I am an agronomist-cum-stored product entomologist with bias towards botanical pesticides as alternatives to synthetic pesticides in smallholder agriculture in the tropics. Phone: +254 722 892504/738 412 218 Address: P.O. Box 536-20115
Egerton, Kenya
A study was conducted onfarm in Yala division, Siaya district, in 1996 and 1997 to determine the ... more A study was conducted onfarm in Yala division, Siaya district, in 1996 and 1997 to determine the critical starter inorganic nitrogen rate for increased maize productivity under Striga hermonthica infestation. Starter N treatments were laid out in randomized complete blocks with three ...
The data presented here provide information on the effect of selected botanical insecticides and ... more The data presented here provide information on the effect of selected botanical insecticides and field margin vegetation on aphids and their natural enemies' in dolichos bean, <em>Lablab purpureus</em>, under field conditions.
Laboratory studies were conducted to evaluate the fumigant and repellent properties of essential ... more Laboratory studies were conducted to evaluate the fumigant and repellent properties of essential oils extracted from the leaves of Ocimum americanum L. against five storage insects, Sitophilus oryzae L., Rhyzopertha dominica F., Tribolium castaneum (Herbst) and Callosobruchus chinensis F. Each essential oil was tested at four (0, 1, 5 and 10 µl/L air) and five (0, 0.5, 1.0, 1.5 and 2.0 µl oil/ g grain) rates in space fumigation and choice bioassay studies, respectively, with four replicates per treatment. In space fumigation studies, leaf essential oil at 10 µl/L air 24 h after treatment, caused 88.8, 87.5, 11.3 and 100% kill of S. oryzae, R. dominica, T. castaneum and C. chinensis insects, respectively, whose corresponding LC50 values were 0.38, 0.49, NS and 0.18 µl/L air, respectively. The LC50 values varied with plant part from which the essential oil was extracted. Leaf essential oil was most efficacious (0.18-0.49 µl/L air) followed by fruit (1.15-15.07 µl/L air) and stem (3.70...
Research Application Summary Insect pests attacking stored food grains cause substantial losses t... more Research Application Summary Insect pests attacking stored food grains cause substantial losses that undermine food security in sub-Sahara Africa. Subsistence farmers predominantly use traditional plant-based products to protect their grains in storage. In an attempt to seek alternatives to synthetic fumigants, laboratory screening of essential oil constituents were conducted to evaluate their fumigant toxicity against five stored-product insects, Sitophilus oryzae L., Rhyzopertha dominica F., Tribolium castaneum (Herbst), Oryzaephilus surinamensis L. and Callosobruchus chinensis F. Five essential oil constituents, ahumulene, caryophyllene oxide, myrcene, R(+)-apinene and R(+)-âpinene were each evaluated at four (0, 1, 5 and 10 μl/L air) rates in space fumigation chambers with four replicates per concentration. Results revealed a strong dose-, insect speciesand time-dependent fumigant toxicity in which caryophyllene oxide, myrcene, ahumulene, R(+)-apinene and R(+)-âpinene caused 18-...
Sustainable maize production in sub-Sahara Africa causing 20-80% grain yield losses. Although eff... more Sustainable maize production in sub-Sahara Africa causing 20-80% grain yield losses. Although effective synthetic pesticides are available, the smallholder farmers are yet to fully integrate them in their crop production practices hence the need for scientific rationalization of indigenous pest management options. Aqueous extracts (0, 0.85 and 1.70% w/v) and crude powders (0, 15 and 30 kg/ha) of three botanicals, Lantana camara L., Tephrosia vogelii Hook, Tagetes minuta L. were evaluated for efficacy against stem borers and their effects on productivity of a maize-bean intercrop. Field experiments were laid out in a randomized complete block design (RCBD) with three replicates per site. Results from the field bioassay trials showed that application of crude powders of T. vogelii, T. minuta and general plant ash at 15-30 kg/ha reduced (P<0.005) the stem borer population by 18-63% and increased (P<0.05) the maize grain yields by 30-70% (1.971-2.577 ton/ha) compared to the untrea...
Stripe rust, caused by the fungal pathogen Puccinia striiformis f. sp. tritici, is a major threat... more Stripe rust, caused by the fungal pathogen Puccinia striiformis f. sp. tritici, is a major threat to wheat (Triticum spp.) production worldwide. The objective of this study was to determine the virulence of P. striiformis f. sp. tritici races prevalent in the main wheat growing regions of Kenya, which includes Mt. Kenya, Eastern Kenya, and the Rift Valley (Central, Southern, and Northern Rift). Fifty P. striiformis f. sp. tritici isolates collected from 1970 to 1992 and from 2009 to 2014 were virulence phenotyped with stripe rust differential sets, and 45 isolates were genotyped with sequence characterized amplified region (SCAR) markers to differentiate the isolates and identify aggressive strains PstS1 and PstS2. Virulence corresponding to stripe rust resistance genes Yr1, Yr2, Yr3, Yr6, Yr7, Yr8, Yr9, Yr17, Yr25, and Yr27 and the seedling resistance in genotype Avocet S were detected. Ten races were detected in the P. striiformis f. sp. tritici samples obtained from 1970 to 1992,...
ABSTRACT The fumigant and repellent effects of Ocimum gratissimum L. oil and its constituents, β-... more ABSTRACT The fumigant and repellent effects of Ocimum gratissimum L. oil and its constituents, β-(Z)-ocimene and eugenol, were evaluated against adults of Sitophilus oryzae (L.), Tribolium castaneum (Herbst), Oryzaephilus surinamensis (L.), Rhyzopertha dominica (F.) and Callosobruchus chinensis (L.). The fumigant toxicities of the oil and two of its constituents were assessed at four rates (0, 1, 5 and10 μL/L air) in space fumigation, whereas repellence of the oil and eugenol in acetone was evaluated in choice bioassays at five rates (0, 1.0, 2.0, 3.0 and 4.0 μL oil/2 g grain). Results showed that fumigant toxicity and repellence of the oil and its constituents were significantly (P&lt;0.0001) influenced by concentration and time after treatment. At 1 μL/L air, the oil caused 98%, 99% and 100% mortality of R. dominica, O. surinamensis and C. chinensis, respectively, 24 h after treatment, whereas eugenol achieved 79%, 61% and 100% kill of the same insects. β-(Z)-ocimene produced a weaker toxicity with 8%, 11% and 59% mortality of R. dominica, O. surinamensis and C. chinensis, respectively. Except for T. castaneum which was more tolerant, LC50 values for tested insects ranged from 0.20 to 14, 0.01 to 17 and 0.80 to 23 μL/L air 24 h after treatment for O. gratissimum oil, eugenol and β-(Z)-ocimene, respectively. All test insects had percentage repellence (PR) values which ranged from 37.5% to 100% and 45% to 100% for the oil and eugenol, respectively. However, C. chinensis showed a dose-dependent decrease in PR values in the eugenol bioassay with a corresponding dose-dependent mortality on treated grains. Ocimum gratissimum oil and its constituents are potential alternatives to synthetic fumigants in the treatment of durable agricultural products. Successful adoption of plant oils in the protection of food commodities promises an eco-friendly option compatible with international biosafety regulations.
BACKGROUND Hymenopteran parasitoids provide key natural pest regulation services and are reared c... more BACKGROUND Hymenopteran parasitoids provide key natural pest regulation services and are reared commercially as biological control agents. Therefore, understanding parasitoid community composition in natural populations is important to enable better management for optimized natural pest regulation. We carried out a field study to understand the parasitoid community associated with Aphis fabae on East African smallholder farms. Either common bean (Phaseolus vulgaris) or lablab (Lablab purpureus) sentinel plants were infested with A .fabae and deployed in 96 fields across Kenya, Tanzania, and Malawi. RESULTS A total of 463 parasitoids emerged from sentinel plants of which 424 were identified by mitochondrial cytochrome oxidase I (COI) barcoding. Aphidius colemani was abundant in Kenya, Tanzania and Malawi, while Lysiphlebus testaceipes was only present in Malawi. The identity of A. colemani specimens were confirmed by sequencing LWRh and 16S genes and was selected for further genetic and population analyses. A total of 12 A. colemani haplotypes were identified. Of these, 9 were from our East African specimens and 3 from the Barcode of Life Database (BOLD). CONCLUSION A. colemani and L. testaceipes are potential targets for conservation biological control in tropical smallholder agro-ecosystems. We hypothesize that high genetic diversity in East African populations of A. colemani suggests that this species originated in East Africa and has spread globally due to its use as a biological control agent. These East African populations could have potential for use as strains in commercial biological control or to improve existing A. colemani strains by selective breeding. This article is protected by copyright. All rights reserved.
African Journal of Environmental Science and Technology, 2009
A farm survey was conducted in three representative administrative districts of the Lake Victoria... more A farm survey was conducted in three representative administrative districts of the Lake Victoria Basin (LVB), Kenya to document farmers’ indigenous knowledge and the factors that influence the use of botanicals instead of synthetic insecticides in insect pest management. A total of 65 farm households were randomly sampled using stratified sampling procedure. The maximum likelihood log model was used to determine factors that influence use of botanical and synthetic insect pest control methods (PCM). Results revealed that female gender as household head (HH) and age significantly ( P < .001) increased the likelihood of a household using botanical PCM in the field by 0.15 and 0.021, respectively. In storage, female gender and severity of pest infestation significantly ( P < .001) increased the probability of a household using botanical insecticide by 0.814 and 0.738, respectively. On the contrary, education of HH (0.342) and ownership of title to land (0.512) significantly ( P ...
Food insecurity, caused by poor storage and post-harvest handling techniques, is one the major ch... more Food insecurity, caused by poor storage and post-harvest handling techniques, is one the major challenges in Sub-Saharan Africa. The food situation is worsened by insect pests that cause up to 40% preand post-harvest food grain losses. Yet food production mainly at subsistence level making use of modern pest management options, especially the synthetic pesticides, uneconomical. In an effort to contain the insect pest threat in stored agricultural products, a number of aromatic genetic resources have been screened for bioactivity against major coleopteran pests of stored food grains and promising species for botanical pesticides identified. This study therefore, assessed the grain fumigation, contact toxicity and reproduction inhibition under controlled conditions. Percentage mortality data was homogenized through angular transformations before being subjected to ANOVA and means were separated using Tukey’s HSD test. Probit regression analyses of transformed dose-responses were used ...
African Journal of Traditional, Complementary and Alternative Medicines, 2009
Extracts of pines have diverse physiological and pharmacological actions, its buds, needles and b... more Extracts of pines have diverse physiological and pharmacological actions, its buds, needles and bark are used in phytotherapy.Geographical, seasonal, age-related, inter-population differencies of volatile compounds in the needles were defined. Wider surveys of the needle essential oil composition under the different type of soils are still scarse. Despite Scots pine is the prevailing tree in the forests of Lithuania, little is known about its essential oils. The aim of our study was to evaluate the essential oil composition in the needles of Scots pine (Pinus sylvestris L.) growing on arenosols (3 sites), luvisols (3 sites) and histosols (3 sites). Current-year and one-year-old needles of 8 pines in each site were sampled in July, 2005. Volatile components of the needles were extracted and analyzed by GC and GC/MS. Seventy one identified component made up 89.1-95.1 % of total oil content. The most predominant fraction was found to be monoterpenes (19.0-40.0 %), with pinene (6.1-26.1...
The effect of ground powders of two tropical plants, Lantana camara L. and Tephrosia vogelii Hook... more The effect of ground powders of two tropical plants, Lantana camara L. and Tephrosia vogelii Hook, on the level of insect damage and the grain quality parameters of stored maize were evaluated for five months. The evaluations were aimed at generating natural product treatments suitable for post-harvest grain protection and as sustainable alternatives to synthetic insecticides in the control of the maize weevil, Sitophilus zeamais Motschulsky. Three rates (1.0, 2.5 and 5.0% w/w) of each plant powder, a synthetic insecticide, Actellic Super 2% dust at 0.05% w/w and an untreated control were used as treatments. Results showed that the plant powders significantly minimised the magnitude of depression in percent grain moisture content albeit at a lesser rate with high concentration and had no effect on the percent germination of maize grains when compared to the controls. The botanical treatments and synthetic insecticide were equally effective in reducing insect damage by 25%, but the l...
African Journal of Environmental Science and Technology, 2009
Agriculture in Lake Victoria basin (LVB) in Tanzania is predominantly subsistence and is characte... more Agriculture in Lake Victoria basin (LVB) in Tanzania is predominantly subsistence and is characterised by perennial food deficits, cyclic famines and poverty prompted largely by unreliable rainfall patterns, declining soil fertility and food grains pests and diseases. The pest problem is more pronounced as farmers are yet to fully integrate synthetic pesticides into their insect pest management systems due to subsistence nature of production and high poverty levels that make them rely on indigenous knowledge (IK) systems to meet their needs. The survey was conducted to document farmers’ IK on management of key field and storage insect pests in Magu and Misungwi districts in the LVB, Tanzania. Major crops grown were maize, rice, sorghum, finger millet, bean, groundnut, cowpea, green gram, brassicas, chicken pea, cassava, sweet potato, cotton and vegetables. Crops were mainly infested by Busseola fusca (Lepidoptera: Noctuidae), Spodoptera spp (Lepidoptera: Noctuidae), Agrotis spp (Lep...
Wheat stripe rust, caused by Puccinia striiformis f. sp. tritici (Pst), is one of the key disease... more Wheat stripe rust, caused by Puccinia striiformis f. sp. tritici (Pst), is one of the key diseases of economic importance in wheat worldwide. Host resistance, which follows the gene-for-gene hypothesis between the host and pathogen, has been used in wheat lines to resolve resistance specificities and postulate resistant genes. The objective of this study was to elucidate stripe rust resistance in a collection of Kenyan wheat lines and Watkin landraces to identify new sources of stripe rust (Yr) resistance. In this study, the resistance in twenty wheat lines was determined by comparing their infection type with those of twenty differential lines using isolates representing twelve Puccinia striiformis races from Kenya, Denmark, U.K., Sweden, and Eritrea at the seedling stage. Among the twenty wheat lines, none was resistant to all the twelve Pst races and isolate DK02d/12 (“Kranich” race) was virulent on all the genotypes except wheat genotype “Kenya Tai.” This genotype (“Kenya Tai”) ...
A study was conducted onfarm in Yala division, Siaya district, in 1996 and 1997 to determine the ... more A study was conducted onfarm in Yala division, Siaya district, in 1996 and 1997 to determine the critical starter inorganic nitrogen rate for increased maize productivity under Striga hermonthica infestation. Starter N treatments were laid out in randomized complete blocks with three ...
The data presented here provide information on the effect of selected botanical insecticides and ... more The data presented here provide information on the effect of selected botanical insecticides and field margin vegetation on aphids and their natural enemies' in dolichos bean, <em>Lablab purpureus</em>, under field conditions.
Laboratory studies were conducted to evaluate the fumigant and repellent properties of essential ... more Laboratory studies were conducted to evaluate the fumigant and repellent properties of essential oils extracted from the leaves of Ocimum americanum L. against five storage insects, Sitophilus oryzae L., Rhyzopertha dominica F., Tribolium castaneum (Herbst) and Callosobruchus chinensis F. Each essential oil was tested at four (0, 1, 5 and 10 µl/L air) and five (0, 0.5, 1.0, 1.5 and 2.0 µl oil/ g grain) rates in space fumigation and choice bioassay studies, respectively, with four replicates per treatment. In space fumigation studies, leaf essential oil at 10 µl/L air 24 h after treatment, caused 88.8, 87.5, 11.3 and 100% kill of S. oryzae, R. dominica, T. castaneum and C. chinensis insects, respectively, whose corresponding LC50 values were 0.38, 0.49, NS and 0.18 µl/L air, respectively. The LC50 values varied with plant part from which the essential oil was extracted. Leaf essential oil was most efficacious (0.18-0.49 µl/L air) followed by fruit (1.15-15.07 µl/L air) and stem (3.70...
Research Application Summary Insect pests attacking stored food grains cause substantial losses t... more Research Application Summary Insect pests attacking stored food grains cause substantial losses that undermine food security in sub-Sahara Africa. Subsistence farmers predominantly use traditional plant-based products to protect their grains in storage. In an attempt to seek alternatives to synthetic fumigants, laboratory screening of essential oil constituents were conducted to evaluate their fumigant toxicity against five stored-product insects, Sitophilus oryzae L., Rhyzopertha dominica F., Tribolium castaneum (Herbst), Oryzaephilus surinamensis L. and Callosobruchus chinensis F. Five essential oil constituents, ahumulene, caryophyllene oxide, myrcene, R(+)-apinene and R(+)-âpinene were each evaluated at four (0, 1, 5 and 10 μl/L air) rates in space fumigation chambers with four replicates per concentration. Results revealed a strong dose-, insect speciesand time-dependent fumigant toxicity in which caryophyllene oxide, myrcene, ahumulene, R(+)-apinene and R(+)-âpinene caused 18-...
Sustainable maize production in sub-Sahara Africa causing 20-80% grain yield losses. Although eff... more Sustainable maize production in sub-Sahara Africa causing 20-80% grain yield losses. Although effective synthetic pesticides are available, the smallholder farmers are yet to fully integrate them in their crop production practices hence the need for scientific rationalization of indigenous pest management options. Aqueous extracts (0, 0.85 and 1.70% w/v) and crude powders (0, 15 and 30 kg/ha) of three botanicals, Lantana camara L., Tephrosia vogelii Hook, Tagetes minuta L. were evaluated for efficacy against stem borers and their effects on productivity of a maize-bean intercrop. Field experiments were laid out in a randomized complete block design (RCBD) with three replicates per site. Results from the field bioassay trials showed that application of crude powders of T. vogelii, T. minuta and general plant ash at 15-30 kg/ha reduced (P<0.005) the stem borer population by 18-63% and increased (P<0.05) the maize grain yields by 30-70% (1.971-2.577 ton/ha) compared to the untrea...
Stripe rust, caused by the fungal pathogen Puccinia striiformis f. sp. tritici, is a major threat... more Stripe rust, caused by the fungal pathogen Puccinia striiformis f. sp. tritici, is a major threat to wheat (Triticum spp.) production worldwide. The objective of this study was to determine the virulence of P. striiformis f. sp. tritici races prevalent in the main wheat growing regions of Kenya, which includes Mt. Kenya, Eastern Kenya, and the Rift Valley (Central, Southern, and Northern Rift). Fifty P. striiformis f. sp. tritici isolates collected from 1970 to 1992 and from 2009 to 2014 were virulence phenotyped with stripe rust differential sets, and 45 isolates were genotyped with sequence characterized amplified region (SCAR) markers to differentiate the isolates and identify aggressive strains PstS1 and PstS2. Virulence corresponding to stripe rust resistance genes Yr1, Yr2, Yr3, Yr6, Yr7, Yr8, Yr9, Yr17, Yr25, and Yr27 and the seedling resistance in genotype Avocet S were detected. Ten races were detected in the P. striiformis f. sp. tritici samples obtained from 1970 to 1992,...
ABSTRACT The fumigant and repellent effects of Ocimum gratissimum L. oil and its constituents, β-... more ABSTRACT The fumigant and repellent effects of Ocimum gratissimum L. oil and its constituents, β-(Z)-ocimene and eugenol, were evaluated against adults of Sitophilus oryzae (L.), Tribolium castaneum (Herbst), Oryzaephilus surinamensis (L.), Rhyzopertha dominica (F.) and Callosobruchus chinensis (L.). The fumigant toxicities of the oil and two of its constituents were assessed at four rates (0, 1, 5 and10 μL/L air) in space fumigation, whereas repellence of the oil and eugenol in acetone was evaluated in choice bioassays at five rates (0, 1.0, 2.0, 3.0 and 4.0 μL oil/2 g grain). Results showed that fumigant toxicity and repellence of the oil and its constituents were significantly (P&lt;0.0001) influenced by concentration and time after treatment. At 1 μL/L air, the oil caused 98%, 99% and 100% mortality of R. dominica, O. surinamensis and C. chinensis, respectively, 24 h after treatment, whereas eugenol achieved 79%, 61% and 100% kill of the same insects. β-(Z)-ocimene produced a weaker toxicity with 8%, 11% and 59% mortality of R. dominica, O. surinamensis and C. chinensis, respectively. Except for T. castaneum which was more tolerant, LC50 values for tested insects ranged from 0.20 to 14, 0.01 to 17 and 0.80 to 23 μL/L air 24 h after treatment for O. gratissimum oil, eugenol and β-(Z)-ocimene, respectively. All test insects had percentage repellence (PR) values which ranged from 37.5% to 100% and 45% to 100% for the oil and eugenol, respectively. However, C. chinensis showed a dose-dependent decrease in PR values in the eugenol bioassay with a corresponding dose-dependent mortality on treated grains. Ocimum gratissimum oil and its constituents are potential alternatives to synthetic fumigants in the treatment of durable agricultural products. Successful adoption of plant oils in the protection of food commodities promises an eco-friendly option compatible with international biosafety regulations.
BACKGROUND Hymenopteran parasitoids provide key natural pest regulation services and are reared c... more BACKGROUND Hymenopteran parasitoids provide key natural pest regulation services and are reared commercially as biological control agents. Therefore, understanding parasitoid community composition in natural populations is important to enable better management for optimized natural pest regulation. We carried out a field study to understand the parasitoid community associated with Aphis fabae on East African smallholder farms. Either common bean (Phaseolus vulgaris) or lablab (Lablab purpureus) sentinel plants were infested with A .fabae and deployed in 96 fields across Kenya, Tanzania, and Malawi. RESULTS A total of 463 parasitoids emerged from sentinel plants of which 424 were identified by mitochondrial cytochrome oxidase I (COI) barcoding. Aphidius colemani was abundant in Kenya, Tanzania and Malawi, while Lysiphlebus testaceipes was only present in Malawi. The identity of A. colemani specimens were confirmed by sequencing LWRh and 16S genes and was selected for further genetic and population analyses. A total of 12 A. colemani haplotypes were identified. Of these, 9 were from our East African specimens and 3 from the Barcode of Life Database (BOLD). CONCLUSION A. colemani and L. testaceipes are potential targets for conservation biological control in tropical smallholder agro-ecosystems. We hypothesize that high genetic diversity in East African populations of A. colemani suggests that this species originated in East Africa and has spread globally due to its use as a biological control agent. These East African populations could have potential for use as strains in commercial biological control or to improve existing A. colemani strains by selective breeding. This article is protected by copyright. All rights reserved.
African Journal of Environmental Science and Technology, 2009
A farm survey was conducted in three representative administrative districts of the Lake Victoria... more A farm survey was conducted in three representative administrative districts of the Lake Victoria Basin (LVB), Kenya to document farmers’ indigenous knowledge and the factors that influence the use of botanicals instead of synthetic insecticides in insect pest management. A total of 65 farm households were randomly sampled using stratified sampling procedure. The maximum likelihood log model was used to determine factors that influence use of botanical and synthetic insect pest control methods (PCM). Results revealed that female gender as household head (HH) and age significantly ( P < .001) increased the likelihood of a household using botanical PCM in the field by 0.15 and 0.021, respectively. In storage, female gender and severity of pest infestation significantly ( P < .001) increased the probability of a household using botanical insecticide by 0.814 and 0.738, respectively. On the contrary, education of HH (0.342) and ownership of title to land (0.512) significantly ( P ...
Food insecurity, caused by poor storage and post-harvest handling techniques, is one the major ch... more Food insecurity, caused by poor storage and post-harvest handling techniques, is one the major challenges in Sub-Saharan Africa. The food situation is worsened by insect pests that cause up to 40% preand post-harvest food grain losses. Yet food production mainly at subsistence level making use of modern pest management options, especially the synthetic pesticides, uneconomical. In an effort to contain the insect pest threat in stored agricultural products, a number of aromatic genetic resources have been screened for bioactivity against major coleopteran pests of stored food grains and promising species for botanical pesticides identified. This study therefore, assessed the grain fumigation, contact toxicity and reproduction inhibition under controlled conditions. Percentage mortality data was homogenized through angular transformations before being subjected to ANOVA and means were separated using Tukey’s HSD test. Probit regression analyses of transformed dose-responses were used ...
African Journal of Traditional, Complementary and Alternative Medicines, 2009
Extracts of pines have diverse physiological and pharmacological actions, its buds, needles and b... more Extracts of pines have diverse physiological and pharmacological actions, its buds, needles and bark are used in phytotherapy.Geographical, seasonal, age-related, inter-population differencies of volatile compounds in the needles were defined. Wider surveys of the needle essential oil composition under the different type of soils are still scarse. Despite Scots pine is the prevailing tree in the forests of Lithuania, little is known about its essential oils. The aim of our study was to evaluate the essential oil composition in the needles of Scots pine (Pinus sylvestris L.) growing on arenosols (3 sites), luvisols (3 sites) and histosols (3 sites). Current-year and one-year-old needles of 8 pines in each site were sampled in July, 2005. Volatile components of the needles were extracted and analyzed by GC and GC/MS. Seventy one identified component made up 89.1-95.1 % of total oil content. The most predominant fraction was found to be monoterpenes (19.0-40.0 %), with pinene (6.1-26.1...
The effect of ground powders of two tropical plants, Lantana camara L. and Tephrosia vogelii Hook... more The effect of ground powders of two tropical plants, Lantana camara L. and Tephrosia vogelii Hook, on the level of insect damage and the grain quality parameters of stored maize were evaluated for five months. The evaluations were aimed at generating natural product treatments suitable for post-harvest grain protection and as sustainable alternatives to synthetic insecticides in the control of the maize weevil, Sitophilus zeamais Motschulsky. Three rates (1.0, 2.5 and 5.0% w/w) of each plant powder, a synthetic insecticide, Actellic Super 2% dust at 0.05% w/w and an untreated control were used as treatments. Results showed that the plant powders significantly minimised the magnitude of depression in percent grain moisture content albeit at a lesser rate with high concentration and had no effect on the percent germination of maize grains when compared to the controls. The botanical treatments and synthetic insecticide were equally effective in reducing insect damage by 25%, but the l...
African Journal of Environmental Science and Technology, 2009
Agriculture in Lake Victoria basin (LVB) in Tanzania is predominantly subsistence and is characte... more Agriculture in Lake Victoria basin (LVB) in Tanzania is predominantly subsistence and is characterised by perennial food deficits, cyclic famines and poverty prompted largely by unreliable rainfall patterns, declining soil fertility and food grains pests and diseases. The pest problem is more pronounced as farmers are yet to fully integrate synthetic pesticides into their insect pest management systems due to subsistence nature of production and high poverty levels that make them rely on indigenous knowledge (IK) systems to meet their needs. The survey was conducted to document farmers’ IK on management of key field and storage insect pests in Magu and Misungwi districts in the LVB, Tanzania. Major crops grown were maize, rice, sorghum, finger millet, bean, groundnut, cowpea, green gram, brassicas, chicken pea, cassava, sweet potato, cotton and vegetables. Crops were mainly infested by Busseola fusca (Lepidoptera: Noctuidae), Spodoptera spp (Lepidoptera: Noctuidae), Agrotis spp (Lep...
Wheat stripe rust, caused by Puccinia striiformis f. sp. tritici (Pst), is one of the key disease... more Wheat stripe rust, caused by Puccinia striiformis f. sp. tritici (Pst), is one of the key diseases of economic importance in wheat worldwide. Host resistance, which follows the gene-for-gene hypothesis between the host and pathogen, has been used in wheat lines to resolve resistance specificities and postulate resistant genes. The objective of this study was to elucidate stripe rust resistance in a collection of Kenyan wheat lines and Watkin landraces to identify new sources of stripe rust (Yr) resistance. In this study, the resistance in twenty wheat lines was determined by comparing their infection type with those of twenty differential lines using isolates representing twelve Puccinia striiformis races from Kenya, Denmark, U.K., Sweden, and Eritrea at the seedling stage. Among the twenty wheat lines, none was resistant to all the twelve Pst races and isolate DK02d/12 (“Kranich” race) was virulent on all the genotypes except wheat genotype “Kenya Tai.” This genotype (“Kenya Tai”) ...
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