Browsing by Author "Akotsen-Mensah, C."
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Item Behavioral Response of Plum Curculio, Conotrachelus nenuphar, to Synthetic Fruit Volatile Lures and the Male-Produced Aggregation Pheromone(Hindawi Publishing Corporation, Psyche, 2015-10-15) Akotsen-Mensah, C.; Fadamiro, H.Y.Plum curculio, Conotrachelus nenuphar Herbst (Coleoptera: Curculionidae), is a key pest of stone and pome fruits in North America. The behavioral response of adults of different physiological states (sex, age, diet, andmating status) to three commercially available synthetic lures, benzaldehyde (BZ) and plum essence (PE), the male-produced aggregation pheromone, grandisoic acid (GA), or their combinations, was studied in the laboratory. Four choice olfactometer bioassays demonstrated significant attraction of both sexes to PE lure. Both BZ and GA lures were not attractive to plum curculio when tested as commercially formulated. PE had higher release rate (1.51mg/hr) than BZ (0.36mg/hr) and GA (ca. 0.04mg/hr), suggesting that the higher attractiveness of PE may be due to its relatively higher release rates. Tests with combined lures showed a neutral effect of combining GA with PE and an inhibitory effect of combining BZ with PE. The physiological conditions of the weevils had no significant effect on their response to the lures. Olfactometer tests with pure 1,2,4-trichlorobenzene (TCB) confirmed that this compound was inhibitory to plum curculio. These results are discussed in relation to the contrasting field reports which implicated BZ + GA as an effective attractant for plum curculio.Item Can yield variability be explained? Integrated assessment of maize yield gaps across smallholders in Ghana(Field Crops Research, 2019-03-29) Adjei-Nsiah, S.; van Loon, M.P.; Descheemaeker, K.; Akotsen-Mensah, C.; van Dijk, M.; Morley, T.; van Ittersum, M.K.; Reidsma, P.Agricultural production in Ghana should more than double to fulfil the estimated food demand in 2050, but this is a challenge as the productivity of food crops has been low, extremely variable and prone to stagnation. Yield gap estimations and explanations can help to identify the potential for intensification on existing agricultural land. However, to date most yield gap analyses had a disciplinary focus. The objective of this paper is to assess the impact of crop management, soil and household factors on maize (Zea mays) yields in two major maize growing regions in Ghana through an integrated approach. We applied a variety of complementary methods to study sites in the Brong Ahafo and Northern region. Farm household surveys, yield measurements and soil sampling were undertaken in 2015 and 2016. Water-limited potential yield (Yw) was estimated with a crop growth simulation model, and two different on-farm demonstration experiments were carried out in 2016 and 2017. There is great potential to increase maize yields across the study sites. Estimated yield gaps ranged between 3.8 Mg ha−1 (67% of Yw) and 13.6 Mg ha−1 (84% of Yw). However, there was no consistency in factors affecting maize yield and yield gaps when using complementary methods. Demonstration experiments showed the potential of improved varieties, fertilizers and improved planting densities, with yields up to 9 Mg ha−1. This was not confirmed in the analysis of the household surveys, as the large yield variation across years on the same farms impeded the disclosure of effects of management, soil and household factors. The low-input nature of the farming system and the incidence of fall armyworm led to relatively uniform and low yields across the entire population. So, farmers’ yields were determined by interacting, and strongly varying, household, soil and management factors. We found that for highly variable and complex smallholder farming systems there is a danger in drawing oversimplified conclusions based on results from a single methodological approach. Integrating household surveys, crop growth simulation modelling and demonstration experiments can add value to yield gap analysis. However, the challenge remains to improve upon this type of integrated assessment to be able to satisfactorily disentangle the interacting factors that can be managed by farmers in order to increase crop yields.Item Can yield variability be explained? Integrated assessment of maize yield gaps across smallholders in Ghana(Field Crops Research, 2019-04) van Loon, M.P.; Adjei-Nsiah, S.; Descheemaeker, K.; Akotsen-Mensah, C.; van Dijk, M.; Morley, T.; van Ittersum, M.K.; Reidsma, P.Agricultural production in Ghana should more than double to fulfil the estimated food demand in 2050, but this is a challenge as the productivity of food crops has been low, extremely variable and prone to stagnation. Yield gap estimations and explanations can help to identify the potential for intensification on existing agricultural land. However, to date most yield gap analyses had a disciplinary focus. The objective of this paper is to assess the impact of crop management, soil and household factors on maize (Zea mays) yields in two major maize growing regions in Ghana through an integrated approach. We applied a variety of complementary methods to study sites in the Brong Ahafo and Northern region. Farm household surveys, yield measurements and soil sampling were undertaken in 2015 and 2016. Water-limited potential yield (Y w ) was estimated with a crop growth simulation model, and two different on-farm demonstration experiments were carried out in 2016 and 2017. There is great potential to increase maize yields across the study sites. Estimated yield gaps ranged between 3.8 Mg ha ⁻¹ (67% of Y w ) and 13.6 Mg ha ⁻¹ (84% of Y w ). However, there was no consistency in factors affecting maize yield and yield gaps when using complementary methods. Demonstration experiments showed the potential of improved varieties, fertilizers and improved planting densities, with yields up to 9 Mg ha ⁻¹ . This was not confirmed in the analysis of the household surveys, as the large yield variation across years on the same farms impeded the disclosure of effects of management, soil and household factors. The low-input nature of the farming system and the incidence of fall armyworm led to relatively uniform and low yields across the entire population. So, farmers’ yields were determined by interacting, and strongly varying, household, soil and management factors. We found that for highly variable and complex smallholder farming systems there is a danger in drawing oversimplified conclusions based on results from a single methodological approach. Integrating household surveys, crop growth simulation modelling and demonstration experiments can add value to yield gap analysis. However, the challenge remains to improve upon this type of integrated assessment to be able to satisfactorily disentangle the interacting factors that can be managed by farmers in order to increase crop yields.Item Effect of some climatic factors on insects associated with citrus agro-ecosystems in Ghana(Journal of Biodiversity and Env. Science (JBES) Vol. 5, No. 4, p 428-436, 2014) Aidoo, O.F.; Kyerematen, R.; Akotsen-Mensah, C.; Afreh-Nuamah, K.The present study investigates the effects of some climatic factors on insects associated with citrus orchards in two different agro-ecological zones in Ghana. The study showed that, climatic factors affected insects differently in different agro-ecological zones. There was a negative and highly significant (P˂0.01) correlation between insect abundance and rainfall in the Coastal Savannah zone whereas the correlation between mean temperature and insect abundance was negative and significant (P˂0.05) in the Semi-Deciduous Rain Forest zone. Numbers of insect species peaked differently in some months during the study period due to favourable climatic conditions for their reproduction, growth and activities. The month of February was most favourable for the insects in the Semi-Deciduous Rain Forest zone whiles January was most favourable for the Coastal Savannah zone. Similarly, some months were more favourable for pests of citrus in Ghana; January and February for Ceratitis ditissima and Leptoglossus sp. in both agro-ecological zones and, January and February for Achaea sp. in the Semi-Deciduous Rain Forest and Coastal Savannah respectively. The months of October and September were most favourable for Zonocerus variegatus in the Coastal Savannah zone and Semi-deciduous rain forest zone respectively during the study period. Even though the two different agro-ecological zones had common pests, the proportions and peak periods however varied. The differences are crucial with regards to developing integrated pests management strategies to control insect pests of citrus in Ghana.Item Ghana IPM programme: Past, present and future(Outlooks on Pest Management, 2015-02) Afreh-Nuamah, K.; Akotsen-Mensah, C.Recent developments have shown that Integrated Pest Management (IPM) could be more practical and field oriented to the benefits of the ordinary farmer. The authors have personally come to accept the fact that promoting IPM is also about empowering users to engage in competitive and sustainable agricultural and horticultural production with long-term positive impacts on hunger and environmental health. The Farmers? Field School (FFS) training methodology which we embraced in Ghana in 1995, originated from the FAO Intercountry programme in Asia where it had been used to train over one million rice farmers in integrated pest management strategies. The FFS is an emerging extension tool for promoting integrated pest management, because of the growing realization that future agricultural growth for resource-poor farmers should be knowledge intensive to be able to deal with complex environments with varied characteristics often specific to a particular location. The IPM/FFS training distinguishes itself from conventional IPM extension packages by its participatory and farmer centred approach. Farmers gain fundamental understanding of the agro ecosystem and economy of their crops on which they base their own crop management decisions. In Ghana, it was discovered that more than 80% of farmers trained during the first IPM/FFS programme under the FAO Technical Co-operation Programme (TCP) funded pilot project in rice production conducted in five irrigated sites in Ghana (Dawhenya, Tono, Botanga, Vea and Afife) changed their practices and adopted the IPM strategies. During the scaling up programme funded by UNDP through the FAO, an impact assessment study observed that with FFS, crop yields rose by a mean of 150% whilst losses dropped from 46% to 10% while production costs fell by about 40?58%. In a number of communities, farmers formed groups after completing FFS training. These groups of FFS graduates met and discussed issues together. They also demonstrated IPM to other farmers who did not participate in a FFS. The results of these training activities convinced the relevant Government authorities at the time that the IPM/FFS had the potential to complement the extension delivery in the country. Thus, Government directed that it should be scaled up to cover other crops and made available to larger group of farmers. For this reason, a National workshop was held in Accra in December 1999, with the following objectives: Review the achievements of the IPM/FFS; Develop strategies for creating awareness within the relevant agencies and communities; and Examine the potential of the IPM/FFS training for overall agricultural and rural development in Ghana. A general observation made during the workshop was that, in view of the multidisciplinary nature of the subjects covered in the IPM/FFSs, it was felt more appropriate to adopt the name Integrated Crop and Pest Management Farmers? Field School (ICPM/FFS). Furthermore, taking note of the fact that the FFS was an extension methodology, the workshop recommended that the ICPM/FFS training methodology should be extended to cover other activities in the Ministry of Food and Agriculture including livestock. A policy framework was to be put in place to ensure that the establishment and implementation of the training methodology was harmonised with other agricultural extension activities. Subsequently, the ICPM/FFS was progressively applied to Ghana?s agriculture and there was a great input in training farmers in target districts of the UNDP/FAO?s funded National Poverty Reduction Programme (NPRP) in Ghana. By the end of the NPRP, well-established and tested guidelines for developing methodologies and curricula for FFS trainings had emerged. The following crops had been handled: rice, cassava, cowpea, plantain and vegetables. The number of extension agents including village worker NGOs trained as ICPM/FFS facilitators in Ghana came to two hundred, and two thousand four hundred farmers trained in healthy production of rice (1085), vegetables (824) and plantain (261). Two case studies about cabbage production at Weija Irrigation Scheme and Managing of plantain weevils and nematodes showed that with ICPM/FFS practices farmers were able to produce cabbage and plantain in a cost effective, highly profitable and environmentally sound manner with less use of pesticides. © 2015 Research Information Ltd. All rights reserved.Item Management of the Mediterranean fruit fly (Ceratitis Capitata Wied.) Using Pheromone Traps and Neem Seed Extract(University of Ghana, 1999-11) Akotsen-Mensah, C.; Afreh-Nuamah, K.; Ofori, D.O.; Ofosu-Budu, K.G.Laboratory and field experiments were conducted to evaluate the effectiveness of neem seed water extracts (NSWE) and pheromone traps to control the Mediterranean fruit fly, C capitata infesting citrus at the University of Ghana Agricultural Research Station (ARS), Kade. Neem seed extract of concentration 15%, 20%, 25% and 30% wt/vol were prepared and left overnight after which the suspensions were seived and used for spraying. Ripened fruits of Citrus sinensis cultivar Late Valencia and Citrus unshiu cultivar Satsuma were harvested into insect cages containing adult C. capitata after which they were sprayed with the neem seed water extract (NSWE) suspensions Second and third instar larvae and pupae were removed from untreated rotten fruits into petri dishes. These were exposed to the various suspensions as indicated above. Field experiments were conducted concurrently with the laboratory experiment to determine the seasonal abundance and activity pattern of C. capitata using pheromone traps baited with med-call, a Japanese formulated pheromone. To monitor the seasonal abundance of C. capitata two rectangular traps each baited with trimedlure (TML) were installed in Satsuma and Late Valencia citrus orchards. Data were collected every other day between 8:00 - 10:00 am. from September, 1997 to July, 1998. A similar method was used to investigate the diurnal activity and behaviour of C. capitata from 6:00 am. - 6:00 pm. To test the effectiveness of the NSWE under field conditions, field experiment were conducted in two selected citrus orchards i.e. Late Valencia and Satsuma. The two fields were each laid under the Randomised Complete Block Design (RCBD). NSWE of 25kg/ha suspension was sprayed on the trees. Two controls of picking of dropped infested fruits and no picking of dropped infested fruits were included. Dimethoate 40EC was also used as the basis for comparing the performance of the NSWE suspension. Results from laboratory work showed that oviposition of the adult female was significantly reduced when 20%, 25%, and 30% wt/vol NSWE were sprayed on each citrus variety. The anti-ovipositional effect of NSWE was dosage-dependent. The number of oviposition punctures on Late Valencia were significantly fewer than on Satsuma. The development period from eggs to adult in fruits sprayed with the NSWE suspensions was found to be between 38 - 40 days which was not significantly different among the citrus species examined. 25% and 30% wt/vol. of NSWE were more effective against the larvae removed from fruits. About 79% of 2nd instar larvae died when exposed to 25% and 30% NSWE suspensions. The percent mortalities were 73% and 84% for 25% and 30%wt/vol NSWE respectively when 3rd instar larvae were exposed. Furthermore, the development of pupae into adult was delayed by 6 — 9 days. There was significant difference among the treatments when pupae were sprayed together with soil. However there was no significant difference on the mortality of the pupae when only the soil was sprayed with the NSWE before introducing the untreated pupae. The results from the seasonal abundance and diurnal activity pattern using the pheromone traps indicated that, the population of C capitata was high during the period of fruit maturation (colour break) and continued till harvesting. The peak periods in Satsuma occurred in September 1997(38.5) and March 1998 (68.5) whereas that of Late Valencia occurred in December 1997 (36.5) and March 1998 (29.5) which are the harvesting periods for Satsuma and Late Valencia respectively. The diurnal activity of C. capitata was higher during 8:00- 10:00 am. than 3:00-5:00 pm . The mean number of 9.1 and 10.0 per trap were recorded between 8:00-10:00 am. for Late Valencia and Satsuma orchards respectively. The value for 3:00-5:00 pm. were 4.4 and S.l for Late Valencia and Satsuma respectively. The management practices adopted in the field to determine the effectiveness of NSWE under field conditions showed that C. capitata caused as high as 46% and 32% damage to Satsuma and Late Valencia citrus fruits respectively if not controlled. Damage was high in Trimedlure + picking of dropped infested fruits (TML+P) (46%) treated plots. The neem seed water extract and picking of dropped infested fruits (NSWE+P) treated plants performed significantly better than Control + no picking of infested dropped fruits (CNP), control + picking of infested dropped fruits (CP) and TML+P. Percentage damage recorded in the NSWE+P treated plots was however, significantly higher than the Dimethoate 40 EC and picking of dropped infested fruits (Dim+P) treated plots. Dim+P reduced fruits damage by more than half compared with the trimedlure and the control plots Dim+P and NSWE+P reduced the population of C. capitata by 27% and 10% the Satsuma orchards respectively. Similarly the C. capitata population was reduced by 24% and 14% by Dim+P in the Late Valencia orchard respectively. The NSWE sprayed at 25 kg/ha was comparatively better than the control treated plants. The cost-benefit analysis showed that the cost of spraying the NSWE could be beneficial particularly in the Satsuma orchard. This was however, not the case in the Late Valencia orchard. The relationship between adult C. capitata captured in TML baited traps, the number of damaged fruits, the number of larvae and pupae from damage fruits and the number of oviposition holes on fruits showed significant correlation.