Members of the Goliathus group in the order Coleoptera, family Scarabaeidae and the sub-family Cetoniidae is one among essential ecological insects worldwide with scanty documentation in Tanzania. The country was amon...Members of the Goliathus group in the order Coleoptera, family Scarabaeidae and the sub-family Cetoniidae is one among essential ecological insects worldwide with scanty documentation in Tanzania. The country was among the first point of collection of the specimen by Moser (1909) but subsequent attempts to locate and collect the specimen were unsuccessful possibly due to changed habitat and behaviour of Goliathus. Much of published work about the insect are based on the morphological characteristics of collected specimen which led to designation of six major species namely;Goliathus goliatus, G. cacicus, G. regius, G. albosignatus, G. orientalis and G. usambarensis, the last two being considered to exist in Tanzania. The current study reports on successful identification of habitats using biological cues and subsequently collected several Goliathus specimen that had been difficult to trace for more than a century. New insights into correct identity of the species by using a combination of morphological and molecular techniques have been set. The study has resolved that only one species, Goliathus orientalis with five sub-species exist in Tanzania.展开更多
To investigate the effect of planting date, spacing and seeding methods on disease development and yield components ofrice, a factorial experiment in randomized complete block design （RCBD） with four replications wa...To investigate the effect of planting date, spacing and seeding methods on disease development and yield components ofrice, a factorial experiment in randomized complete block design （RCBD） with four replications was conducted during 2011 plantingseason at Izzi Local Government Area （LGA） of Ebonyi State, Nigeria. This experiment was carried out with four levels of plantingdates （early June, late June, early July and late July）, three levels of spacing （15, 20 and 25 cm） and two levels of seeding method（direct seeding and seedling transplanting）. The studied traits included plant height （PH）, number of tillers （NT）, leaf area （LA）, rootlength （RL）, panicle length （PL）, 1,000 seed weight （SW）, disease incidence and severity. The result showed that all the factors hadsignificant effect on the parameters measured. Sowing in early July had the highest LA of 65.38 cm^2, PH of 122.00 cm, RL of 29.04cm and TN of 10.54, and the second largest PL of 25.08 cm and SW of 25.12 g. Also sowing in early July had the highest diseaseseverity of 3.21, followed by 3.14 which occurred in late July, while the least 2.17 occurred in early June. The direct seeding methodhad the highest disease incidence of 70.83%, followed by plant spacing of 15 cm × 15 cm which had the disease incidence of 69.72%,while sowing in early June had the least disease incidence of 57.50%. In conclusion, planting of rice in Southeastern Nigeria shouldbe done in early July, as the yield components were significantly better than in other dates though with the highest disease severity.展开更多
Rice yellow mottle virus (RYMV) is a major biotic constraint for rice production in Africa. The resistance-breaking ability of Tanzanian RYMV strains and phylotypes (S4lm (Tz526), S4lv (Tz516), S4ug (Tz508), S5 (Tz429...Rice yellow mottle virus (RYMV) is a major biotic constraint for rice production in Africa. The resistance-breaking ability of Tanzanian RYMV strains and phylotypes (S4lm (Tz526), S4lv (Tz516), S4ug (Tz508), S5 (Tz429, Tz445), S6c (Tz486) and S6w (Tz539)) were tested by inoculating rice cultivars with RYMV1 resistant alleles (Gigante (rymv1-2), Tog12387 (rymv1-3), Tog5681 (rymv1-3), Tog5438 (rymv1-4), Tog5672 (rymv1-4+rymv2) and Tog5674 (rymv 1-5)) in a screen house. The results revealed multiple resistance-breaking strains and phylotypes on resistant cultivars Gigante, Tog12387, Tog5438 and Tog5681. However, the resistance breakdown was highly variable depending on the strain used, and disease severity ranged from 11% - 75.3%. The virulence potential of RYMV phylotype S4lm (Tz526) was similar to phylotype S6w (Tz539). The impact of strains and phylotypes on yield and its components in rice cultivars revealed highly significant differences (P ≤ 0.001). The lowest percent plant height reduction (2.8%), number of tillers per plant (2.5%), 1000 grain weight (2.7%), spikelet sterility (3.5%) and yield (5%) was recorded in rice cultivar Gigante inoculated with RYMV phylotype S6c (Tz486). Phylotype S6c (Tz486) despite being less virulent compared to other strains, its virus titer in rice cultivar Gigante (1.833) was higher than S5 (Tz429, Tz445) inoculated on Tog5674 (0.171, 0.207) and S6w (Tz539) inoculated on Tog5681 (0.283). The resistant-breaking strain S5 (Tz445) multiplied in resistant rice cultivar Tog5674 without inducing visible symptoms but showed positive reaction to ELISA with low virus titer. The strain S5 overcame wide range of resistant alleles including rymv1-2, rymv1-3, rymv1-4 and rymv1-5 resistance, with exception of rymv1-4 + rymv2. The current results gave a new perspective for future identification of resistance-breaking mutations through sequencing of the RYMV genome in infected rice cultivars and mutagenesis of an infectious viral clone useful for future RYMV resistant breeding programs.展开更多
This study was conducted to assess the incidence of seed-borne fungi on rice seeds sourced from the major rice growing areas of South-Eastern Nigeria. The rice seeds were collected during the dry seasons between 2009 ...This study was conducted to assess the incidence of seed-borne fungi on rice seeds sourced from the major rice growing areas of South-Eastern Nigeria. The rice seeds were collected during the dry seasons between 2009 and 2010. Four hundred rice seeds randomly collected and surface sterilized by washing in 3% sodium hypochlorite and rinsed two times with sterile distilled water were placed in three circular rings inside the Petri dishes. The incubation was done one after the other for each variety from all the locations. Ten fungi species from eight genera were isolated from the rice seeds in all the rice growing areas of South-Eastern Nigeria. The fungi pathogens vary from one locality to another, as well as the frequency of occurrence. The pathogens isolated include： Fusarium moniliforme, F. solani, F. oxysporium, Aspergillus spp., Botridiploidia spp., Helminthosporium spp., Penicillium spp., Trichoconis padwickii, Curvularia oryzae and Phoma oryzae. Though, there was the presence of some seed-borne fungi in the rice seeds from the areas studied, most of the cultivars experienced up to 90% germination. But some cultivars had very low germination. IR 1416 from Arochukwu and GB90 from Arondiuzogu had less than 1% germination. This study shows that seed-borne organisms are major constraint in rice production in the South-Eastern states of Nigeria as a result of low seed germination stemmed from infestation of fungi organisms in the seeds.展开更多
The sweetpotato production in Tanzania has been increasing due to the changing status of the crop from famine relief to a commercial crop particularly in the central zone of Tanzania.Production of the crop is affected...The sweetpotato production in Tanzania has been increasing due to the changing status of the crop from famine relief to a commercial crop particularly in the central zone of Tanzania.Production of the crop is affected by environmental and biotic stresses.Apart from prolonged drought which affects timely availability of planting materials,sweetpotato weevils were recently reported by growers as a major setback to the productivity of the crop.The study was conducted between December 2016 and July 2017 in Gairo and Ikungi Districts of Morogoro and Singida regions respectively.The aim was to identify sweetpotato weevil species existing in the area,determine the seasonal abundance of the pests and test the response of popular and farmers’preferred sweetpotato varieties to the pest.The effect of planting time on the abundance of sweetpotato weevils was also studied.It was established that Cylas puncticollis is the lone weevil species infesting the crop in the study area.Time of planting significantly(p<0.05)influenced weevils’abundance with early planted crop sustaining least number of pests compared to the late planted.Sweetpotato variety,Gudugudu was least damaged by C.puncticollis.Locational influence suggested that Gairo District sustained greater weevil abundance and associated damages compared to Ikungi District.It was concluded that planting dates had influence on seasonal abundance of sweetpotato weevil with early planted crop sustaining least infestation with C.puncticollis compared to late planted crop.展开更多
Coffee (Coffea arabica L.) is a crop of major economic significance in Tanzania with annual revenue estimated at 100 Million USD. The current mean annual production of the crop is 68,000 MT of clean coffee of which 90...Coffee (Coffea arabica L.) is a crop of major economic significance in Tanzania with annual revenue estimated at 100 Million USD. The current mean annual production of the crop is 68,000 MT of clean coffee of which 90% is contributed by about 450,000 smallholder farmers and while large estate owners contribute the rest. Antestia bug (Antestiopsis orbitalis spp.), the pest known to attack all vegetative and fruiting parts of the coffee tree with substantial yield reduction of up to 45% has been reported to occur contemporary on Arabica coffee in Tanzania, particularly in Kilimanjaro Region. Despite the reported existence of Antestia bug and its damages that badly inflict on the productivity and quality of coffee, the pest status of the bug in Tanzania has never been established. The present study examined the incidence damage severity of Antestia bug in the Arabica coffee fields in major producing regions of Kilimanjaro, Ruvuma and Songwe. A stratified sampling of 360 coffee farms was done on which the Antestia bug incidence and severity were recorded. Results suggested that all regions were infested and the shade intensity influenced the pest incidences with the highest severity record in Kilimanjaro and the least affected was Songwe Region. Dense shade had the highest Antestia bug incidence than sparse shade canopy (p < 0.001). The current study sheds insights into understanding the pest status of Antestia bugs on Arabica coffee in Tanzania which could be used in designing effective management strategies. .展开更多
Effects of Commiphora swynnertonii,Synadenium glaucescens and Allium sativum extracts on the tomato leaf miner,Tuta absoluta(Meyrick)were evaluated on the adults and in screen house conditions.The adult stage was invo...Effects of Commiphora swynnertonii,Synadenium glaucescens and Allium sativum extracts on the tomato leaf miner,Tuta absoluta(Meyrick)were evaluated on the adults and in screen house conditions.The adult stage was involved with 30 adults that were reared in an insectarium,the experimental design was a completely randomized design(plant extracts from three plants species×three doses of 2%,4% and 8%).In the screen house,experimental dispositive was a completely randomized block design(two varieties of tomatoes×three plants extracts).Larval counts were performed after 0,1,2,3 and 7 d of treatment,40 tomato leaves(10×4 replicates)were randomly taken from each treatment.The mean percentage mortality of adults was recorded daily for 5 d.Results indicated that,each plant extract caused significant mortality to adults of T.absoluta after 5 d in comparison to the control.Leaf dipping against adult of T.absoluta proved to be the most effective for all plant extracts at 30%-100%.Commiphora resulted in the adults’mortality of 100%.In the screen house Commiphora showed the high reduction of infestation for Tanya and Cal J varieties.Treatment with this plant extract resulted in the highest fruit yield and the lowest yield loss compared to all the plant extracts.C.swynnertonii extract is recommended into integrated pest management strategies for the control of T.absoluta.展开更多
This research tries to demonstrate physiological effect of combined infection of two viruses on growth parameter of cowpea plant as demonstrated through symptom expression. Blackeye cowpea mosaic virus(BlCMV) and Cucu...This research tries to demonstrate physiological effect of combined infection of two viruses on growth parameter of cowpea plant as demonstrated through symptom expression. Blackeye cowpea mosaic virus(BlCMV) and Cucumber mosaic virus(CMV) were transmitted to cowpea plants by mechanical rub inoculation. This study showed that the differences in stem height and final aboveground fresh weight of cowpea plants inoculated with mixed infection with CMV and BlCMV were significantly less than those of plants inoculated with a single virus. Likewise cowpea plants inoculated with either virus alone or with CMV and BlCMV mixed infection had less stem height and aboveground fresh weight than the control. The mixed infection of BlCMV and CMV caused significant increase in the severity of symptoms in cowpea and also in the height using factors analysis and Abbott's equation. Symptom severity rating scale used, demonstrated statistical proof for physiological effect based on symptom severity for co-infection. A three phase disease symptom severity expression revealed disease severity for each viral treatment associated with host plant.展开更多
文摘Members of the Goliathus group in the order Coleoptera, family Scarabaeidae and the sub-family Cetoniidae is one among essential ecological insects worldwide with scanty documentation in Tanzania. The country was among the first point of collection of the specimen by Moser (1909) but subsequent attempts to locate and collect the specimen were unsuccessful possibly due to changed habitat and behaviour of Goliathus. Much of published work about the insect are based on the morphological characteristics of collected specimen which led to designation of six major species namely;Goliathus goliatus, G. cacicus, G. regius, G. albosignatus, G. orientalis and G. usambarensis, the last two being considered to exist in Tanzania. The current study reports on successful identification of habitats using biological cues and subsequently collected several Goliathus specimen that had been difficult to trace for more than a century. New insights into correct identity of the species by using a combination of morphological and molecular techniques have been set. The study has resolved that only one species, Goliathus orientalis with five sub-species exist in Tanzania.
文摘To investigate the effect of planting date, spacing and seeding methods on disease development and yield components ofrice, a factorial experiment in randomized complete block design （RCBD） with four replications was conducted during 2011 plantingseason at Izzi Local Government Area （LGA） of Ebonyi State, Nigeria. This experiment was carried out with four levels of plantingdates （early June, late June, early July and late July）, three levels of spacing （15, 20 and 25 cm） and two levels of seeding method（direct seeding and seedling transplanting）. The studied traits included plant height （PH）, number of tillers （NT）, leaf area （LA）, rootlength （RL）, panicle length （PL）, 1,000 seed weight （SW）, disease incidence and severity. The result showed that all the factors hadsignificant effect on the parameters measured. Sowing in early July had the highest LA of 65.38 cm^2, PH of 122.00 cm, RL of 29.04cm and TN of 10.54, and the second largest PL of 25.08 cm and SW of 25.12 g. Also sowing in early July had the highest diseaseseverity of 3.21, followed by 3.14 which occurred in late July, while the least 2.17 occurred in early June. The direct seeding methodhad the highest disease incidence of 70.83%, followed by plant spacing of 15 cm × 15 cm which had the disease incidence of 69.72%,while sowing in early June had the least disease incidence of 57.50%. In conclusion, planting of rice in Southeastern Nigeria shouldbe done in early July, as the yield components were significantly better than in other dates though with the highest disease severity.
文摘Rice yellow mottle virus (RYMV) is a major biotic constraint for rice production in Africa. The resistance-breaking ability of Tanzanian RYMV strains and phylotypes (S4lm (Tz526), S4lv (Tz516), S4ug (Tz508), S5 (Tz429, Tz445), S6c (Tz486) and S6w (Tz539)) were tested by inoculating rice cultivars with RYMV1 resistant alleles (Gigante (rymv1-2), Tog12387 (rymv1-3), Tog5681 (rymv1-3), Tog5438 (rymv1-4), Tog5672 (rymv1-4+rymv2) and Tog5674 (rymv 1-5)) in a screen house. The results revealed multiple resistance-breaking strains and phylotypes on resistant cultivars Gigante, Tog12387, Tog5438 and Tog5681. However, the resistance breakdown was highly variable depending on the strain used, and disease severity ranged from 11% - 75.3%. The virulence potential of RYMV phylotype S4lm (Tz526) was similar to phylotype S6w (Tz539). The impact of strains and phylotypes on yield and its components in rice cultivars revealed highly significant differences (P ≤ 0.001). The lowest percent plant height reduction (2.8%), number of tillers per plant (2.5%), 1000 grain weight (2.7%), spikelet sterility (3.5%) and yield (5%) was recorded in rice cultivar Gigante inoculated with RYMV phylotype S6c (Tz486). Phylotype S6c (Tz486) despite being less virulent compared to other strains, its virus titer in rice cultivar Gigante (1.833) was higher than S5 (Tz429, Tz445) inoculated on Tog5674 (0.171, 0.207) and S6w (Tz539) inoculated on Tog5681 (0.283). The resistant-breaking strain S5 (Tz445) multiplied in resistant rice cultivar Tog5674 without inducing visible symptoms but showed positive reaction to ELISA with low virus titer. The strain S5 overcame wide range of resistant alleles including rymv1-2, rymv1-3, rymv1-4 and rymv1-5 resistance, with exception of rymv1-4 + rymv2. The current results gave a new perspective for future identification of resistance-breaking mutations through sequencing of the RYMV genome in infected rice cultivars and mutagenesis of an infectious viral clone useful for future RYMV resistant breeding programs.
文摘This study was conducted to assess the incidence of seed-borne fungi on rice seeds sourced from the major rice growing areas of South-Eastern Nigeria. The rice seeds were collected during the dry seasons between 2009 and 2010. Four hundred rice seeds randomly collected and surface sterilized by washing in 3% sodium hypochlorite and rinsed two times with sterile distilled water were placed in three circular rings inside the Petri dishes. The incubation was done one after the other for each variety from all the locations. Ten fungi species from eight genera were isolated from the rice seeds in all the rice growing areas of South-Eastern Nigeria. The fungi pathogens vary from one locality to another, as well as the frequency of occurrence. The pathogens isolated include： Fusarium moniliforme, F. solani, F. oxysporium, Aspergillus spp., Botridiploidia spp., Helminthosporium spp., Penicillium spp., Trichoconis padwickii, Curvularia oryzae and Phoma oryzae. Though, there was the presence of some seed-borne fungi in the rice seeds from the areas studied, most of the cultivars experienced up to 90% germination. But some cultivars had very low germination. IR 1416 from Arochukwu and GB90 from Arondiuzogu had less than 1% germination. This study shows that seed-borne organisms are major constraint in rice production in the South-Eastern states of Nigeria as a result of low seed germination stemmed from infestation of fungi organisms in the seeds.
文摘The sweetpotato production in Tanzania has been increasing due to the changing status of the crop from famine relief to a commercial crop particularly in the central zone of Tanzania.Production of the crop is affected by environmental and biotic stresses.Apart from prolonged drought which affects timely availability of planting materials,sweetpotato weevils were recently reported by growers as a major setback to the productivity of the crop.The study was conducted between December 2016 and July 2017 in Gairo and Ikungi Districts of Morogoro and Singida regions respectively.The aim was to identify sweetpotato weevil species existing in the area,determine the seasonal abundance of the pests and test the response of popular and farmers’preferred sweetpotato varieties to the pest.The effect of planting time on the abundance of sweetpotato weevils was also studied.It was established that Cylas puncticollis is the lone weevil species infesting the crop in the study area.Time of planting significantly(p<0.05)influenced weevils’abundance with early planted crop sustaining least number of pests compared to the late planted.Sweetpotato variety,Gudugudu was least damaged by C.puncticollis.Locational influence suggested that Gairo District sustained greater weevil abundance and associated damages compared to Ikungi District.It was concluded that planting dates had influence on seasonal abundance of sweetpotato weevil with early planted crop sustaining least infestation with C.puncticollis compared to late planted crop.
文摘Coffee (Coffea arabica L.) is a crop of major economic significance in Tanzania with annual revenue estimated at 100 Million USD. The current mean annual production of the crop is 68,000 MT of clean coffee of which 90% is contributed by about 450,000 smallholder farmers and while large estate owners contribute the rest. Antestia bug (Antestiopsis orbitalis spp.), the pest known to attack all vegetative and fruiting parts of the coffee tree with substantial yield reduction of up to 45% has been reported to occur contemporary on Arabica coffee in Tanzania, particularly in Kilimanjaro Region. Despite the reported existence of Antestia bug and its damages that badly inflict on the productivity and quality of coffee, the pest status of the bug in Tanzania has never been established. The present study examined the incidence damage severity of Antestia bug in the Arabica coffee fields in major producing regions of Kilimanjaro, Ruvuma and Songwe. A stratified sampling of 360 coffee farms was done on which the Antestia bug incidence and severity were recorded. Results suggested that all regions were infested and the shade intensity influenced the pest incidences with the highest severity record in Kilimanjaro and the least affected was Songwe Region. Dense shade had the highest Antestia bug incidence than sparse shade canopy (p < 0.001). The current study sheds insights into understanding the pest status of Antestia bugs on Arabica coffee in Tanzania which could be used in designing effective management strategies. .
文摘Effects of Commiphora swynnertonii,Synadenium glaucescens and Allium sativum extracts on the tomato leaf miner,Tuta absoluta(Meyrick)were evaluated on the adults and in screen house conditions.The adult stage was involved with 30 adults that were reared in an insectarium,the experimental design was a completely randomized design(plant extracts from three plants species×three doses of 2%,4% and 8%).In the screen house,experimental dispositive was a completely randomized block design(two varieties of tomatoes×three plants extracts).Larval counts were performed after 0,1,2,3 and 7 d of treatment,40 tomato leaves(10×4 replicates)were randomly taken from each treatment.The mean percentage mortality of adults was recorded daily for 5 d.Results indicated that,each plant extract caused significant mortality to adults of T.absoluta after 5 d in comparison to the control.Leaf dipping against adult of T.absoluta proved to be the most effective for all plant extracts at 30%-100%.Commiphora resulted in the adults’mortality of 100%.In the screen house Commiphora showed the high reduction of infestation for Tanya and Cal J varieties.Treatment with this plant extract resulted in the highest fruit yield and the lowest yield loss compared to all the plant extracts.C.swynnertonii extract is recommended into integrated pest management strategies for the control of T.absoluta.
基金support received from the virology laboratory of the International Institute of Tropical Agriculture (IITA) Ibadan, Oyo State, Nigeria
文摘This research tries to demonstrate physiological effect of combined infection of two viruses on growth parameter of cowpea plant as demonstrated through symptom expression. Blackeye cowpea mosaic virus(BlCMV) and Cucumber mosaic virus(CMV) were transmitted to cowpea plants by mechanical rub inoculation. This study showed that the differences in stem height and final aboveground fresh weight of cowpea plants inoculated with mixed infection with CMV and BlCMV were significantly less than those of plants inoculated with a single virus. Likewise cowpea plants inoculated with either virus alone or with CMV and BlCMV mixed infection had less stem height and aboveground fresh weight than the control. The mixed infection of BlCMV and CMV caused significant increase in the severity of symptoms in cowpea and also in the height using factors analysis and Abbott's equation. Symptom severity rating scale used, demonstrated statistical proof for physiological effect based on symptom severity for co-infection. A three phase disease symptom severity expression revealed disease severity for each viral treatment associated with host plant.
