Mathematical Modeling of Host - Pest Interactions in Stage-Structured Populations: A Case of False Codling Moth [Thaumatotibia leucotreta]

False codling moth (FCM) (Thaumatotibia lucotreta) is a significant pest due to its potential economic impact on many susceptible fruits in most temperate regions of the world. Efforts to control the codling moth in the past mostly relied on the use of broad spectrum insecticide sprays, which has resulted in the development of insecticide resistance, and the disruption of the control of secondary pests. Understanding the dynamic of this pest is of great in importance in order to effectively employ the most effective control strategies. In this study, a mathematical model of host-false codling moth interactions is developed and qualitatively analysed using stability theory of system of differential equations. The basic offspring number with respect to FCM free equilibrium is obtain using next generation matrix. The condition for local and global asymptotic stability of FCM free and coexistence equilibria are established. The model is analysed numerically and graphically represented to justify the analytical results

SCUAF - Version 4: A Model to Estimate Soil Changes Under Agriculture, Agroforestry and Forestry

Land Economics/Use,

Bovine in-vitro embryo production and its contribution towards improved food security in Kenya

The Boran breed is mainly kept by pastoralist communities as a source of both milk and beef, and by commercial beef ranches mainly for beef production. Although this breed Boran may seemingly be low valued, it can be raised to higher reproductive potential using current reproductive technologies such as in-vitro embryo production and embryo transfer. In this author’s literature search there was lack of locally optimized procedures for boosting the reproductive potential of the Boran cow using such technologies. This paper discusses simplified methods used for in-vitro embryo production and embryo transfer that have been tested and optimized for the Kenyan Boran cows as described in text. This article provides the reader with technical procedures, the outcomes and the challenges experienced during use of the technologies. The results of the reported in vitro embryo production obtained an oocyte maturation rate of over 90%, over 70% cleavage rate and an embryo output of 30-50% blastocyst rate. Embryo transfer had a conception rate of 45-50%. All the 17 calves born out of this work have since attained puberty without any abnormalities. This research was the first to produce a “test tube” calf in Kenya and built the capacity of 57 staff on these technical procedures within East Africa. Utilization of the in vitro embryo production technology in Kenya can be used to do value addition to indigenous cows and improve household incomes and food security. This avenue can be used to raise household revenues and attract many more farmers to engage in farming leading to improved national economic and food security. Kenya can utilize reproductive technologies in the dairy sector due to the massive potential benefits to revolutionize the sector for enhanced food security by increasing cattle productivity. The paper highlights practical ways of applying the technologies discussed therein to help raise the economy of the Kenyan livestock farmers and boost their food security. Key words: Reproductive Technologies, Boran cattle, Keny

Investigation of recent population bottlenecks in Kenyan wild sorghum populations (Sorghum bicolor (L.) Moench ssp. verticilliflorum (Steud.) De Wet) based on microsatellite diversity and genetic disequilibria

Identifying populations that have recently suffered a severe reduction in size is particularly important for their conservation as they are likely to suffer an increased risk of genetic erosion. We investigated the presence of recent bottlenecks in two wild sorghum populations from different eco-geographical conditions in Kenya employing 18 microsatellite markers. Microsatellite analysis showed high allelic diversity in the two populations, with a mean of 4.11 and 6.94 alleles per locus in the North-West wild sorghum population (NWWSP) and the South-East wild sorghum population (SEWSP), respectively. The mean observed heterozygosity was 0.34 and 0.56 in NWWSP and SEWSP, respectively. A large long-term effective populations size for both populations was observed assuming either an infinite allele model or a stepwise mutation model. There was no apparent loss of genetic variability for either of the populations. Test of heterozygosity excess indicated that a recent bottleneck in the two populations is highly unlikely. Furthermore, analysis of the allele frequency distribution revealed an L-shaped distribution which would not have been observed in case a recent bottleneck had reduced genetic variability in the two populations. The fact that most loci displayed a significant heterozygosity deficiency could be explained by population subdivision and the mixed mating system exhibited by wild sorghum populations. Furthermore, the possibility of a historical expansion of wild sorghum populations and presence of null alleles could not be ruled out

Wild Sorghums—Their Potential Use in Crop Improvement

Wild relatives of crops, sorghum being no exception, continue to play a key role in the development of high performing cultivars. Among the 22 species comprising this highly variable genus, only one, Sorghum bicolor, is commercially cultivated for food, feed and bioenergy production. The wild sorghums thus offer opportunities for further genetic enhancement of this crop. Profi table utilization of wild species however demands an inter-disciplinary, multi-pronged approach to increase the probability of achieving the desired genetic improvement. To this end, this chapter presents a review of the current knowledge on (1) biosystematic aspects such as botany, taxonomy and classifi cation, (2) domestication and evolution, including centers of diversity, genetic diversity, chromosome homologies and species/ phylogenetic relationships, (3) genetic resources, genepools and conservation perspectives including collections and preservation of germplasm, (4) utilization aspects including the specifi c potential of the wild species in crop improvement with reference to insect and disease resistance, yield, grain quality, ecological adaptation, allopatric resistance, and (5) strategies to maximize utilization of wild germplasm resources including direct hybridization, reproductive barriers and their circumvention, chromosome and physiological manipulation, the gaps between hybridization and utilization and molecular interventions. Recent advancements in biotechnology, in particular, are expected to increase the effi ciency and range of use of these wild sorghum species

LoanSTAR Energy Conservation Audits: January 1989 - August 1990

Fourteen audit reports, covering seventy buildings and Texas' Governor's mansion, have been accepted as a part of the Texas LoanSTAR Program. Task 1 (the first of five) is responsible for audit reviews and assignments. One hundred forty-five energy cost reduction measures (ECRMs) and maintenance and operation recommendations (M&Os) have been identified which can result in significant amounts of electrical energy, demand and natural gas savings. Costs savings are $1,882,000/yr and the investment cost is$5,566,000 for an overall simple payback of 3.0 years. The ECRMs and M&Os have been categorized as well as the types of buildings involved. The cost for auditing the 5.2 million square feet was $0.054 per square foot. Problems associated with audit reports are also discussed

Synthesis of Specimen Preparation and Curing Processes for Cold Recycled Asphalt Mixes

The process of cold recycling (CR) is becoming method of choice for pavement rehabilitation due to significantly added environmental and economic benefits. Understanding and standardization of specimen preparation and curing processes are critical to replicate field conditions in lab. This paper presents an extensive synthesis of various specimen preparation and curing processes for cold recycled asphalt mixes. Topics synthesized include RAP, emulsion/bitumen and aggregate preparation, mixing processes, pre- and post- compaction curing, compaction and mechanical testing. This paper was developed through efforts of cold recycling task group (TG6) of RILEM Technical Committee on Testing and Characterization of Sustainable Innovative Bituminous Materials and Systems (TC-SIB)

Genetic structure and relationships within and between cultivated and wild sorghum ( Sorghum bicolor (L.) Moench) in Kenya as revealed by microsatellite markers

Understanding the extent and partitioning of diversity within and among crop landraces and their wild/weedy relatives constitutes the first step in conserving and unlocking their genetic potential. This study aimed to characterize the genetic structure and relationships within and between cultivated and wild sorghum at country scale in Kenya, and to elucidate some of the underlying evolutionary mechanisms. We analyzed at total of 439 individuals comprising 329 cultivated and 110 wild sorghums using 24 microsatellite markers. We observed a total of 295 alleles across all loci and individuals, with 257 different alleles being detected in the cultivated sorghum gene pool and 238 alleles in the wild sorghum gene pool. We found that the wild sorghum gene pool harbored significantly more genetic diversity than its domesticated counterpart, a reflection that domestication of sorghum was accompanied by a genetic bottleneck. Overall, our study found close genetic proximity between cultivated sorghum and its wild progenitor, with the extent of crop-wild divergence varying among cultivation regions. The observed genetic proximity may have arisen primarily due to historical and/or contemporary gene flow between the two congeners, with differences in farmers' practices explaining inter-regional gene flow differences. This suggests that deployment of transgenic sorghum in Kenya may lead to escape of transgenes into wild-weedy sorghum relatives. In both cultivated and wild sorghum, genetic diversity was found to be structured more along geographical level than agro-climatic level. This indicated that gene flow and genetic drift contributed to shaping the contemporary genetic structure in the two congeners. Spatial autocorrelation analysis revealed a strong spatial genetic structure in both cultivated and wild sorghums at the country scale, which could be explained by medium- to long-distance seed movemen

Genetic structure and diversity of wild sorghum populations (Sorghum spp.) from different eco-geographical regions of Kenya

Wild sorghums are extremely diverse phenotypically, genetically and geographically. However, there is an apparent lack of knowledge on the genetic structure and diversity of wild sorghum populations within and between various eco-geographical regions. This is a major obstacle to both their effective conservation and potential use in breeding programs. The objective of this study was to assess the genetic diversity and structure of wild sorghum populations across a range of eco-geographical conditions in Kenya. Sixty-two wild sorghum populations collected from the 4 main sorghum growing regions in Kenya were genotyped using 18 simple sequence repeat markers. The study showed that wild sorghum is highly variable with the Coast region displaying the highest diversity. Analysis of molecular variance showed a significant variance component within and among wild sorghum populations within regions. The genetic structure of wild sorghum populations indicated that gene flow is not restricted to populations within the same geographic region. A weak regional differentiation was found among populations, reflecting human intervention in shaping wild sorghum genetic structure through seed-mediated gene flow. The sympatric occurrence of wild and cultivated sorghums coupled with extensive seed-mediated gene flow, suggests a potential crop-to-wild gene flow and vice versa across the regions. Wild sorghum displayed a mixed mating system. The wide range of estimated outcrossing rates indicate that some environmental conditions may exist where self-fertilisation is favoured while others cross-pollination is more advantageous