and mean royal jelly yields. Grafting larvae at the age of 24 hours significantly increased queen cell reception and royal jelly yields compared to those of larvae grafted at the ages of 36; 48 and 60 hours. Supplementary feeding significantly increased colony cell reception, mean royal jelly yields per queen cell and colony royal jelly yields. Harvesting royal jelly 2 days after grafting resulted into a higher number of harvested cells compared to harvesting in a 3- day cycle. However, cells harvested 3 days after grafting yielded more royal jelly per queen cup compared to that produced by cells harvested 2 days after grafting. However, royal jelly yields were not significantly different in the 2 and 3-day cycle. The major components in the Kenyan royal jelly were found to be moisture, lipids, proteins, sugars and ash and their composition was comparable to that reported in literature. Colonies of Apis mellifera scutellata were found to have variations in both defensive behaviour and honey production. A negative and significant correlation for SN and Tl S was recorded. Variations were noted in honey production with annual honey yields of 27 - 48 kilograms per colony. There were no significant differences in sting number (SN), time to first sting (Tl S) and honey production between colonies headed by selected queens and those headed by unselected queens. Colonies headed by selected queens had significantly higher queen cup acceptance rates and royal jelly yields compared to those headed by unselected queens.
Cancer Epidemiology, Transforming Growth Factor-Beta Levels and Associated Infections in Meru and Tharaka Nithi Counties, Kenya
(Kenyatta University, 2022) Muthoni, Gitonga Ciriaka; Michael Gicheru; Joshua Mutiso
Cancer is one of the leading causes of morbidity and mortality worldwide with approximately 14 million cases annually. In Kenya, cancer as a disease ranks third as a cause of death after infectious and cardiovascular diseases. In Meru County, cancer cases have reached alarming levels. Out of all cases referred to Kenyatta National Hospital in Nairobi for cancer therapy in 2016, fifteen percent were from Meru County. Factors contributing to high cancer incidences in Meru County are not well documented. In addition, the true prevalence of cancer in this County is not known, therefore, much emphasizes of putting proper infrastructural facilities and human capacity development is not in place to combat cancer. The current study was aimed at determining the prevalence, distribution, risk factors and infections associated with cancer in Meru and Tharaka Nithi Counties. The study also aimed at determining the levels of transforming growth factor-beta levels in breast cancer patients with an aim of exploring application of these data in breast cancer diagnosis and management. A random selection of patients aged between 5 to 82 years clinically diagnosed as cancer patients who were visiting Meru and Chuka General Hospitals for a period of one year were recruited for the study. A total of 196 cancer patients were recruited for the study. The participants were requested to give a verbal consent and respond to a brief questionnaire concerning their age, type of cancer they were suffering from, exposure to predisposing factors, chronic coinfection, family history of cancer among other factors. Blood samples were collected to test for immunosuppressive cytokine and infectious diseases. Stool samples were collected and analysed by microscopy to detect for gastrointestinal parasitic infestation. Data was analyzed using statistical package for social sciences (SPSS). Statistical analysis involved descriptive statistics such as frequencies, standard deviations and means of various risk factors. Analysis of variance (ANOVA) was used to analyse the differences among means of transforming growth factor-beta levels at different cancer stages. Chi square was used to compare categorical data. A P value ≤ 0.05 was considered statistically significant. The current study established that the prevalence of cancer in people visiting hospitals in Meru and Tharaka Nithi Counties was 32% and 38% respectively. Further, the study found that the prevalence trends of cancer cases in the two counties have been increasing over the last eight years (2011-2018). People above 50 years of age are the most prone to cancer followed by people in the age bracket of between 31 and 50 years. The risk factors for cancer included age, diet, unregulated use of agrochemicals, tobacco use, use of Khat, public water supply, environmental pollutants like smoke and contraceptive use. Elevated levels of transforming growth factor-beta were found in breast cancer patients when compared with healthy individuals. The most common diseases in cancer patients before cancer diagnosis included HIV/AIDS, pneumonia, tuberculosis, Human papillomavirus, diabetes, H. pylori infection and malaria. The study concludes that cancer is prevalent in Meru and Tharaka Nithi counties and the increases are associated with exposure to risk factors. It is therefore recommended that proper infrastructural and human capacity development be put in place to combat cancer. It is recommended that transforming growth factor-beta be evaluated further for its potential application in cancer diagnosis and staging.
Cellular immune responses in susceptible and resistant schistosomiasis patients co-infected with HIV-1 in Kisumu District, Kenya
(2012-01-05) Pauline, Ngina Mutie
This study aimed at dissecting immune mechanisms of resistance/susceptibility in schistosomiasis in a well-characterized cohort of hyper exposed adults with a high prevalence of HIV-1. The impact schistosome infections may have on the HIV/AIDS pandemic was investigated. First the general effect of HIV-1 co-infection on immune responses to schistosomes was examined. Schistosomiasis patients with HIV-1 co-infections had significantly lower interleukin (IL) -4 (P = 0.03) and IL-10 (P =0.005) production than did HIV-1 negative individuals. In contrast, gamma interferon (IFN-) production levels were similar between the two groups. Furthermore, in patients with HIV-1, a decrease in CD4+ T cells was correlated with an increased Th1/Th2 cytokine production ratio (r = -0.53; P = 0.01). The differences in the immune response profile of persons without liver fibrosis compared with persons that have schistosomiasis related pathology as detected by utrasound, and how this may be affected by a patient's HIV-1 status was also investigated. The proportion of patients with fibrosis was lower in HIV-1 seropositive (4%) than in HIV-1 seronegative groups (20%) even though this was insignificant by Fisher's exact test (P = 0.1014, odds ratio = 3.067). Mean CD4+ cell count levels were significantly lower (P > 0.01) in the IP > A (pathology) group than in the IPA (normal liver) group after controlling for HIV-1 status but CD8+ cell counts were similar in patients with or without fibrosis. Generally, all cytokine production by PBMC in response to phaetohaemaglutinin PHA, SEA (egg antigens) and SWAP (adult worm antigens) was higher in the IPA group in both the HIV-1 positive and negative patients than in the IP > A. However, following chemotherapeutic treatment of the hepatosplenic patients, responsiveness to both schistosome-derived antigens was elevated, with the SWAP driven responses being more dramatically increased. These immune response profiles were compared with susceptibility/resistance to schistosomiasis. IL-4 and IL-5 production were strongly correlated with susceptibility (P = 0.0010, and P = 0.0005 respectively) while there was no relationship susceptibility and IL-10 and IFN- production. As a follow up of these immune response studies in schistosomiasis, their possible effect of on HIV-1 susceptibility was investigated. The in vitro susceptibility of CD4+ T cells and monocytes from persons with schistosomiasis compared to cells from former patients and cells obtained from persons with no prior exposure to schistosomes was investigated using in vitro HIV-1 infection assays. Viral replication dynamics were monitored in the cell culture supernatants using a P24 (HIV core antigen protein) ELISA for determination of viral load. P24 mean levels were higher for cells from active infection patients. However, stimulated cells generally produced more virus than unstimulated cells and stimulated cells from former patients were more susceptible than antigen stimulated cells from active infection patients (P < 0.1; Mann Whitney U). Levels of the chemokine HIV co-receptors CXCR-4 and CCR-5 as analyzed using FACS, were significantly higher on cells obtained from egg positive patients than on cells from egg negative patients (P < 0.03; t-test). Thus schistosomiasis and HIV-1 have deleterious effects on the host, both singly and co-infectionally. These findings suggest that parasitic diseases like schistosomiasis may be an important component in the natural history of HIV/AIDS and that control of parasitic diseases may have additional benefits with respect to the HIV/AIDS epidemic in Sub-Saharan Africa. Thus the control of parasitic diseases should be integrated in HIV/AIDS control strategies.
Characterisation of placental malaria in olive baboons (pappio anubis) infected with plasmodium knowlesi H strain
(2011-07-11) Mustafa, Barasa; Gicheru, M. M.; Hastings Ozwara
Pregnant women have increased susceptibility to malaria infection. In these women, malaria parasites are frequently found sequestered in the placental intervillous spaces, a condition referred to as placental malaria (PM). Placental malaria threatens the health of the mother and the child's life by causing intrauterine growth retardation, abortions, still births and reduction in gestational age. An estimated 24 million pregnant women in SubSaharan Africa are at risk. Mechanisms responsible for increased susceptibility in pregnant women are not fully understood. Baboons are susceptible to Plasmodium knowlesi and have similar host pathogen interactions and reproductive physiology similar to humans, making them attractive for the development as a model for studying mechanisms underlying development of placental malaria. This study exploited the susceptibility of baboons to Plasmodium knowlesi infection to develop a non-human primate (baboon) model for studying PM. The main objective of the study was to demonstrate PM and characterize immunological mechanisms underlying the pathogenesis of PM in baboons infected with Plasmodium knowlesi. The pregnancies of three time mated adult female baboons and their gestational levels (one in its second trimester and two in their third trimester) were confirmed by ultrasonography. On the 150th day of gestation, the pregnant baboons were infected with Plasmodium knowlesi H strain parasites together with four non pregnant controls. Peripheral parasitaemia development was monitored on a daily basis from two days post inoculation. Collection of sera, plasma, mononuclear cells and haematological samples was done on a weekly basis. Peripheral blood mononuclear cells (PBMC) were stimulated in culture with concanavalin A and P. knowlesi antigens and their proliferation quantified. Sera cytokine and immunoglobulin concentrations were measured by ELISA using respective enzyme conjugated antibodies. Two pregnant baboons aborted (one on day 6 and the other on day 7 post infection) and cesarean section was only done on one baboon. Smears prepared from placental blood demonstrated the presence Plasmodium knowlesi parasites in all the sampled placentas. On average, the pregnant baboons had more than 29 fold higher placental parasitaemia than simultaneous peripheral parasitaemia. This shows that Plasmodium knowlesi preferentially sequesters in the baboon placenta just like Plasmodium falciparum does in humans. Two baboons that had high placental parasitaemia experienced abortion, which is a sequele of human placental malaria. Results indicate that PM in this model is associated with significant (P < 0.05) suppression of immunoglobulin G, Interferon gamma, and interleukin 6 responses. Tumour necrosis factor alpha responses were significantly upregulated (P < 0.05) while immunoglobulin M, interleukin 10, interleukin 12, interleukin 4 and PBMC proliferation responses did not differ from controls (P > 0.05). These data are consistent with some findings from human studies, showing the feasibility of this model for studying mechanisms underlying placental malaria. The study has contributed valuable data to be used in further studies and the development of preventative, control and therapeutic measures against PM in women
Characterization and Control of Pathogenic Parasites in Nile Tilapia (Oreochromis Niloticus Linnaeus 1758) in Fish-farming Systems in Bungoma County, Kenya
(Kenyatta University, 2020) Makilla, Davies Mukwabi
In Kenya, fish farming has been expanding in recent years, with Government support through financial and input subsidies to small scale farmers. The sub sector generates a variety of benefits such as food and nutrition and develops trade. However, the sub sector faces the challenges of fish diseases, given that the fish production facilities support high-density living conditions that are favorable for spread of parasitic diseases. Besides, when fish that is infected is consumed by humans, the humans may be infected, especially when eaten fresh. Infected fish lowers their market value and sunctions may also be imposed on fish exports. Knowledge of fish parasites in aquaculture systems as well as treatment options available would enlighten fish farmers on the specific actions to take in order to harvest quality fish. The study was cross sectional carried out in Bungoma County from August 2015 to Decemebr 2017. The main objective of the study was to characterize and evaluate control options of pathogenic parasites present in fish farming systems in Bungoma County. Bungoma County was chosen for this study because it is one of the Counties that has high potential for fish farming. The County hosts one out of the public fish farms and hatcheries at Chwele besides authenticated private fish hatcheries. He hatcheries are sources of fish fingerlings as well as training and demonstration centres for fish farmers. At every fish pond, six water quality parameters were assessed using a portable auto sampler. Farmed Nile tilapia was randomly sampled to determine the pathogenic parasites and bacteria present in various organs. Commercial fish feeds were also purchased from two fish feed millers in Bungoma County and assessed for parasite presence. Polymerase Chain Reaction (PCR) and genetic sequencing analysis were conducted in order to assess the genes responsible for antimicrobial resistance. The data was entered into Micro Soft Excel (Windows 10) spreadsheet and analysed by SPSS Software. It was found that there was significant difference only in temperature of the pond water sampled across the sub counties (F=15.5; df=5; p<0.001). Helminthes recovered were Pallisentis tetraodontis, Pallisentis spp., Acanthocephalus spp., Procamallanus spp. and Philometroides spp. from Nile tilapia and Cleidodiscus spp. from pond water. Bacteria that were isolated from Nile tilapia were Vibrio vulnificus, Vibrio parahaemolyticus, Aeromonas hydrophila, and Pseudomonas aeruginosa. In fish pond water, Aeromonas hydrophila was isolated while Streptococcus iniae was isolated from fish feeds. Besides, there was a significant difference in distribution of total viable aerobic colony counts in fish ponds water across the different sub counties (H=6;df 5; P< 0.041). Furthermore, it was found that there was significant difference in the distribution of Aeromonas hydrophila in fish ponds across the different sub counties (H=3;df;P< 0.016). The external parasites were eliminated by formalin (36% formaldehyde) at concentration of 25ppm for 1h and Hydrogen peroxide at 75ppm for 30 min. The bacterial isolates were found to be significantly different in responses to antimicrobial agents (OLR;df= 16; P<0.00). When the bacterial isolates were subjected to PCR, all five bacterial pathogens isolated from fish, pond water and fish feeds were found to contain blaTEM gene amplified at 424bp. The sequences blaTEM gene returned 100% identity with GenBank Accession number; BankIt2236899 Seq1a MN114035 to Seq 9b MN114052). This study found that the blaTEM gene was present in recovered Vibrio parahaemolyticus, Aeromonas hydrophila, Pseudomonas aeruginosa and Streptococcus iniae. It is recommended that Formalin and hydrogen peroxide as well as potassium permanganate should used to manage fish helminthes in the ponds
Characterization of cytotoxic tlymphocyte responses to pre-erythrocytic stage candidate vaccine antigens in Kenyans naturally exposed to plasmodium falciparum malaria
(2012-02-13) Ong'echa, John Michael
One of the major limitations in the control of malaria either through vaccine development of use of insecticide-treated bed nets (ITBN) has been the lack of in vitro protection correlates and understanding of what constitutes immunity to malaria. Furthermore, ITBN intervention, as well as the infection with human immunodeficiency virus (HIV) prevalent in most malaria endemic areas, may interfere with the development of protective immunity. This study was designed to answer some of these questions. IFN- was characterized and lymphoproliferative responses to previously defined CD8+CTL epitopes from 6 pre-erythrocytic stage antigens in 107 children aged 6 months to 2 years from a community based birth cohort in western Kenya were determined. The antigens studied included liver stage antigen (LSA) - 1, LSA-3, thrombospondin related adhesive protein (TRAP), exported protein-1 (EXP-1), circumsporozoite protein (CSP) and Pfs16. The results of this study showed that IFN--positive responders, suggesting that IFN- immune responses to these pre-erythrocytic antigens were associated with improved haemoglobin levels (P=0.002). Children who responded by lymphoproliferation had a significantly longer time to first documented malaria parasitaemia after birth (P=0.007). To assess the effect of ITBN intervention on the immune responses of children less than 5 years old living in a malaria endemic area of western Kenya, 216 children (106 children using ITBN and 110 not using ITBN (controls) were involved in this study. IFN- and lymphoproliferative responses to the 6 pre-erythrocytic stage antigens were assessed in a similar way as the first part of this study. There was no relationship between these responses, haemoglobin levels and bed net use. The prevalence and density of P. falciparum infection at the time of sample collection was significantly lower in the ITBN users compared to the controls (P=0.027 and P=0.044, respectively). In determining the nature of the naturally acquired immunity to malaria, immune parameters including HLA-DR, Fas, and cytokine production were compared between immune adults and non-immune children, HIV-infected and non-infected adults; and HIV-infected and non-infected children, to determine the effect of HIV infection on the expression of the immune markers on the memory T cells. It was observed that the un-infected adults had high frequencies of activated memory T cells compared to the un-infected children. Similarly, these un-infected adults had high frequencies of B cells expressing costimulatory molecules CD80, memory T cells expressing CD28 and CD154, memory TG cells and CD3+T cells expressing Fas compared to the children. The cytokine pattern in the adults was a dominant IFN-/IL-2 type. HIV infection in the adults induced significantly high activation of the CD3+ and memory T cells compared to the un-infected adults. It also induced significant expression of Fas and CD152 on memory T cells, and CD86 and CD 80 on B cells compared to the un-infected adults. The cytokine profile was IFN- with impaired IL-2. In children the effect of HIV infection was greatest, resulting in increased activation and memory T cells, increased expression of CD80 and CD86 on B cells, and Fas expression. Cytokine profile was an enhanced IFN-/IL-2/IL-4 type. These results suggest that the immune adults have a different immune constitution compared with the malaria non-immune children. These patterns are affected by HIV infection, more so in the children. It is therefore critical that the role of these molecules in malaria-specific immunity be determined for the rational development of malaria vaccines.
Circulatory Cytokines and Hematological Profiles as Biomarkers of HIV and AIDS Progression
(Kenyatta University, 2019) Mugwe, Jane Nyambura
Cytokines are polypeptides that have a fundamental role in communication within the immune system and in allowing the immune system and host tissue cells to exchange information. They play a central role in the pathogenesis of many diseases including Acquired Immunodeficiency Deficiency Syndrome (AIDS). Cytokines reflect the local or systemic inflammatory milieu, and could serve as predictive biomarkers in Human Immunodeficiency Virus (HIV) infection. Hematological abnormalities are among the most common complications caused by HIV infection and seem to be dependent on the level of virus replication. The aim of this study was to identify circulatory cytokine biomarkers and hematological profiles measureable in blood that could predict the progression of HIV disease in the course of infection. This study was done at the Nakuru Provincial General Hospital (PGH). Eighty individuals were recruited for this study that comprised of forty individuals newly diagnosed with HIV-1 (treatment naïve), twenty HIV negative individuals and twenty HIV positive individuals that were on treatment with highly active antiretroviral therapy (HAART). Hematological parameters were analyzed using hematology auto analyzer system; cytokine types and concentrations were determined by flowcytometry using multiplex cytokine immunoassay and CD4 T cell counts were measured by flowcytometry using Becton and Dickinson Fluorescence Activated Cell Sorter (BD FACS) count. Statistical analysis were done using SPSS version 17. Descriptive statistics were applied; analyses of variance was used to determine the differences in mean circulatory cytokine levels, mean hematological profiles and mean CD4 T cell counts between the subgroups forming the study population. The associations between immunological and hematological profiles were determined. The study found significant differences in the mean Interleukin12p70 (p<0.001), Tumor Necrosis Factor (p<0.05), Interleukin 10 (p<0.05), Interleukin 6 (p<0.005) and Interleukin 1-β (p<0.05) between treatment naïve HIV patients, HIV patients on HAART and HIV negative patients. No significant differences were found between the mean White Blood Cell counts and Red Blood Cell counts (p>0.05) between the treatment naïve HIV patients, HIV negative patients and HIV patients on HAART but there were significant differences between the mean hematocrit (HCT) (p<0.05); hemoglobin (HGB) (p<0.05) and platelets (PLT) (p<0.05). This study also found significant differences in the mean volume of erythrocytes (MCV) (p<0.05), mean content of hemoglobin (MCH) (p<0.05), mean concentration of hemoglobin (MCHC) (p<0.05), mean platelet volume (MPV) (p<0.001), relative width of the distribution of platelets (PDW) (p<0.001) and the absolute content of the mixture of monocytes, basophils and eosinophils (Mid#) (p<0.05). Significant differences in the mean CD4 T cell counts (p<0.001) were observed between the treatments naïve HIV patients, HIV negative patients and HIV patients on HAART. The study found several identical associations between immunological and hematological profiles among the study groups. The study showed that early period of HIV infection is characterized by varying circulatory cytokine levels and could be useful biomarkers and indicators of early immune activation of HIV disease. The results from this study also show that acute HIV infection affects hematological profiles, involving all the blood parameters, some of which may act as indicators of HIV disease progression. The study recommends the use of low cost hematologic tests as biomarkers of disease progression in resource limited settings and also a holistic treatment of HIV infected patients that include supplements to monitor and improve blood parameters and indices in addition to antiretroviral therapy.
Comparative evaluation of certain aspects of the biology of cotesia flavipes and cotesia sesamiae (hymenoptera: braconidae) for the management of chilo partellus (lepidoptera:pyralidae) in Kenya
(2012-04-11) Sallam, Mohamed Nader Said
A comparative study was conducted on two gregarious larval endoparasitoids of lepidopteran stemborers, Cotesia flavipes Cameron and Cotesia sesamiae (Cameron) (Hymenoptea: Braconidae). The first parasitoid was imported from Pakistan and released at the Kenya Coast during the long rains of 1993 in an attempt to increase the natural control of the spotted stemborer, Chilo partellus (Swinhoe) (Lepidoptera: Pyralidae). The second is indigenous to Africa, and it is the most common parasitoid of gramineous stemborers in Kenya and other parts of East and Southern Africa. The dispersal capacity of the exotic parasitoid was tested in a 100x100 meter maize field at Kilifi, Kenya coast. Results showed that female parasitoids were able to fly at least 64.03 meters downwind before parasitising a host. The highest rate of parasitism was found inside the maize plant where the majority of suitable hosts were located. A study of the funcional response of the two parasitoids on C. partellus and an indigenous stemborer, Sesamia calamistis (Lepidoptera: Noctuidae), was conducted in large field cages at the Kenya coast and in the laboratory. Results showed that C. Flavipes had as stronger functional response than C. Sesamiae when C. Partellus was the host, while differences were not significant when S. Calamistis was the host. Studies on host discrimination indicated that naive as well as experienced females of the two parasitoids oviposited in hosts previously parasitised by the other species. However, experienced female of the two species were significantly more attracted to non-parasitised host larvae than larvae parasitised by conspecific females. Fitness consequences of superparasitism were examined for the two parasitoids on both hosts. Progeny production of C. flavipes increased gradually with increasing numbers of stings, but leveled off at three stings per C. partellus larva,then decreased. Cocoon weight, emergence and sex ratio of progeny were not affected by superparasitism. However, larval development was lengthened, and the longevity and fertility of adult progeny decreased. When S. calamistis was the host, no difference was found in the duration of immature stages, emergence rate, progeny production or sex ratio of the progeny, but cocoon weight, adult longevity and fertility were negatively affected. When C. partellus was the host for C. sesamiae, low progeny production and poor survival of host larvae were recorded over the different number of stings. Moreover, larvae that were stung more than three times died. Multiple stinging led to a male biased sex ratio and low fertility of female progeny. When S. calamistis was the host, progeny production of C.sesamiae increased with the number of stings, but leveled off at at three stings per S. Calamistis larva, then decreased. No significant effect of superparasitism was found on the rate of emergence, longevity or sex ration of adult progeny. However, longer duration of immature stages, lower cocoon weight and lower fertility of adult females were recorded. Multiple parasitism studies showed that C.flavipes was able to eliminate C. sesamiae during the egg stage when C. partellus was the host. However, When S. calamistis was the host, both Cotesia species emerged from host larvae, but with a higher number of C.flavipes. C. flavipes appeared to be competitively superior, both intrinsically and extrinsically, to its African Congener, C.sesamiae, when C. partellus was the host. Both species were equally competitive when the host was S. calamistis. A possibility of local displacement of C.sesamiae by C. flavipes in areas dominated by C. partellus is therefore expected. The implication of this displacement on the impact of biological control of stemborers in Kenya is discussed.
Comparative studies on the adult dispersal behaviour of busseola fusca (fuller) (Lepidoptera:Noctuidae) and chilo partellus swinhoe (lepidoptera:pyralidae)
(2012-04-04) Mbugi, J.P.
Two oil soluble dyes, Calco Red N-1700 and Sudan Blau-670 were added to the artificial diet of Chilo partellus and Busseola fusca. The two dyes effectively marked the larvae, adults, eggs and first stage F1 larvae. The dye treatments did not have any effects on mean fecundity, longevity, pupal weights and flight duration of mated female moths of the two stem borer species. Further experiments showed that, B fusca reared on a normal diet for 18 days and transferred to the Calco Red dyed could still lay marked eggs. The dye was found to be more appropriate for further marking experiments because marked moths laid red eggs which can easily be detected on maize plants during dispersal studies. Busseola fusca C.partellus reared on different host plants showed moths laid red eggs, which can easily be detected on maize plants during dispersal studies. Busseola fusca and C. partellus reared on different host plants showed better growth and development on cultivated sorghum, maize and the wild sorghum species (Sorghum versicolor and S. arundinaceum) while the poorest performance was on napier grass (Pennisetum purpureum). The poor performance observed on P. purpureum may be attributed to presence of antibiotic factors or to poor nutrients contents. The two wild sorghum species may therefore act as important alternate hosts or trap crops. Two-choice oviposition preference experiments where insects reared on a given host (''rearing host'') were tested for oviposition alternately with each of the other hosts (''test host'') revealed that for both species, moths which were reared on a given host preferred to lay more eggs on that host. For example, B. fusca reared on cultivated sorghum and tested for oviposition alternately with either maize or Napier glass preferred to lay more eggs on sorghum. Similary C. partellus reared on maize and tested for oviposition alternately with cultivated sorghum and wild sorghum (S.versicolor) preferred to lay more eggs on maize. These findings reveal that there can be a variation in an insect's oviposition response to a plant as a result of its previous larval food experience. This altered oviposition preference in favour of the plant species upon which the larvae were reared on is a phenomenon referred to as Hopkins' host selection principle (Hopkins, 1917). However, this principle was not evident in multiple choice oviposition preference experiments indicating that its validity as a general principle operating in adult oviposition preferences of B. fusca and C. partellus moths still remains to be proved. Results of the experiment investigating changes in insect density from a central release point using oviposition by internally marked female moths as a measure of insect density showed that, for C. partellus there was a profound falling off in the mean number of eggs and egg batches with increasing distance. Hence, the maize plants which were near the release point received the highest number of eggs and egg batches than those that were far away. This phenomenon referred to as ''edge effect'' could have been brought about by a situation whereby a large proportion of C. partellus female moths preferred to disperse horizontally as opposed to a vertical dispersal which could have taken them high up and possibly even outside the sampling area. As for B. fusca, the mean egg batches and egg numbers showed no significant differences and were more or less uniformly distributed throughout the dispersal distance; hence ''edge effect'' was not evident. Results also showed that at each concentric circle, more eggs of C. partellus were recovered than those of B. fusca. The higher recovery rate for C. partellus eggs is usually associated with very low dispersal rates whereas on the other hand, the lower recovery rate for B. fusca eggs is associated with high dispersal rates. Results of the experiment involving sampling to recover eggs and larvae from the wild populations of B. fusca and C. partellus showed that, the maize plants at the edge of the experimetnal plot (bordering the wild host plants) received the highest number of C. partellus eggs and egg batches, hence ''edge effect'' was evident. In contrast, the mean number of eggs, egg batches and larvae of B. fusca showed a more or less uniform distribution and therefore ''edge effect'' was not evident. Therefore B. fusca and C. partellus behave quite differently and the former distributes its eggs more or less uniformly whereas the latter lays more eggs on the nearest host plants. An important implication of ''edge effect'' is the C. partellus can be controlled by use of trap crops or by applying insecticides only on the margins of the field where infestation is severe. Most eggs of C. partellus will be laid on the trap crop, which can be destroyed or cut as fodder. However, trap crops unless very attractive may have very little value for the protection of crops against the invasion of crops by B. fusca because the latter is capable of dispersing its eggs in a more or less uniform manner and even more widely.
The conflict between modern and traditional parenting behaviours as perceived by students in some selected secondary schools in Nairobi province: counseling implications
(2011-11-08) Wang'eri, Tabitha Waime; Woye, Augustine; Orodho, John Aluko
This study was undertaken to examine and analyze the impact of westernizing influences on the parenting behaviours of modern Kenyan parents. This analysis was conducted, not by approaching these parents directly, but by means of the Internalized-OtherInterviewing technique intended to determine the perceptions of students in some selected secondary schools in Nairobi province, on the parenting behaviours of their own parents. In this regard, the critical issue was that of ascertaining the extent to which traditional parenting practices have been eroded by the multi-faceted influences impinging on the modern Kenyan family. The major purpose of the study was to isolate the traditional parenting behaviours and values that have resisted change despite these influences and those that have succumbed to the change. The sample for the study consisted of form two students drawn from a sample of secondary schools in Nairobi province. A self-developed questionnaire, containing a variety of possible parental behaviours of modern Kenyan parents was used as instrument for data collection. The researcher herself with the assistance of two research assistants administered the questionnaires directly to the students and collected the instruments immediately afterwards. The data collected were analyzed by means of descriptive statistics that helped to generate trends and conclusions that assisted in the resolution of the key questions investigated. The results showed, among other things, that parenting behaviours of modern Kenyan parents have been severely affected by a number of westernizing influences. This is evidenced by the majority of the families that have adopted monogamous marriages and who have fewer children than the traditional African family. Modernization is also evident as the number of relatives resident among the families continues to drop. The modern Kenyan family is one that avails children with modern facilities like the radio, television, video and newspapers which the adolescents studied use avidly as opposed to the traditional past where the children were socialized through communally organized activities. The mother has appeared as the dominant parent as she is in close proximity with children of both sexes while the father seems to be distanced from both sons and daughters which itself is a modern trend. Maternal domination of the domestic scene was noted to cover many areas of the child's life as the mother is reported to be more engaged than the father in parent-child shared activities, in meeting the psychological needs of children, child discipline, decision making in the home, house-keeping and child-rearing. This can be interpreted to mean that compared to those of the older generation of Kenyan parents, as highlighted in studies by Kenyatta (1938), Ngugi (1965), Omari (1972), and Nukunya (1992), children of modern Kenyan families are parented differently from those of their own parents and grandparents. A discussion of the findings was undertaken to draw out some implications of the study and to make recommendations as well for counseling purposes to enable modern Kenyan parents to contend with the new trends indicated, emanating from the study. Hence the following recommendations were proffered: egalitarian parenting and the need for mothers to tone down their maternal gate-keeping and fathers to become more participative in attending to their modern family roles. It was also recommended that parents should endeavor to understand the benefits as well as the damaging effects of the electronic devices in the home and as such, to properly guide and monitor the children's use of these facilities. Professional implications of the study were also drawn, suggesting that counselors need to be conversant with adolescents' experiences in the homes and in that way to facilitate forums aimed at helping parents to be more effective in an ever changing world. Policy makers were urged to indicate the direction along which we must go in the future if the noted devastating effects of westernizing influences on the modern Kenyan family are not to be allowed to deal an irreversible blow on the mental health and psychological characteristics of the modern Kenyan child. Recommendations for further research along the lines were also made.
Development and application of genetic markers linked to a QTL controlling resistance to trypanosomosis on bovine chromosome 7
(2012-01-04) Kang'a, Simon
Tsetse-transmitted trypanosomosis poses severe constraints to livestock productivity in sub-Saharan Africa, affecting large areas of the continent that hold the greatest potential for agricultural development. Greater exploitation of the genetic resistance to trypanosomosis (trypananotolerance) that is displayed by some breeds of indigenous West African cattle (e.g. N'Dama) is accepted as an important sustainable component for controlling the disease. It is envisaged that within-breed and crossbreeding genetic improvement of indigenous trypanotolerant breeds would be facilitated by the mapping of the chromosomal regions (quantitative trait loci, QTL) controlling trypanotolerance, followed by marker-assisted selection, or introgression of these regions, using their closely linked genetic markers. However, this prospect has been hampered by the absence of practical reliable markers for resistance due to the scarcity of genetic markers on cattle maps. Following a genome-wide scan in an F2 cross between trypanotolerant N'Dama from The Gambia and trypanosusceptible Kenya Boran, a QTL controlling parasitaemia was mapped to a 30 cM region on bovine chromosome 7 (Bta 7). As a means of achieving higher marker density in this QTL region, and to facilitate the identification of the candidate genes mediating trypanotolerance, a combination of chromosome-microdissection, comparative, radiation hybrid (RH) and physical mapping techniques, were exploited to isolate and order new markers in the QTL region. A high-resolution 12,000 rad Bta7 RH map consisting of 55 markers was constructed in this study. The map includes: 41 coding genes, 29 of which are novel previously unmapped genes; 4 sequence tagged sites (STS) from microdissection; and 10 microsatellites from published linkage maps. This marker density substantially exceeds that on all available published bovine maps for this region and therefore represents a significant contribution to the global bovine genome mapping effort. Additionally, 12 BAC clones representing a defined sequence-ready pool of chromosome-specific DNA resource material were isolated using STS from chromosome microdissection. Comparative mapping analysis confirmed that the cattle Bta7 QTL is in a region of conserved synteny relative to two human chromosomes (Hsa19 and Hsa5) and five mouse chromosomes (Mmu8, Mmu9, Mmu11, Mmu17 and Mmu18). The linear order of genes within homology segments is generally conserved (particularly between cattle and humans), with few exceptions where gene order is conserved, but the conserved syntenic segments were inverted in orientation. A previously unknown small region of homology between the Bta7 trypanotolerance QTL and the murine Tir1 trypanotolerance QTL region on chromosome 17 (Mmu17) is also revealed. The size of this region is approximately 342 kb as estimated from the construction of a BAC contig. One of the BAC clones in this region of homology (RP42-102G22) defines a novel evolutionary breakpoint of conserved synteny between the bovine and the mouse genomes. At least nine novel candidate genes, the majority of which are implicated in innate immunity, were identified within the 95% confidence interval of the Bta7 QTL region. These genes have been implicated in: relaying information about infection to transcription factors which up-regulate the transcription of genes involved in innate immune responses (ECSIT and MAP2K7); regulation of gene expression and RNA processing (ELAVL1, EIF3S4 and HNRPM4); B-cell proliferation (particularly memory B-cells) and immunoglobulin secretion (8D6 Antigen/LOC51293); leukocyte migration (SCYA25); haematopoiesis (HSPC240); and free radical mediated destruction of phagocytosed parasites (ACP5). Amongst these genes, HNRPM4, 8D6 Antigen and HSPC240 are located in the region homology between the trypanotolerance QTL on Bta7 and the Tir1 QTL on Mmu17. In addition, a cluster of cytokine genes, plausibly involved in humoral and acquired immune responses was also mapped to the distal portion of the QTL region. The results reported in this thesis have demonstrated the vital role played by comparative genomics in accelerating gene discovery

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