Changes from natural forests and bush lands to various land use types has been shown to have great influence on soil structure and carbon storage. However, little is still known about how these changes affect soil aggregate stability and C storage over the long-term, especially in Africa. A study was conducted in central highlands of Kenya to evaluate the influence of four land use types on soil aggregation and aggregates C content, as affected by the abundance of earthworms and termites. The four land use types included: (1) an undisturbed natural bush land dotted with Lantana camara L. shrubs and Croton macrostachyus Hochst. ex Delile. trees, (2) over 50 years old grazed pasture dominated by a mixture of Bermuda grass (Cynodon dactylon (L.) Pers.) and Kikuyu grass (Pennisetum clandestinum Hochst. ex Chiov.), (3) over 80 years old coffee plantation with Coffea arabica L. cv. SL 28, and (4) a maize field that had been cultivated continuously for the last 3 years. Sampling for soil aggregates and soil macrofauna was done using monolith method to a depth of 0.3 m. Separation of stable soil aggregates was done through wet sieving process, where seven aggregate fractions were obtained; large macroaggregates (LM), small macroaggregates (SM), microaggregates (m), silt and clay (s+c), coarse particulate organic matter (cPOM), microaggregates-within-macroaggregates (mM) and silt and clay within macroaggregates (s+cM). The aggregate C content was analyzed using wet oxidation method. Soil macrofauna were handpicked from the monolith soil and preserved in 75% ethanol and identified to genera or species where possible, using morpho-anatomical keys and comparison with reference collections. It was hypothesized that soil aggregates and aggregate C would decrease with increasing level of soil disturbance, with the magnitude of these effects being reduced by the abundance of earthworms and termites. Generalized linear models (GLM) were used to test the effects of land use types on aggregate fractions and aggregate-associated C using R statistical x software However, to test the effects of the two factors on soil macrofauna data, negative binomial regression was chosen as an extension of the Poisson distribution. When analysis of variance (ANOVA) showed significant effects, Tukey’s post-hoc tests were performed at α = 0.05. Results showed that land use types had significant influence on soil aggregation. Notable differences were observed in large macroaggregates (LM) fraction, with higher weight in bush land (14.4 g 100 g-1 soil) and grazed pasture (12.4 g100 g-1 soil) compared to coffee plantation (3.9 g 100 g-1 soil) and maize field (0.6 g100 g-1 soil). On the contrary, microaggregate fraction weight was higher in maize field (41.2 g 100 g-1 soil) and lowest in bush land (18.8 g 100 g-1 soil). Land use type also had significant effects on soil aggregate-associated C, with the differences similar to those of the aggregate fractions. Among the soil macrofauna recovered, myriapods was the only group that showed significant differences, where Spirostreptidae sp. showed the highest abundance in bush land (149.3 individuals m2 ) compared to grazed pasture (42.7 individuals m2 ) coffee plantation (53.3 individuals m2 ) and maize field (5.3 individuals m2 ). Soil macrofauna considered ‘ecosystem engineers’ (earthworms and termites), and have been suggested to have significant effects on soil aggregation also showed no significant differences. Their abundance also showed weak or no correlation with soil aggregates and aggregate-associated C content across the land use types. This study shows the significance of land use change in shaping soil aggregation process and soil C content which could have far-reaching implications on the long-term C storage in the soil. This could be important especially in the tropics where mitigation and adaptation to climate change are ideally closely linked due to the critical importance of soil C for crop production

Integrated Soil Fertility Management (ISFM) has been recommended to address challenges of low soil fertility, by incorporating locally available organic resources (ORs) together with inorganic nitrogen (N) fertilizers. Despite ISFM success in field trials, there is limited information on ORs contribution to atmospheric greenhouse gas concentrations through nitrous oxide (N2O) emission. A short-term field study was conducted at two sites with different soil types; silt loam (Aludeka) and silty-clay soil (Sidada), to determine the effects of selected ORs (Calliandra carothyrsus (CL), farmyard manure (FYM) and maize stover (MS)) and their combination with inorganic N fertilizer on soil N2O emissions, available soil nitrogen and maize yields. The study also evaluated the relationship between N2O emissions and soil organic carbon (SOC), total nitrogen (TN), soil temperature, moisture content, soil nitrate (NO3 - ) and ammonium (NH4 + ). Static manual chambers were set up in the field to collect gas samples to quantify soil N2O emission. Relative to the control (0.19±0.1 Kg N2O-N ha-1 ), cumulative N2O emissions were significantly (P= 0.01) higher by 6, 9 and 13 fold under MS +N (1.05±0.8 Kg N2O-N ha-1 ), FYM +N (1.74±0.8 Kg N2O-N ha-1 ) and CL +N (2.54±1.2 Kg N2O-N ha-1 ), respectively at the Aludeka. At Sidada, cumulative N2O emissions were similar across all the treatments (P = 0.149). Approximately 240% and 411% of increase in cumulative N2O emissions across treatments at Sidada and Aludeka, respectively, was related to inorganic N fertilizer application. At Aludeka, cumulative N2O emissions exhibited significant positive relationship with SOC (r = 760, P = 0.029), TN (r = 0.820, P = 0.013), NO3 - (r = 0.905, P = 0.002) and NH4 + (r = 0.738, P = 0.036), and negatively correlated with soil C:N ratio (r = -0.710, P = 0.049), soil pH (r = -0.739, P=0.036). At Sidada only NO3- (r = 0.711, P =0.048) exhibited a significant positive correlation with cumulative N2O emissions. In terms of grain yield at Aludeka, there was a significant (P < 0.001) effect of treatments on maize grain yield, with no observed significant effect at Sidada (P>0.05). FYM +N treatment recorded the highest mean maize grain yield at both Aludeka (10.63 t ha−1 ) and Sidada (9.23 t ha−1 ). In Aludeka site, treatments with ORs in combination with inorganic N fertilizers increased maize grain yield in comparison with those without. The study suggests that influence of OR on N2O emissions in maize based-cropping system vary depending on the type of soil and increases when OR are applied in combination with inorganic N fertilizers. A more understanding of the prevailing environmental soil conditions especially on soil texture is necessary for finding the best treatment combination in terms of yield and N2O emission reduction under the ISFM approach.

Abstract

Contamination of crops with fumonisin leads to huge losses in cereals and negatively impacts on human health, animal productivity and international trade. Management of fumonisin contamination in maize has been a challenge since there are no effective management measures for Fusarium ear rots and lack of resistant maize varieties. This study was conducted with the objective of determining the efficacy of Aflasafe KE01 on the population of Fusarium species and fumonisin contamination of maize. The study was carried out in Wote, Kaiti, Kathiani and Nzambani sub counties of Makueni, Kitui and Machakos Counties, respectively. Twenty four maize fields were selected in each of the sub county where 12 fields were treated with Aflasafe KE01, while 12 fields comprised the untreated controls. The formulation comprised of four atoxigenic Aspergillus flavus on sterile sorghum seeds. Aflasafe KE01 was applied at a rate of 5 kg/ha and 10kg/ha by hand broadcasting in the maize fields two to three weeks before tussling of the maize. Soil samples were collected from each field prior to application of Aflasafe while maize grain samples were collected at harvest. Fusarium species were isolated from the ground maize and soil samples using pour plate method following serial dilution on low strength potato dextrose agar (PDA) and Spezieller Nahrstoffarmer Agar (SNA). Fusarium species growing were identified based on their cultural and morphological characteristics such as septation and sporophores, spore shape, pigmentation, mycelia color and colony pigmentation. Fumonisin in the maize samples was determined using Accuscan Pro-reader enzyme-linked immunosorbent assay (ELISA). The Fusarium species isolated from soil and maize samples at high frequency were F. verticillioides, F. proliferatum, F. chlamydosporum, F. merismoides, F. semitectum and F. oxysporum. Fusarium verticillioides was isolated at highest frequencies across the four sub counties. Maize samples from Aflasafe KE01 treated maize fields had significantly lower population of the Fusarium species compared to untreated maize fields across all the four sub counties. The mean incidence of F. verticillioides was 43% and 40.9% in the maize grains sampled from fields treated with Aflasafe KE01 at the rate 5 kg/ha and 10kg/ha, respectively; while the control fields corresponding to the 5 kg/ha and 10kg/ha application rates had mean incidences of 63% and 54.8%, respectively. There was significant reduction of up to 68.7% in the fumonisin levels in maize samples from Aflasafe KE01 treated compared to the untreated maize fields. The population of Fusarium species and fumonisin levels were significantly different among the study areas following Aflasafe KE01 application. About 62.5% of the maize fields treated with 5kg/ha of Aflasafe KE01 met the European commission regulatory threshold of ≤2ppmfor total fumonisin as compared to about 45% from the control fields. The results showed that application of Aflasafe KE01 effectively displaced the toxigenic Fusarium species in maize resulting in reduction of fumonisin in the maize from the Aflasafe KE01 treated fields by up to 68% compared to samples from untreated fields. This indicates that Aflasafe KE01 is a potential biopesticide for the biocontrol of Fusarium species and fumonisin production in maize. Efficacy of Aflasafe KE01 on reducing fumonisin contamination of other key staples in Kenya should be evaluated. Key words: Fusarium species, fumonisins, Aflasafe KE01, maize, atoxigenic Aspergillus sp.

The study investigated 1) the effect of in vitro pre-treatment of sunflower meal (SM) and wheat middlings (WM) using fiber degrading enzymes (FDE) without or with protease on mono-sugars release, organic acid concentration (SCFA), organic matter solubilisation, protein solubilization and apparent disappearance (AD) of neutral detergent fiber (NDF). Each feedstuff was mixed with 1% of FDE without or with protease in a ratio of 1:4 wt/wt for feedstuff:water, incubated for 24h and 48h at 40˚C, and freeze-dried. 2) Impact of the inclusion of pre-treated sunflower (TSM) and wheat middling (TWM) in a maize-soybean meal (MSBM) ration on growth performance, tibia attributes, apparent retention (AR) of components and caecal sugars and short-chain fatty acids production. A total of 288 Ross-708 d old male broiler chicks were placed in cages (6 birds/cage) based on body weight (BW) and allocated to 6 diets in a completely randomized design giving 8 replicates per diet. The diets were: I) PC, a MSBM, positive control (PC), II) NC, PC plus untreated sunflower meal (USM) and wheat middling (UWM), and III) 4 test diets in which USM and UWM were replaced with TSM and TWM at 25% (N25), 50% (N50), 75% (N75) and 100% (N100). For pre-treatment, each feedstuff was mixed with 1% of FDE in a ratio of 1:2 wt/wt for feedstuff:water, incubated for 24h at 40˚C, and oven-dried. All diets had titanium dioxide (0.3%) for AR determination. The body weight (BW), feed intake (FI), and mortality were recorded. Excreta was collected and frozen (-20℃). The data were subjected to PROC GLIMMIX of SAS 9.4, and LS means were separated using the Tukey test (P<0.05). The analyses of freeze-dried samples showed improved in-vitro solubilisation of organic matter, increased mono-sugars, organic acids concentration, protein solubilization, and AD of NDF in both SM and WM. Analyses of oven-dried samples showed that pre-treatment increased soluble protein (SP) and decreased neutral detergent protein (NDF-P) and NDF in TWM. Compared to 2 USM, TSM had less SP while NDF-P and NDF were greater. The overall BW and BW gain (BWG) of NC were lesser than PC throughout the study (P ≤0.001). The N75 and N100 BW and BW gain were less than PC (P ≤0.001) throughout the trial. Overall feed intake was not different during the starter, finisher, and overall period (P ≥0.217) relative to PC and NC. Also, feed conversion ratios were not different throughout the study (P ≥0.151). The NC tibia attributes were not different from PC throughout the trial; test diets tibia length was lesser than PC (P = 0.005) and had a linear decrease response with higher inclusion levels (P = 0.004) on d42. The test diets did not affect the AR of CP (P = 0 <0.001); there was decreased apparent NDF retention on d 21 and d 42 (P ≤0.001) and apparent gross energy retention on d 21 and d 42 (P ≤ 0.001) compared to PC. The NC and TD did not affect caecal sugars and SCFA production throughout the feeding period. In conclusion, pre-treating increased in vitro digestibility of sunflower meal and wheat middling, but their pre-treatment did not improve broiler chicken performance and AR of components

Drought is an important abiotic stress in the tropics that highly constrains sorghum production. Sorghum landraces and wild relatives have been known to harbor sources of novel genes but there is hardly any information about their drought tolerance performance during the post flowering period based on the stay green trait. There is need to characterize this stay green expressed drought tolerance and transfer the mapped QTLs into drought susceptible farmer preferred varieties. This research aimed at identifying sorghum genotypes that have the stay green trait through phenotypic and molecular characterization and subsequently, introgress the stay green QTL from mapped donor lines into farmer preferred varieties. This characterization was done phenotypically and also with Diversity array technology (DArT) molecular markers in genotypes grown under well irrigated and induced drought stress conditions. The trials in the field were set in an alpha lattice design of 12*8 replicated three times. The backcross progenies were genotyped using DArT markers. The genotypes and water regimes used had effects on various traits and helped to identify stay green genotypes. Nine genotypes, namely OKABIR, LODOKA, IESV92043 DL, IESV21400 DL, IESV23010 DL, IESV23006 DL, AKUOR-ACHOT, GBK 016109, GBK 048156 outperformed the check varieties, B35 and E36-1 and in their relative chlorophyll content, whereas the genotypes namely, IBUSAR, LODOKA, GBK 047293 AKUOR-ACHOT, OKABIR, F6YQ212, GBK 048917 had more green leaves at maturity than B35 and E36-1 in drought induced conditions. Ten genotypes, namely, AKUOR-ACHOT, LODOKA, GBK 045827, GBK 047293, WAHI IESV23010 DL, IESV23006 DL, IESV92043 DL, GBK 016114, OKABIR that outperformed B35 when ranked using Relative chlorophyll content measurements yielded higher than both B35 and E36-1 which were the check varieties. LODOKA a landrace, recorded the highest chlorophyll content, highest number of green leaves at maturity and a yielded 2.2 tons ha-1. The accessions whose yield was higher than B35 and E36-1 and B35 and also had higher GLAM and RCC values were chosen as novel sources of stay green. The results also indicated the possibility of finding stay-green alleles from wild genotypes with five wild genotypes, namely, GBK016114, GBK045827, GBK016109, GBK048922, GBK047293 that also clustered separately from B35 and E36-1 in the Neighbor Joining tree. The high significant positive correlation coefficients observed between the relative chlorophyll content and number of green leaves at maturity confirmed that the stay green trait was exhibited as functional stay green. High broad sense heritability estimates of the relative chlorophyll content (0.61) and the number of green leaves at maturity (0.64), indicated the influence of additive gene effects. The narrow sense heritability estimates for the quantity of green leaves at maturity (0.52) and for the relative chlorophyll content (0.45) also indicated the likelihood of a high positive response to selection. This study also identified 20 informative SNP markers that were highly polymorphic and were well distributed across the genome. The F2 genotypes from parental lines, ICSV 111 IN and LODOKA gave high general combining ability (GCA) for relative chlorophyll content and number of green leaves at maturity. Backcrossing for the stay green trait from mapped donor lines into farmer preferred varieties was successful with over 50% of the genotypes having greater than 75% recovery of the genome of the recurrent parent in the first backcross. These genotypes will form a strong basis for selection of superior drought tolerant sorghum varieties and the potential of improving susceptible sorghum genotypes for drought tolerance through marker assisted breeding

Pain and inflammation are the commonest manifestations of various pathologies, and are associated with high morbidities, debility, and economic strife globally, especially in underdeveloped regions of sub-Saharan Africa. The currently available conventional analgesic and anti-inflammatory drugs cause serious side effects, some of which are life threatening, are unaffordable, and unavailable to all patients, especially in low-income countries, hence the need for better alternatives. In the current study, the in vivo anti-inflammatory, analgesic, and in vitro cytotoxic activities of the Phytexponent preparation comprising the ethanolic extracts of Viola tricolor, Echinacea purpurea, Allium sativum, Matricaria chamomilla, and Triticum repens were investigated. The carrageenaninduced paw oedema technique was adopted to investigate the anti-inflammatory activity of the Phytexponent in experimental mice, at doses of 15.625 mg/Kg BW, 31.25 mg/Kg BW, 62.5 mg/Kg BW, 125 mg/Kg BW, 250 mg/Kg BW and 500 mg/Kg BW, with Indomethacin (10 mg/Kg BW) as positive control drug. The paw sizes of respective animals were measured using a plethysmographic technique, and the values used to calculate the percentage reduction in oedematous paw size, as an indicator of anti-inflammatory activity of the Phytexponent. The acetic acid-induced writhing technique was used to determine the analgesic activity of the Phytexponent in experimental Swiss albino mice at similar doses as those used for anti-inflammatory assay and indomethacin (4 mg/Kg BW) as the reference drug. Then, the number of wriths were recorded and expressed as the percentage inhibition of writhing. The standard 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide (MTT) assay technique was used to investigate the in vitro cytotoxic effects of the Phytexponent in Vero E6 cell line with cyclophosphamide as a positive cytotoxic agent. The percentage inhibitions of cell proliferation (percentage cytotoxicity) were determined according to a standard procedure. The study findings revealed that the Phytexponent preparation exerted significant anti-inflammatory effects in carrageenan-induced paw oedema mouse model, which ranged from 1.117±0.193% at the first hour to 11.162±0.091% at the fourth hour, at a dose of 31.25 mg/Kg BW, 6.240±0.242 % at the first hour to 17.407±0.186% at the fourth hour at a dose of 62.60 mg/Kg BW, 9.645±0.020% at the first hour to 31.795±0.090% at the fourth hourat a dose of 125 ,g/Kg BW, and 14.000±0.102% at the first hour to 37.931±0.133% in the fourth hour, at a dose of 250 mg/Kg BW (p<0.05). Notably, the Phytexponent significantly inhibited inflammation in a doseand time-dependent manner (p<0.05). The Phytexponent preparation exhibited significant analgesic activity (p<0.05) in experimental mice as depicted by reduced writhing frequencies (high percentage inhibitions of acetic acid-induced writhing), which increased from 55.054±0.174% at a dose of 31.25 mg/Kg BW to 94.982±0.098% at a dose of 250 mg/Kg BW, in a dose-dependent manner (p<0.05). The Phytexponent exhibited significantly higher analgesic activity at doses of 125 mg/Kg BW (75.924±0.253%) and 250 mg/Kg BW (94.982±0.098%) than indomethacin (64.786±0.098%), indicating higher analgesic efficacy. The Phytexponent preparation was not cytotoxic to Vero E6 cells as indicated by high CC50 value (>1000 µg/ml) compared to cyclophosphamide (CC50= 2.48µg/ml). The present study indicated that the Phytexponent formulation has significant in vivo anti-inflammatory and analgesic activities in mice models and is not cytotoxic to Vero E6 cell line. Therefore, based on the study findings, the Phytexponent formulation is a potential source of safe analgesic and anti-inflammatory associated phytocompounds. Further empirical studies, determination of mode(s) of anti-inflammatory and analgesic efficacy, and safety of the Phytexponent and its bioactive phytochemicals should be undertaken.

African Trypanosomosis is a major neglected tropical disease of animals and humans in low resource settings in Africa. The disease is cyclically transmitted by Glossina (tsetse flies) spp. and mechanically by biting flies such as Tabanus spp. and Stomoxys spp. and has enormous negative effects on the health and life of both humans and animals. The socio-economic and health impact of the disease is often felt at the edge of protected, tsetse-infested wildlife areas. In Rwanda, tsetse flies and trypanosomosis are reported in areas around the Akagera National Park but the situation has previously not been well documented. This study aimed at determining (i) the distribution of species of Glossina (ii) the Trypanosoma species circulating in tsetse flies, their infection rate, and the endosymbionts, (iii) the hosts’ preference for the tsetse flies, and (iv) the Trypanosoma species circulating in cattle, at the wildlife-livestock interface of Akagera National Park in Rwanda. To determine the distribution of Glossina, a longitudinal stratified sampling entomological survey was carried out inside the park and its surroundings. Biconical traps were deployed in 55 sites for six consecutive days of each study month from May 2018 to June 2019 and emptied every 48hours. Flies caught in the traps were identified using FAO keys for entomological taxonomy. The number of flies per trap per day (FTD) was used to determine the apparent density (AD) of the flies. Pearson chi-square (χ2) and parametrical tests (t-test and ANOVA) were used to determine the variability between the variables. Logistic regression was used to determine the association between predictors of tsetse flies occurrence. A selected sample of 1101 tsetse flies, recovered from the traps, was analysed for trypanosome species and endosymbionts using PCR, and 2-gene High Resolution Melting analysis for blood meal source. A total of 1037 blood samples collected between March and July 2019 from randomly selected cattle (local and local x Friesian breeds) in four districts neighboring the National Park, and were examined for species of Trypanosoma. Four districts viz. Kayonza, Gatsibo, Nyagatare and Kirehe were selected for their proximity to the park and for being adjacent to protected game reserves in Tanzania. The presence of trypanosomes in the blood samples was determined by microscopy, immunological rapid test, and PCR coupled with High-Resolution Melt (HRM) analysis. Sanger sequencing was done on the amplicons to complement the analysis. The Cohen Kappa test was used to compare the level of agreement between the diagnostic methods. Thirty-nine thousands and five hundreds sixteen (39,516) tsetse flies were collected using the traps, of which 73.4% (29,019) and 26.6% (10,497) were from inside the park and the interface area, respectively. Female flies accounted for 61.3% (24,223) while 38.7% (15,293) were males. Two species of Glossina, i.e. G. pallidipes [n=29,121, 7.4 flies/trap/day (FTD)] and G. morsitans centralis (n=10,395; 2.6 FTD) were identified. The statistical difference was significant between the two species (p=0.000). The flies were more abundant during the wet season (15.8 FTD) than the dry season (4.2 FTD) [p=0.000]. Large numbers of flies were trapped around the swamp areas (69.1 FTD) inside the park and in Nyagatare District (11.2 FTD) at the interface [p=0.000]. One thousand and one hundred and one (1101) tsetse flies (771 Glossina pallidipes and 330 Glossina morsitans centralis) were analysed for trypanosome infections. The overall infection rate was 13.9% (153/1101) in the head and proboscis (HP) and 24.3% (268/1101) in thorax and abdomen (TA) of the flies. Eight species of trypanosomes were identified. For each species, head +proboscis and thorax+ abdomen were analyzed in parallel and are presented as HP/TA. Of these species, Trypanosoma (T.) brucei brucei accounted for 4.1/7.1%, T.congolense Kilifi (2.2/2.1%), T.congolense savannah (1.6/1.2%), T. evansi (0/0.9%), T.godefreyi (1.2/3.1%), T. grayi (0/1.08%), T.simiae (2.08/3.7%), T.theileri (0/2.08%) and T.vivax (5.2/3.7%). Mixed infections were 2.2/0.8% (25/9). No T.brucei rhodesiense was found in tsetse flies analyzed. The endosymbionts found in tsetse flies were the bacteria Sodalis (2.8%; 31/1101) and Wolbachia (4.8%; 53/1101). No Spiroplasma and SGH Virus were found in all samples analyzed. The preferred hosts for blood meal by the tsetse flies were buffalo (36.5%), warthog (14.1%), cattle (10.6%), savannah elephant (8.7%), bushbuck (7.3%), and human (5.7%). The overall prevalence of trypanosome infections in cattle was 5.6%, 7.1%, and 18.7% by thin blood smear, Buffy coat technique, and PCR/HRM, respectively. Microscopy showed a low sensitivity (28.9%) while the rapid test (VerY Diag) showed a low specificity (32.5%). Trypanosomes were detected in cattle blood, including species that are pathogenic to cattle (i.e. T. brucei brucei, T. congolense savannah, T. evansi and T. vivax) and T. theileri which is nonpathogenic. T. congolense was the most prevalent (10.7%), followed by T. vivax 5.2%, T. brucei brucei 2%, and T. evansi 0.7% by PCR/HRM analysis. Lower trypanosome infections were observed in Ankole Friesian cross-breeds than indigenous Ankole. No human-infective T. brucei rhodesiense was detected. There was no significant difference between the mean PCV of infected and non-infected animals (p>0.162). The study results on tsetse distribution, endosymbionts, hosts preference, and trypanosomes infections, corroborate other similar regional findings. Glossina pallidipes were found in higher numbers and therefore conceivably the most important vectors of trypanosomes. This study confirms that the cattle reared around the Akagera NP are infected by Trypanosoma species causing African Animal Trypanosomiasis (AAT), and the area should, therefore, be targeted in control activities. Future studies should focus on the AAT impact assessment on cattle production and information on the use of trypanocides to help policymakers prioritize target areas and optimize intervention strategies.

Abstract