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Zeyaur R. Khan - One of the best experts on this subject based on the ideXlab platform.
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Host range for Stemborers and associated natural enemies in different farming systems of Kenya
African Crop Science Journal, 2020Co-Authors: Fn Muyekho, At Barrion, Zeyaur R. KhanAbstract:The geographical distribution and grass host range for Stemborers and their natural enemies were assessed in three districts of Kenya between June 2002 and August 2003. In each district, grasses were sampled and dissected for presence of stem borers and/or their parasitoids (natural enemies). This was done in three cropping systems; (a) maize (Zea mays) surrounded by wild grasses, (b) sorghum (Sorghum bicolor) surrounded by wild grasses and (c) uncultivated grasslands. Busia and Suba districts had the higher diversity of Stemborers than Machakos district. Similarly, parasitoids diversity was highest in Busia (24), followed by Suba (19) and the least in Machakos (9). Thirty-four species of Stemborers belonging to the orders: Coleoptera [Anthribidae (1), Cerambycidae (3), Curculionidae (7), Mordellidae (3), Languriidae (3), and Tenebrionidae (2)]; and Lepidoptera [Noctuidae (6), Pyralidae (7), Cossidae (1), and Tortricidae (1)] were recovered from 31 grass species. Grass species that accounted for the highest diversity of Stemborers were Hyparrhenia (Hyparrhenia rufa), Barnyard grass (Echinochloa pyramidalis), Guine grass (Panicum maximum), Guinea-fowl grass (Rottboellia cochinchinensis) and wild sorghum (Sorghum versicolor), Lemon grass (Cymbopogon afronardus), Hyparrhenia (Hyparrhenia rufa), Guine grass (Panicum maximum) and sporobolus (Sporobolus pyramidalis) were grass species with the highest parasitoid diversity.
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a climate adapted push pull system effectively controls fall armyworm spodoptera frugiperda j e smith in maize in east africa
Crop Protection, 2018Co-Authors: Charles A. O. Midega, Girma Hailu, Jimmy Pittchar, J A Pickett, Zeyaur R. KhanAbstract:Fall armyworm, Spodoptera frugiperda (J E Smith), an economically important pest native to tropical and sub-tropical America has recently invaded Africa, causing substantial damage to maize and other crops. We evaluated functionality of a companion cropping system, ‘climate-adapted push-pull’, developed for control of cereal Stemborers in drier agro-ecologies, as an added tool for the management of fall armyworm. The technology comprises intercropping maize with drought-tolerant greenleaf desmodium, Desmodium intortum (Mill.) Urb., and planting Brachiaria cv Mulato II as a border crop around this intercrop. Protection to maize is provided by semiochemicals that are emitted by the intercrop that repel (push) Stemborer moths while those released by the border crop attract (pull) them. 250 farmers who had adopted the technology in drier areas of Kenya, Uganda and Tanzania were randomly selected for the study during the long rainy season (March-August) of 2017. Each farmer had a set of two plots, a climate-adapted push–pull and a maize monocrop. Data were collected in each plot on the number of fall armyworm larvae on maize, percentage of maize plants damaged by the larvae and maize grain yields. Similarly, farmers' perceptions of the impact of the technology on the pest were assessed using a semi-structured questionnaire. Reductions of 82.7% in average number of larvae per plant and 86.7% in plant damage per plot were observed in climate-adapted push-pull compared to maize monocrop plots. Similarly, maize grain yields were significantly higher, 2.7 times, in the climate-adapted push-pull plots. Farmers rated the technology significantly superior in reducing fall armyworm infestation and plant damage rates. These results demonstrate that the technology is effective in controlling fall armyworm with concomitant maize grain yield increases, and represent the first documentation of a technology that can be immediately deployed for management of the pest in East Africa and beyond.
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Responses of Parasitoids to Volatiles Induced by Chilo partellus Oviposition on Teosinte, a Wild Ancestor of Maize
Journal of Chemical Ecology, 2015Co-Authors: Daniel M. Mutyambai, John A. Pickett, Charles A. O. Midega, Toby J. A. Bruce, Christine M. Woodcock, Johnnie Van Den Berg, John C. Caulfield, Zeyaur R. KhanAbstract:Maize, a genetically diverse crop, is the domesticated descendent of its wild ancestor, teosinte. Recently, we have shown that certain maize landraces possess a valuable indirect defense trait not present in commercial hybrids. Plants of these landraces release herbivore-induced plant volatiles (HIPVs) that attract both egg [ Trichogramma bournieri Pintureau & Babault (Hymenoptera: Trichogrammatidae)] and larval [ Cotesia sesamiae Cameron (Hymenoptera: Braconidae)] parasitoids in response to Stemborer egg deposition. In this study, we tested whether this trait also exists in the germplasm of wild Zea species. Headspace samples were collected from plants exposed to egg deposition by Chilo partellus Swinhoe (Lepidoptera: Crambidae) moths and unexposed control plants. Four-arm olfactometer bioassays with parasitic wasps, T. bournieri and C. sesamiae , indicated that both egg and larval parasitoids preferred HIPVs from plants with eggs in four of the five teosinte species sampled. Headspace samples from oviposited plants released higher amounts of EAG-active compounds such as ( E )-4,8-dimethyl-1,3,7-nonatriene. In oviposition choice bioassays, plants without eggs were significantly preferred for subsequent oviposition by moths compared to plants with prior oviposition. These results suggest that this induced indirect defence trait is not limited to landraces but occurs in wild Zea species and appears to be an ancestral trait. Hence, these species possess a valuable trait that could be introgressed into domesticated maize lines to provide indirect defense mechanisms against Stemborers.
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effects of landscape complexity and habitat management on Stemborer colonization parasitism and damage to maize
Agriculture Ecosystems & Environment, 2014Co-Authors: Charles A. O. Midega, Zeyaur R. Khan, Mattias Jonsson, Barbara EkbomAbstract:Lepidopteran Stemborers are a serious constraint to efficient production of maize in sub-Saharan Africa. One of the most effective ways of managing these pests is through a habitat management system called push–pull. Landscape complexity has been shown to enhance biological control of insect pests, and therefore may influence effectiveness of habitat management systems designed to control pests. We studied the relative importance of the push–pull cropping system as a local effect and proportional cover of grassland as a landscape effect on (i) Stemborer population density and damage to maize, and (ii) parasitism and mortality of Stemborer life stages in western Kenya. We found a significant interactive effect between cropping system and grassland cover on abundance of Stemborer larvae and pupa, and a near significant interactive effect of these variables on rates of egg parasitism. Cropping system had the largest effect on larval and pupal abundance in more complex landscapes, whereas it affected egg parasitism most strongly in the simplest landscapes. Grasslands appeared to primarily function as a source for the pests, rather than for natural enemies. However, sites from landscapes with a larger range of grassland cover need to be studied to fully explore the combined effects of cropping system and landscape complexity on pest control in this system. The push–pull cropping system significantly suppressed Stemborer colonization of the maize and enhanced activity of Stemborer parasitoids, with significant reductions in crop damage and increase in grain yield.
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achieving food security for one million sub saharan african poor through push pull innovation by 2020
Philosophical Transactions of the Royal Society B, 2014Co-Authors: Zeyaur R. Khan, Charles A. O. Midega, Toby J. A. Bruce, Michael A. Birkett, Jimmy Pittchar, A W Murage, J A PickettAbstract:Food insecurity is a chronic problem in Africa and is likely to worsen with climate change and population growth. It is largely due to poor yields of the cereal crops caused by factors including Stemborer pests, striga weeds and degraded soils. A platform technology, ‘push–pull’, based on locally available companion plants, effectively addresses these constraints resulting in substantial grain yield increases. It involves intercropping cereal crops with a forage legume, desmodium, and planting Napier grass as a border crop. Desmodium repels Stemborer moths (push), and attracts their natural enemies, while Napier grass attracts them (pull). Desmodium is very effective in suppressing striga weed while improving soil fertility through nitrogen fixation and improved organic matter content. Both companion plants provide high-value animal fodder, facilitating milk production and diversifying farmers’ income sources. To extend these benefits to drier areas and ensure long-term sustainability of the technology in view of climate change, drought-tolerant trap and intercrop plants are being identified. Studies show that the locally commercial brachiaria cv mulato (trap crop) and greenleaf desmodium (intercrop) can tolerate long droughts. New on-farm field trials show that using these two companion crops in adapted push–pull technology provides effective control of Stemborers and striga weeds, resulting in significant grain yield increases. Effective multi-level partnerships have been established with national agricultural research and extension systems, non-governmental organizations and other stakeholders to enhance dissemination of the technology with a goal of reaching one million farm households in the region by 2020. These will be supported by an efficient desmodium seed production and distribution system in eastern Africa, relevant policies and stakeholder training and capacity development.
Charles A. O. Midega - One of the best experts on this subject based on the ideXlab platform.
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a climate adapted push pull system effectively controls fall armyworm spodoptera frugiperda j e smith in maize in east africa
Crop Protection, 2018Co-Authors: Charles A. O. Midega, Girma Hailu, Jimmy Pittchar, J A Pickett, Zeyaur R. KhanAbstract:Fall armyworm, Spodoptera frugiperda (J E Smith), an economically important pest native to tropical and sub-tropical America has recently invaded Africa, causing substantial damage to maize and other crops. We evaluated functionality of a companion cropping system, ‘climate-adapted push-pull’, developed for control of cereal Stemborers in drier agro-ecologies, as an added tool for the management of fall armyworm. The technology comprises intercropping maize with drought-tolerant greenleaf desmodium, Desmodium intortum (Mill.) Urb., and planting Brachiaria cv Mulato II as a border crop around this intercrop. Protection to maize is provided by semiochemicals that are emitted by the intercrop that repel (push) Stemborer moths while those released by the border crop attract (pull) them. 250 farmers who had adopted the technology in drier areas of Kenya, Uganda and Tanzania were randomly selected for the study during the long rainy season (March-August) of 2017. Each farmer had a set of two plots, a climate-adapted push–pull and a maize monocrop. Data were collected in each plot on the number of fall armyworm larvae on maize, percentage of maize plants damaged by the larvae and maize grain yields. Similarly, farmers' perceptions of the impact of the technology on the pest were assessed using a semi-structured questionnaire. Reductions of 82.7% in average number of larvae per plant and 86.7% in plant damage per plot were observed in climate-adapted push-pull compared to maize monocrop plots. Similarly, maize grain yields were significantly higher, 2.7 times, in the climate-adapted push-pull plots. Farmers rated the technology significantly superior in reducing fall armyworm infestation and plant damage rates. These results demonstrate that the technology is effective in controlling fall armyworm with concomitant maize grain yield increases, and represent the first documentation of a technology that can be immediately deployed for management of the pest in East Africa and beyond.
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Ecological management of cereal Stemborers in African smallholder agriculture through behavioural manipulation.
Ecological Entomology, 2015Co-Authors: Charles A. O. Midega, John A. Pickett, Toby J. A. Bruce, Z. R. KhanAbstract:1. Africa faces serious challenges in feeding its rapidly growing human population owing to the poor productivity of maize and sorghum, the most important staple crops for millions of smallholder farmers in the continent, with yields being among the lowest in the world. 2. A complex of lepidopterous Stemborers attack cereals in Africa. However, their effective control is difficult, largely as a result of the cryptic and nocturnal habits of moths, and protection provided by host stem for immature pest stages. Moreover, current control measures are uneconomical and impractical for resource-poor farmers. 3. An ecological approach, based on companion planting, known as ‘push–pull’, provides effective management of these pests, and involves combined use of inter- and trap cropping systems where Stemborers are attracted and trapped on trap plants with added economic value (‘pull’), and are driven away from the cereal crop by antagonistic intercrops (‘push’). 4. Novel defence strategies inducible by Stemborer oviposition have recently been discovered, leading to the attraction of egg and larval parasitoids, in locally adapted maize lines but not in elite hybrids. We also established that landscape complexity did not improve the ecosystem service of biological control, but rather provided a disservice by acting as a ‘source’ of Stemborer pests colonising the crop. 5. Here we review and provide new data on the direct and indirect effects of the push–pull approach on Stemborers and their natural enemies, including the mechanisms involved, and highlight opportunities for exploiting intrinsic plant defences and natural ecosystem services in pest management in smallholder farming systems in Africa.
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Responses of Parasitoids to Volatiles Induced by Chilo partellus Oviposition on Teosinte, a Wild Ancestor of Maize
Journal of Chemical Ecology, 2015Co-Authors: Daniel M. Mutyambai, John A. Pickett, Charles A. O. Midega, Toby J. A. Bruce, Christine M. Woodcock, Johnnie Van Den Berg, John C. Caulfield, Zeyaur R. KhanAbstract:Maize, a genetically diverse crop, is the domesticated descendent of its wild ancestor, teosinte. Recently, we have shown that certain maize landraces possess a valuable indirect defense trait not present in commercial hybrids. Plants of these landraces release herbivore-induced plant volatiles (HIPVs) that attract both egg [ Trichogramma bournieri Pintureau & Babault (Hymenoptera: Trichogrammatidae)] and larval [ Cotesia sesamiae Cameron (Hymenoptera: Braconidae)] parasitoids in response to Stemborer egg deposition. In this study, we tested whether this trait also exists in the germplasm of wild Zea species. Headspace samples were collected from plants exposed to egg deposition by Chilo partellus Swinhoe (Lepidoptera: Crambidae) moths and unexposed control plants. Four-arm olfactometer bioassays with parasitic wasps, T. bournieri and C. sesamiae , indicated that both egg and larval parasitoids preferred HIPVs from plants with eggs in four of the five teosinte species sampled. Headspace samples from oviposited plants released higher amounts of EAG-active compounds such as ( E )-4,8-dimethyl-1,3,7-nonatriene. In oviposition choice bioassays, plants without eggs were significantly preferred for subsequent oviposition by moths compared to plants with prior oviposition. These results suggest that this induced indirect defence trait is not limited to landraces but occurs in wild Zea species and appears to be an ancestral trait. Hence, these species possess a valuable trait that could be introgressed into domesticated maize lines to provide indirect defense mechanisms against Stemborers.
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effects of landscape complexity and habitat management on Stemborer colonization parasitism and damage to maize
Agriculture Ecosystems & Environment, 2014Co-Authors: Charles A. O. Midega, Zeyaur R. Khan, Mattias Jonsson, Barbara EkbomAbstract:Lepidopteran Stemborers are a serious constraint to efficient production of maize in sub-Saharan Africa. One of the most effective ways of managing these pests is through a habitat management system called push–pull. Landscape complexity has been shown to enhance biological control of insect pests, and therefore may influence effectiveness of habitat management systems designed to control pests. We studied the relative importance of the push–pull cropping system as a local effect and proportional cover of grassland as a landscape effect on (i) Stemborer population density and damage to maize, and (ii) parasitism and mortality of Stemborer life stages in western Kenya. We found a significant interactive effect between cropping system and grassland cover on abundance of Stemborer larvae and pupa, and a near significant interactive effect of these variables on rates of egg parasitism. Cropping system had the largest effect on larval and pupal abundance in more complex landscapes, whereas it affected egg parasitism most strongly in the simplest landscapes. Grasslands appeared to primarily function as a source for the pests, rather than for natural enemies. However, sites from landscapes with a larger range of grassland cover need to be studied to fully explore the combined effects of cropping system and landscape complexity on pest control in this system. The push–pull cropping system significantly suppressed Stemborer colonization of the maize and enhanced activity of Stemborer parasitoids, with significant reductions in crop damage and increase in grain yield.
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achieving food security for one million sub saharan african poor through push pull innovation by 2020
Philosophical Transactions of the Royal Society B, 2014Co-Authors: Zeyaur R. Khan, Charles A. O. Midega, Toby J. A. Bruce, Michael A. Birkett, Jimmy Pittchar, A W Murage, J A PickettAbstract:Food insecurity is a chronic problem in Africa and is likely to worsen with climate change and population growth. It is largely due to poor yields of the cereal crops caused by factors including Stemborer pests, striga weeds and degraded soils. A platform technology, ‘push–pull’, based on locally available companion plants, effectively addresses these constraints resulting in substantial grain yield increases. It involves intercropping cereal crops with a forage legume, desmodium, and planting Napier grass as a border crop. Desmodium repels Stemborer moths (push), and attracts their natural enemies, while Napier grass attracts them (pull). Desmodium is very effective in suppressing striga weed while improving soil fertility through nitrogen fixation and improved organic matter content. Both companion plants provide high-value animal fodder, facilitating milk production and diversifying farmers’ income sources. To extend these benefits to drier areas and ensure long-term sustainability of the technology in view of climate change, drought-tolerant trap and intercrop plants are being identified. Studies show that the locally commercial brachiaria cv mulato (trap crop) and greenleaf desmodium (intercrop) can tolerate long droughts. New on-farm field trials show that using these two companion crops in adapted push–pull technology provides effective control of Stemborers and striga weeds, resulting in significant grain yield increases. Effective multi-level partnerships have been established with national agricultural research and extension systems, non-governmental organizations and other stakeholders to enhance dissemination of the technology with a goal of reaching one million farm households in the region by 2020. These will be supported by an efficient desmodium seed production and distribution system in eastern Africa, relevant policies and stakeholder training and capacity development.
William A Overholt - One of the best experts on this subject based on the ideXlab platform.
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Control of Lepidopteran Stemborers in Maize by Indigenous Parasitoids in Semi-Arid Areas of Eastern Kenya
Biological Agriculture & Horticulture, 2020Co-Authors: Josephine M Songa, William A Overholt, R. O. Okello, J. M. MuekeAbstract:ABSTRACT Stemborers of maize and their associated indigenous parasitoids were studied at Katumani, Kiboko and Ithookwe in the semi-arid areas of eastern Kenya over a period of four seasons (short rains, 1996—long rains, 1998). Maize fields established at each site were sampled at least weekly up to plant maturity, and all the Stemborer life stages recovered were reared individually in the laboratory for possible parasitoid emergence. The Stemborers that attacked maize at the three sites were Chilo partellus, the dominant and most widespread Stemborer, Sesamia calamistis, Cryptophlebia leucotretci and Busseola fusca. A complex of 22 mainly larval parasitoids attacked the Stemborers, but the parasitism was generally low. C. partellus was the most frequently parasitized Stemborer. The most widespread larval parasitoid was Cotesia sesamiae, followed by Chelonus curvimaculatus, while Dentichasmias busseolae and Pediobius furvus were the most common pupal parasitoids. The low percentage parasitism by indigenous...
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Farmers' perceptions of aspects of maize production systems and pests in semi-arid eastern Kenya: Factors influencing occurrence and control of Stemborers
International Journal of Pest Management, 2020Co-Authors: Josephine M Songa, William A Overholt, J. M. Mueke, R. O. OkelloAbstract:A farmer survey was conducted in six agro-ecological zones (AEZs) in semi-arid eastern Kenya to verify the socio-economic importance of maize, identify its pests and farmers' perceptions of the relative importance of the pests. We also determined some agronomic practices that may influence Stemborer infestation and identified the Stemborer control methods used. Pests reported included chafer grubs, Stemborers, termites, 'red ants', yellow-necked spur fowls, squirrels, monkeys, porcupines, rats, wild pigs and storage insect pests. Their relative importance in each AEZ is discussed. The squirrel was the most widely distributed and important vertebrate pest of maize in the study AEZs. Stemborers infested maize in all the zones, and ranked first among insect pests in the Upper Midland zone 4 (UM4), Lower Midland zone 3 (LM3) and LM4, and second in LM5, but were unimportant in UM2. Agronomic practices that may influence Stemborer infestation in maize, including cropping system, sowing time, fertilizer/manure u...
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Host–parasitoid community model and its potential application in biological control of cereal Stemborers in Kenya
Population Ecology, 2008Co-Authors: Nanqing Jiang, William A Overholt, Goufa Zhou, Fritz SchulthessAbstract:A two-host–two-parasitoid model was constructed to assess the effects of the introduced larval parasitoid, the braconid Cotesia flavipes, on its primary target host, the invasive crambid Chilo partellus, and on secondary host species, in inter-specific competition with Cotesia sesamiae, the main native parasitoid species of Stemborers in Kenya. The model assumed that: (1) there was no host discrimination by either parasitoid species; (2) Cotesia flavipes was the superior competitor that out-competed Cotesia sesamiae when the host was suitable; and (3) Cotesia flavipes could only develop in an unsuitable host if it had been previously parasitized by Cotesia sesamiae. Model parameters were estimated from surveys conducted in Kenya and from laboratory experiments. Different scenarios of host and parasitoid species composition and host suitability occurring in the different ecological zones in Kenya were analyzed. Results indicated that: (1) the coexistence of Stemborer host populations are determined by their population growth rates, the degree of aggregation of the parasitoids and their searching efficiency; (2) in the regions where both the invasive and the predominant native host species were suitable to either parasitoid species, Stemborer densities would be reduced to and controlled at low densities, and Cotesia flavipes would become the dominant parasitoid species. However, the extinction or predominance of the native Stemborer species depends on the ratio of the growth rates of exotic and native Stemborers and their relative searching efficiencies; and (3) if the native host species was acceptable but unsuitable to Cotesia flavipes, the parasite would not become established.
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the temporal correlation and spatial synchrony in the Stemborer and parasitoid system of coast kenya with climate effects
Annales De La Societe Entomologique De France, 2006Co-Authors: Nanqing Jiang, William A Overholt, Guofa Zhou, Eric Muchugu, F SchulthessAbstract:Abstract The spatial synchrony and the temporal auto-correlationship of the exotic Stemborer Chilo partellus (Swinhoe) (Lepidoptera: Crambidae) and the indigenous Sesamia calamistis Hampson (Lepidoptera: Noctuidae) and Chilo orichalcociliellus (Strand) (Lepidoptera: Crambidae), and crosscorrelationship with their indigenous and introduced larval parasitoids Cotesia sesamiae (Cameron) and Cotesia flavipes Cameron (Hymenoptera: Braconidae) was studied using 3-year data collected in coastal Kenya. An autoregressive model was used to study the effect of climatic stochasticity or population density-dependent factors on Stemborer populations. It appeared that rainfall did have a direct impact on Stemborers in the south coast and an indirect one in the north coast. Spatial nonparametric correlation functions (SNCF) and cross-correlation functions (SNCCF) were applied for spatial synchrony analysis. The regional synchrony of Ch. partellus and S. calamistis decreased and that of Ch. orichalcociliellus increased af...
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acceptance and suitability of four lepidopteran Stemborers for the development of the pupal parasitoid xanthopimpla stemmator hymenoptera ichneumonidae
Biocontrol Science and Technology, 2005Co-Authors: C W Gitau, William A Overholt, Adele J Ngisong, S A OtienoAbstract:Abstract Xanthopimpla stemmator (Thunberg), a solitary endoparasitoid of lepidopteran Stemborer pupae, was recently imported into East Africa as a candidate biological control agent of gramineous Stemborers. Suitability of Busseola fusca Fuller, Chilo partellus (Swinhoe), Eldana saccharina (Walker) and Sesamia calamistis Hampson, for the development of X. stemmator was studied in the laboratory. One- to 6-day-old laboratory reared pupae of the four Stemborer species were exposed to naive X. stemmator females. All host pupae and ages were acceptable for oviposition. The parasitoids inflicted multiple probe wounds on 67.8% of pupae exposed. B. fusca, C. partellus and S. calamistis were equally suitable with 56.4, 59.4 and 52.3%, respectively, of probed pupae leading to emergence of adult parasitoids. E. saccharina was less suitable with only 22.6% of probed pupae producing parasitoids. Emergence of parasitoids did not differ significantly across the six pupal ages for B. fusca and S. calamistis, but varied ...
John A. Pickett - One of the best experts on this subject based on the ideXlab platform.
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Ecological management of cereal Stemborers in African smallholder agriculture through behavioural manipulation.
Ecological Entomology, 2015Co-Authors: Charles A. O. Midega, John A. Pickett, Toby J. A. Bruce, Z. R. KhanAbstract:1. Africa faces serious challenges in feeding its rapidly growing human population owing to the poor productivity of maize and sorghum, the most important staple crops for millions of smallholder farmers in the continent, with yields being among the lowest in the world. 2. A complex of lepidopterous Stemborers attack cereals in Africa. However, their effective control is difficult, largely as a result of the cryptic and nocturnal habits of moths, and protection provided by host stem for immature pest stages. Moreover, current control measures are uneconomical and impractical for resource-poor farmers. 3. An ecological approach, based on companion planting, known as ‘push–pull’, provides effective management of these pests, and involves combined use of inter- and trap cropping systems where Stemborers are attracted and trapped on trap plants with added economic value (‘pull’), and are driven away from the cereal crop by antagonistic intercrops (‘push’). 4. Novel defence strategies inducible by Stemborer oviposition have recently been discovered, leading to the attraction of egg and larval parasitoids, in locally adapted maize lines but not in elite hybrids. We also established that landscape complexity did not improve the ecosystem service of biological control, but rather provided a disservice by acting as a ‘source’ of Stemborer pests colonising the crop. 5. Here we review and provide new data on the direct and indirect effects of the push–pull approach on Stemborers and their natural enemies, including the mechanisms involved, and highlight opportunities for exploiting intrinsic plant defences and natural ecosystem services in pest management in smallholder farming systems in Africa.
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Responses of Parasitoids to Volatiles Induced by Chilo partellus Oviposition on Teosinte, a Wild Ancestor of Maize
Journal of Chemical Ecology, 2015Co-Authors: Daniel M. Mutyambai, John A. Pickett, Charles A. O. Midega, Toby J. A. Bruce, Christine M. Woodcock, Johnnie Van Den Berg, John C. Caulfield, Zeyaur R. KhanAbstract:Maize, a genetically diverse crop, is the domesticated descendent of its wild ancestor, teosinte. Recently, we have shown that certain maize landraces possess a valuable indirect defense trait not present in commercial hybrids. Plants of these landraces release herbivore-induced plant volatiles (HIPVs) that attract both egg [ Trichogramma bournieri Pintureau & Babault (Hymenoptera: Trichogrammatidae)] and larval [ Cotesia sesamiae Cameron (Hymenoptera: Braconidae)] parasitoids in response to Stemborer egg deposition. In this study, we tested whether this trait also exists in the germplasm of wild Zea species. Headspace samples were collected from plants exposed to egg deposition by Chilo partellus Swinhoe (Lepidoptera: Crambidae) moths and unexposed control plants. Four-arm olfactometer bioassays with parasitic wasps, T. bournieri and C. sesamiae , indicated that both egg and larval parasitoids preferred HIPVs from plants with eggs in four of the five teosinte species sampled. Headspace samples from oviposited plants released higher amounts of EAG-active compounds such as ( E )-4,8-dimethyl-1,3,7-nonatriene. In oviposition choice bioassays, plants without eggs were significantly preferred for subsequent oviposition by moths compared to plants with prior oviposition. These results suggest that this induced indirect defence trait is not limited to landraces but occurs in wild Zea species and appears to be an ancestral trait. Hence, these species possess a valuable trait that could be introgressed into domesticated maize lines to provide indirect defense mechanisms against Stemborers.
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Oviposition Induced Volatile Emissions from African Smallholder Farmers’ Maize Varieties
Journal of Chemical Ecology, 2012Co-Authors: Amanuel Tamiru, John A. Pickett, Charles A. O. Midega, Toby J. A. Bruce, Christine M. Woodcock, Michael A. Birkett, Zeyaur R. KhanAbstract:Maize (corn), Zea mays , is a genetically diverse crop, and we have recently shown that certain open pollinated varieties (OPVs) of Latin American origin possess a trait not present in mainstream commercial varieties: they produce volatiles in response to Stemborer oviposition that are attractive to Stemborer parasitoids. Here, we tested whether a similar tritrophic effect occurs in the African OPVs ‘Nyamula’ and ‘Jowi’. Herbivore induced plant volatiles (HIPVs) were collected from plants exposed to egg deposition by the Stemborer Chilo partellus . In a four-arm olfactometer bioassay, the parasitic wasp Cotesia sesamiae preferred samples containing HIPVs from plants with eggs to samples collected from plants without eggs. EAG-active compounds, including ( E )-4,8-dimethyl-1,3,7-nonatriene (DMNT), were released in higher amounts from the egg induced headspace samples. Our results suggest that this oviposition trait is not limited to S. American Z. mays germplasm, and that it could be used to increase indirect defense against attack by Stemborers.
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Farmers’ perceptions of a ‘push–pull’ technology for control of cereal Stemborers and Striga weed in western Kenya
Crop Protection, 2008Co-Authors: Zeyaur R. Khan, Charles A. O. Midega, David M. Amudavi, Japhether M. Wanyama, John A. PickettAbstract:Abstract Striga and cereal Stemborers are major constraints to cereal production in sub-Saharan Africa causing serious food security concerns. The International Centre of Insect Physiology and Ecology (ICIPE) and partners have developed a novel integrated management system called the ‘push–pull’ technology (PPT) in mitigation. This involves inter-cropping maize with a Stemborer moth-repellent forage legume, silverleaf desmodium (push), and planting an attractive trap crop, Napier grass (pull), around the intercrop. Additionally, chemicals produced from desmodium roots inhibit Striga . We evaluated farmers’ perceptions of the pests, PPT attributes and factors influencing the likelihood of its adoption in 15 districts in western Kenya. A random sample of 923 farmers, with 478 having adopted the technology (practicing) and 445 not yet adopted but attending PPT field days (visiting) were interviewed. The practicing farmers cited both Striga and Stemborers as major maize production constraints, alongside other constraints, as the main motivations for adoption of PPT. Reduced infestation by the pests, improvement in soil fertility, increase in maize grain yields, improved fodder and milk productivity were cited as main benefits of PPT. Similarly, the field day visiting farmers rated PPT as a more superior technology compared to their own maize production practices. Farmer's age, household headship by female farmers, technology attributes and exposure to a variety of extension methods significantly influenced likelihood of PPT adoption. Effective dissemination pathways are needed to provide farmers with appropriate information for evaluating potential benefits and tradeoffs of such a management-intensive technology. Further research is needed to understand how PPT contributes to farmers’ livelihood improvement and how the efficacy of different dissemination pathways in PPT technology transfer influences its adoption.
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On-farm evaluation of the 'push-pull' technology for the control of Stemborers and striga weed on maize in western Kenya
Field Crops Research, 2008Co-Authors: Zeyaur R. Khan, Ahmed Hassanali, Charles A. O. Midega, David M. Amudavi, John A. PickettAbstract:Abstract The ‘push–pull’ technology is a novel pest management strategy developed for control of Stemborers and striga weed, Striga hermonthica , in maize-based farming systems in eastern Africa, where maize is intercropped with desmodium, a forage legume, and Napier grass is planted as a border crop. Desmodium repels Stemborer moths while Napier grass attracts them. Desmodium also suppresses the parasitic striga weed through a series of mechanisms ranging from shading to allelopathy through the root system. The technology is currently being disseminated among smallholder farmers in eastern Africa and adoption rates are rising. Our on-station studies have reported efficacy of this technology against the two pests resulting in increased grain yields. The current study was conducted between 2003 and 2006 in 14 districts in western Kenya to assess effectiveness of the technology under farmers’ own conditions. Twenty farmers from each district, who had adopted the technology, were randomly selected for the study. Each farmer had a set of two plots, a ‘push–pull’ and a maize monocrop. Seasonal data were collected on percentage of maize plants damaged by Stemborers, the number of emerged striga, plant height and grain yields. Similarly, farmers’ perceptions on the benefits of the technology were assessed using a structured questionnaire. Stemborer damage and striga counts to maize plants were significantly lower in the ‘push–pull’ plots than in the maize monocrop plots. Similarly, maize plant height and grain yields were significantly higher in the former. Farmers rated the ‘push–pull’ technology significantly superior in having reduced Stemborers and striga infestation rates and increased soil fertility and grain yields. These results demonstrate that the technology is equally effective in controlling both pests with concomitant yield increases under farmers’ conditions in the districts studied.
J A Pickett - One of the best experts on this subject based on the ideXlab platform.
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a climate adapted push pull system effectively controls fall armyworm spodoptera frugiperda j e smith in maize in east africa
Crop Protection, 2018Co-Authors: Charles A. O. Midega, Girma Hailu, Jimmy Pittchar, J A Pickett, Zeyaur R. KhanAbstract:Fall armyworm, Spodoptera frugiperda (J E Smith), an economically important pest native to tropical and sub-tropical America has recently invaded Africa, causing substantial damage to maize and other crops. We evaluated functionality of a companion cropping system, ‘climate-adapted push-pull’, developed for control of cereal Stemborers in drier agro-ecologies, as an added tool for the management of fall armyworm. The technology comprises intercropping maize with drought-tolerant greenleaf desmodium, Desmodium intortum (Mill.) Urb., and planting Brachiaria cv Mulato II as a border crop around this intercrop. Protection to maize is provided by semiochemicals that are emitted by the intercrop that repel (push) Stemborer moths while those released by the border crop attract (pull) them. 250 farmers who had adopted the technology in drier areas of Kenya, Uganda and Tanzania were randomly selected for the study during the long rainy season (March-August) of 2017. Each farmer had a set of two plots, a climate-adapted push–pull and a maize monocrop. Data were collected in each plot on the number of fall armyworm larvae on maize, percentage of maize plants damaged by the larvae and maize grain yields. Similarly, farmers' perceptions of the impact of the technology on the pest were assessed using a semi-structured questionnaire. Reductions of 82.7% in average number of larvae per plant and 86.7% in plant damage per plot were observed in climate-adapted push-pull compared to maize monocrop plots. Similarly, maize grain yields were significantly higher, 2.7 times, in the climate-adapted push-pull plots. Farmers rated the technology significantly superior in reducing fall armyworm infestation and plant damage rates. These results demonstrate that the technology is effective in controlling fall armyworm with concomitant maize grain yield increases, and represent the first documentation of a technology that can be immediately deployed for management of the pest in East Africa and beyond.
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achieving food security for one million sub saharan african poor through push pull innovation by 2020
Philosophical Transactions of the Royal Society B, 2014Co-Authors: Zeyaur R. Khan, Charles A. O. Midega, Toby J. A. Bruce, Michael A. Birkett, Jimmy Pittchar, A W Murage, J A PickettAbstract:Food insecurity is a chronic problem in Africa and is likely to worsen with climate change and population growth. It is largely due to poor yields of the cereal crops caused by factors including Stemborer pests, striga weeds and degraded soils. A platform technology, ‘push–pull’, based on locally available companion plants, effectively addresses these constraints resulting in substantial grain yield increases. It involves intercropping cereal crops with a forage legume, desmodium, and planting Napier grass as a border crop. Desmodium repels Stemborer moths (push), and attracts their natural enemies, while Napier grass attracts them (pull). Desmodium is very effective in suppressing striga weed while improving soil fertility through nitrogen fixation and improved organic matter content. Both companion plants provide high-value animal fodder, facilitating milk production and diversifying farmers’ income sources. To extend these benefits to drier areas and ensure long-term sustainability of the technology in view of climate change, drought-tolerant trap and intercrop plants are being identified. Studies show that the locally commercial brachiaria cv mulato (trap crop) and greenleaf desmodium (intercrop) can tolerate long droughts. New on-farm field trials show that using these two companion crops in adapted push–pull technology provides effective control of Stemborers and striga weeds, resulting in significant grain yield increases. Effective multi-level partnerships have been established with national agricultural research and extension systems, non-governmental organizations and other stakeholders to enhance dissemination of the technology with a goal of reaching one million farm households in the region by 2020. These will be supported by an efficient desmodium seed production and distribution system in eastern Africa, relevant policies and stakeholder training and capacity development.
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integrated management of striga hermonthica and cereal Stemborers in finger millet eleusine coracana l gaertn through intercropping with desmodium intortum
International Journal of Pest Management, 2010Co-Authors: Charles A. O. Midega, Zeyaur R. Khan, David M. Amudavi, Jimmy Pittchar, J A PickettAbstract:We evaluated the potential role of greenleaf desmodium, Desmodium intortum (Mill.) Urb., in the combined management of Striga hermonthica and cereal Stemborers in finger millet (Eleusine coracana (L.) Gaertn.) in western Kenya between 2007 and 2008. Treatments comprised finger millet planted either as monocrop stands or intercropped with D. intortum. S. hermonthica counts were significantly lower in the intercrop than in the monocrop plots. Similarly, multi-season analyses showed that the proportions of Stemborer-damaged plants were significantly lower in the intercrop than in the monocrop. These differences were associated with significantly higher grain yields in the intercrop than in the monocrop. Total labour and variable costs were significantly higher in the intercrop resulting from the additional seed cost and labour to plant, manage and harvest D. intortum. However, total revenue and gross margins were significantly higher in the intercrop due to the higher finger millet grain yields and additiona...
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integration of edible beans phaseolus vulgaris l into the push pull technology developed for Stemborer and striga control in maize based cropping systems
Crop Protection, 2009Co-Authors: Zeyaur R. Khan, Ahmed Hassanali, Charles A. O. Midega, David M. Amudavi, Jimmy Pittchar, Japhether M. Wanyama, J A PickettAbstract:Smallholder farming systems in eastern Africa are characterized by cereal/edible legume intercrops in fields severely constrained by parasitic weed, Striga hermonthica, cereal Stemborers and declining soil fertility. The push–pull technology concurrently addresses these constraints. It involves intercropping maize with Stemborer repellent fodder legume, Desmodium spp. (push), with an attractant crop, Napier grass, Pennisetum purpureum (pull), planted around this intercrop, thus making it difficult to interplant edible legumes. We assessed farmers’ practice and perceptions on intercropping and willingness to integrate beans in their push–pull plots from a sample of 300 farmers in six districts in western Kenya. All the respondents traditionally intercropped maize with beans, planted either between the rows of maize, in the same holes with maize or in between maize plants within a row. The majority (92%) were willing to integrate beans in their push–pull plots. We, therefore, evaluated effects of integrating beans in the maize–desmodium intercrops. Treatments comprised a maize monocrop, maize–bean intercrop and three maize–desmodium intercrops, two of which were integrated with beans, either in the same holes with maize or in between maize plants in a row (bean integration plots). On-farm trials were similarly established among 56 farmers in four districts in western Kenya to assess the two integration methods. S. hermonthica counts and Stemborer damage to maize were significantly lower and maize yields significantly higher in the maize–desmodium and bean integration plots than in the other systems. Overall, integration of beans in the maize–desmodium intercrops and the planting arrangement did not compromise the S. hermonthica and Stemborer control efficacy of desmodium. Integration of beans significantly increased labour and total variable costs, with these being significantly higher in plots with both crops in different holes than in the same hole. Total revenue, gross benefits and benefit cost ratios did not significantly differ between the bean integration and maize–desmodium intercrops. Furthermore, these parameters were for most part not affected by the planting arrangements, both on-station and on-farm. These results show that integration of beans in the maize–desmodium and indeed push– pull technology while guaranteeing an additional crop, a protein source, to the farmers does not compromise the observed benefits of the technology but yields same economic benefits. Where labour is easily available, farmers are, however, advised to plant maize and beans in separate holes to avoid the risk of competition for moisture and nutrients where these might be limiting.
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economic performance of the push pull technology for Stemborer and striga control in smallholder farming systems in western kenya
Crop Protection, 2008Co-Authors: Zeyaur R. Khan, Charles A. O. Midega, David M. Amudavi, Japhether M. Wanyama, Esther M Njuguna, J A PickettAbstract:Abstract The ‘push–pull’ technology (PPT), developed in Africa, offers effective control of cereal Stemborers and Striga weed in maize-based cropping systems. It involves intercropping maize with desmodium, Desmodium uncinatum, with Napier grass, Pennisetum purpureum, planted as border around this intercrop. Desmodium repels the Stemborer moths (push) that are subsequently attracted to the Napier grass (pull). Desmodium also suppresses and eliminates Striga. We assessed economic performance of this technology compared to the conventional maize mono- and maize–bean intercropping systems in six districts in western Kenya over 4–7 years. Ten farmers were randomly recruited in each district and each planted three plots representing the three cropping systems. The cost–benefit analyses were carried out, together with the systems’ net returns to land and labour and their discounted net present values (NPV). Maize grain yields and associated gross margins from the PPT system were significantly higher than those in the other two systems. Although the production costs were significantly higher in the PPT than in the two cropping systems in the first cropping year, these reduced to either the same level or significantly lower than in the maize–bean intercrop from the second year onwards in most of the districts. Similarly, the net returns to land and labour with the PPT were significantly higher than with the other two systems. The PPT consistently produced positive NPV when the incremental flows of its benefits compared to those of the two conventional systems were discounted at 10–30%, indicating that PPT is more profitable than the other two systems under realistic production assumptions. PPT is thus a viable option for enhancing productivity and diversification for smallholder farmers who largely depend on limited land resource. Hence, enhancing farmers’ access to less costly planting materials and promoting quality education and training in the use of this knowledge-intensive technology could stimulate its successful adoption.
