Charles A O Midega

icipe – International Centre of Insect Physiology and Ecology | ICIPE · Plant Health Division

Intercropping is drawing increasing attention as a strategy to increase crop yields and manage pest pressure, however the mechanisms of associational resistance in diversified cropping systems remain controversial. We conducted a controlled experiment to assess the impact of co-planting with silverleaf Desmodium (Desmodium uncinatum) on maize secon...

Intercropping is drawing increasing attention as a strategy to increase crop yields and manage pest pressure; however the mechanisms of associational resistance remain controversial. We conducted a controlled experiment to assess the impact of co-planting with silverleaf Desmodium ( Desmodium uncinatum ) on maize secondary metabolism and resistance...

Introduction: Several Desmodium spp. are used as intercrops in push-pull pest management systems to repel insect herbivores. In addition, Desmodium suppresses the parasitic weed Striga, and diversifies the soil microbiome with negative impacts on fungi. We investigated the impact of a 2-year cropping of five Desmodium species on soil microbiome pop...

Farmers looking to maximize ecosystem services often use diversification practices on their fields to increase abundance and diversity of insect natural enemies. These practices affect functional traits of natural enemies such as body size that can play an important role in their effectiveness as biological control agents. However, landscape featur...

In order to meet the increasing demands from an exploding human population, sustainable agriculture relies on the availability of crop varieties with high yields and optimal defenses to pests. However, ample work has suggested that domesticated plants could have reduced defenses at the expense of increased biomass or yield, and these potential trad...

Application of biotechnology in the crop sector in sub-Saharan African countries was considered based on both the extent (e.g. limited use in laboratories versus widespread field use) and context (e.g. cloning individual genes versus cloning a whole organism) of use. Biotechnology types were allocated to three groups—low-, medium- and high-tech—dep...

Production of cereal crops in sub-Saharan Africa is threatened by parasitic striga weeds and attack by stemborers and the invasive fall armyworm (FAW), compounded by increasing hot and dry conditions. A climate-smart push-pull technology (PPT) significantly reduces effects of these biotic challenges. To improve further resilience of the system to c...

Push‐pull involves intercropping of cereals with Desmodium as a ‘push’ crop and planting Napier grass/Brachiaria as the ‘pull’ crop at the border. The technology has been reported to effectively control stemborers, striga weed and fall armyworm (FAW), and to improve soil nutrition resulting in increased grain yield. This study evaluated the impact...

The entire process of agricultural and horticultural food production is unsustainable as practiced by current highly intensive industrial systems. Energy consumption is particularly intensive for cultivation, and for fertilizer production and its incorporation into soil. Provision of nitrogen contributes a major source of the greenhouse gas, N2O. A...

Plants can alter nutritional availability, structure, and chemistry of the soil they grow in. These soil changes can positively or negatively influence the growth and metabolism of other plants that co-occur or grow later in the conditioned soil. Plant-soil feedbacks could affect community interactions and dynamics but also be applied in sustainabl...

Fall armyworm (FAW), a voracious agricultural pest native to North and South America, was first detected on the African continent in 2016 and has subsequently spread throughout the continent and across Asia. It has been predicted that FAW could cause up to $US13 billion per annum in crop losses throughout sub-Saharan Africa, thereby threatening the...

Push-pull, a novel approach for integrated management of insect pests, weed and soil fertility, was developed through the exploitation of chemical ecology and agro-biodiversity to address agricultural constraints facing millions of resource-poor African farmers. The technology was developed by selecting appropriate plants that naturally emit signal...

Stemborer pests contribute to significant maize crop yield loses incurred by the smallholder famers in Ethiopia. The problem requires requires concerted effort to learn and adopt new innovations to find a long lasting solution. In this study, the on-farm implementation of the push-pull technology (PPT) was used as a platform for interaction and enh...

Fall armyworm (FAW) Spodoptera frugiperda invaded Africa, with the first detections being reported in Central and Western Africa in early 2016, and now affects at least 40 countries in Africa, causing up to total crop loss amounting to over $6.2 billion p.a. FAW is an invasive polyphagous pest that causes damage to economically important crops and...

Grasses in the genus Urochloa, commonly known as brachiaria, are grown as forage crops in sub-Saharan Africa, with some genotypes being used in management of insect pests. However, spider mite, Oligonychus trichardti Meyer (Acari: Tetranychidae), has recently been reported as its major pest in the region. We evaluated 18 brachiaria genotypes to ide...

A transdisciplinary research approach requires that different scientists with their discipline-specific theories, concepts and methods find ways to work together with other societal players to address a real-life problem. In this study, the push–pull technology (PPT) was used as a boundary object to enable interactions among stakeholders across sci...

This study examines the farm-level economic benefits and aggregate welfare impacts of adopting push–pull technology (PPT)—an innovative, integrated pest and soil-fertility management strategy—with a set of household- and plot-level data collected in western Kenya. The evaluation is based on a combination of econometric and economic surplus analysis...

The cereal stemborer Chilo partellus (Swinhoe) (Lepidoptera: Crambidae) is a major insect pest of sorghum (Sorghum bicolor L. Moench) and maize (Zea mays L.) in Africa. Trap cropping systems have been shown to be a valuable tool in management of this pest. To optimize trap cropping strategies, an understanding of host-plant preference for moth ovip...

For sustainable production of Napier grass (Pennisetum purpureum), screening for the absence of phytoplasma on propagation material (stem) is carried by Nested-PCR in detection of 16S rDNA on leaves. However, the aim of this study was to investigate if there is uneven distribution of the pathogen in roots, stems and leaves of the infected plants th...

The Central region of Kenya which is the second largest market oriented dairy zone, faces a threat in milk production. The challenge is a disease known as the napier head smut caused by Ustilago kamerunensis. This fungal microorganism is a facultative pathogen which has been reported to cause yield losses in napier grass (Pennisetum purpureum) rang...

Napier grass stunt (NGS) disease is a major threat to Napier grass cultivation and the smallholder dairy industry in East and Central Africa. The disease is caused by a phytoplasma, which is transmitted by the leafhopper Maiestas banda (Kramer) (Hemiptera: Cicadellidae). The current study was conducted to identify among 65 Napier grass accessions t...

Maize (Zea mays) emits volatile terpenes in response to insect feeding and egg deposition to defend itself against harmful pests. However, maize cultivars differ strongly in their ability to produce the defense signal. To further understand the agroecological role and underlying genetic mechanisms for variation in terpene emission among maize culti...

This book provides an updated assessment of trends in the adaptation and adoption of conservation agriculture (CA) in different countries of Africa. It provides information on the contribution of CA systems to building resilience in a changing climate while increasing productivity, profitability and ecological sustainability. The book covers: the s...

Insect pests are a key constraint to effective utilization of cereal crops in sub-Saharan Africa (SSA), with damage caused by these pests in the stores of particular concern. Although a number of approaches have been advanced for control of storage pests of maize, uptake remains a challenge, with effectiveness of some approaches being questionable....

Attack of plants by herbivorous arthropods may result in considerable changes to the plant's chemical phenotype with respect to emission of herbivore-induced plant volatiles (HIPVs). These HIPVs have been shown to act as repellents to the attacking insects as well as attractants for the insects antagonistic to these herbivores. Plants can also resp...

Tables A, B and C. (XLS)

Lepidopterous stemborers, and parasitic striga weeds belonging to the family Orobanchaceae, attack cereal crops in sub-Saharan Africa causing severe yield losses. The smallholder farmers are resource constrained and unable to afford expensive chemicals for crop protection. The push–pull technology, a chemical ecology- based cropping system, is deve...

Production of Napier grass, Pennisetum purpureum, the most important forage crop in Africa, is severely constrained by Napier grass stunt (NGS) disease. Wild grasses have been identified as alternative hosts for NGS, but there is no record regarding the ability of this phytoplasma to infect cultivated food crops. To assess this threat, six crop spe...

The rice C-glycosyltransferase (OsCGT) is one of only a small number of characterised plant C-glycosyltransferases (CGT) known. The enzyme C-glucosylates a 2-hydroxyflavanone substrate with UDP-glucose as the sugar donor to produce C-glucosyl-2-hydroxyflavanones. We tested substrate specificity of the enzyme, using synthetic 2-hydroxyflavanones, an...

Plant-pathogenic phytoplasmas found in wild grasses in East Africa could pose a serious threat to the cultivation of Napier grass, Pennisetum purpureum, the most important livestock fodder in the region. To asses this threat, leaves from plants of 33 grass species were sampled from Mbita, Bungoma, and Busia districts in western Kenya; Tarime distri...

The performance of the agricultural sector in many developing countries has been rated as below average, in particular the staple cereal crops whose productivity is limited by both biotic and abiotic factors. Furthermore, underperformance by the agricultural sector has in part been attributed to the inability of women to access resources, yet they...

Species of the genus Brachiaria originate primarily from Africa, where they are constituents of natural grasslands. Due to their adaptation to acidic, low-fertility soils, millions of hectares of Brachiaria species have been sown as improved pastures in South and Central America, especially B. brizantha cv. Marandu and B. decumbens cv. Basilisk. Du...

Plants from the genus Desmodium, in particular D. uncinatum, are used on sub-Saharan small-holder farms as intercrops to inhibit parasitism of cereal crops by Striga hermonthica and Striga asiatica via an allelopathic mechanism. The search for Desmodium species which are adapted to more arid conditions, and which show resilience to increased drough...

Food security attainment in Africa has been hindered by poor yields of cereals that serve both as staple and cash crops for the majority of smallholder farmers. Among the various constraints responsible for lower yields are the parasitic weed Striga, and Stemborer pests whose control has remained a challenge. The International Centre of Insect Phys...

A better understanding of the chemical cues employed by parasitoids to locate their herbivore hosts will contribute towards effective exploitation of parasitoids as biological control agents against damaging crop pests. The current study was conducted to establish key bioactive compounds mediating behavioural response in the parasitic wasp Cotesia...

The parasitic weeds Striga asiatica and Striga hermonthica cause high yield losses in rain-fed upland rice in Africa. Two resistance classes (pre- and post-attachment) and several resistant genotypes have been identified among NERICA (New Rice for Africa) cultivars under laboratory conditions (in vitro) previously. However, little is known about ex...

Abstract 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 effectivenes...

To reduce the need for seasonal inputs, crop protection will have to be delivered via the seed and other planting material. Plant secondary metabolism can be harnessed for this purpose by new breeding technologies, genetic modification and companion cropping, the latter already on-farm in sub-Saharan Africa. Secondary metabolites offer the prospect...

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 th...

Maternal host choices during oviposition by herbivorous insects determine the fitness of their offspring and may be influenced by environmental changes that can alter host-plant quality. This is of particular relevance to ‘push-pull’ cropping systems where host preferences are exploited to manage insect pest populations. We tested how drought stres...

Production of Napier grass, Pennisetum purpureum, the most important livestock fodder in western Kenya, is severely constrained by Napier stunt disease (Ns-disease). Understanding farmers’ knowledge, perceptions and practices is a prerequisite to establishing an effective disease management approach. Using a random sample of 150 farmers drawn from...

Farming systems for pest control, based on the stimulo-deterrent diversionary strategy or push-pull system, have become an important target for sustainable intensification of food production. A prominent example is push-pull developed in sub-Saharan Africa using a combination of companion plants delivering semiochemicals, as plant secondary metabol...

Allelopathy offers a direct opportunity for the host plant to counter development of a parasitic plant by deploying antagonistic secondary metabolites at the early stages of infestation. Little progress has been made in exploiting allelopathy for controlling parasitic plants, largely because of weakened defence secondary metabolism of crop plants a...

The Lepidopteran stemborer Chilo partellus is a key constraint to cereal production in most resource-poor farming systems as it causes damage to the crop, accruing up to 80%. When plants are damaged by herbivorous insects, they produce herbivore-induced plant volatiles (HIPVs) which can act as repellants for these insect pests and as attractants fo...

The parasitic weed Striga hermonthica is a major constraint to maize production in sub-Saharan Africa and causes serious food insecurity. We discovered serendipitously an effective control method for the weed that involves intercropping cereals with the fodder legume, silverleaf desmodium, Desmodium uncinatum (Jacq.) DC., through mechanisms that in...

Cotton (Gossypium hirsutum L.) production in western Kenya is severely affected by insect pests, resulting in poor yields in spite of the growing demand for the commodity. One of the key constraints to establishing effective pest management approaches for smallholder farmers is the lack of adequate information about farmers' knowledge, perceptions...

The boll weevil, Anthonomus grandis, has been monitored through deployment of traps baited with aggregation pheromone components. However, field studies have shown that the number of insects caught in these traps is significantly reduced during cotton squaring, suggesting that volatiles produced by plants at this phenological stage may be involved...

Empirical exploitation of insect reception and detection at the peripheral neurosensory level has been extremely valuable for identifying pheromones and other semiochemicals, mainly by electroantennogram or single cell preparations coupled with capillary gas chromatography. Differential sensitivity to semiochemicals at the single‐cell level has all...

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 s...

Push-pull technology (PPT) is currently and widely promoted as a control measure for stemborers, Striga weed and soil fertility improvement in maize fields in western Kenya in order to improve on cereal production. Since it is a new and relatively knowledge-intensive technology, access information about its efficacy is critical for maximum adoption...

Hyparrhenia rufa is a thatching grass commonly found throughout the tropics where it also serves as valuable cattle fodder and border grass to prevent soil erosion (Skerman & Riveros, 1990). In June 2010, we observed some H. rufa plantsin the wild grasslands at several locations of Lambwe Valley in western Kenya that were stunted and appeared bushy...

Natural enemies respond to herbivore-induced plant volatiles (HIPVs), but an often overlooked aspect is that there may be genotypic variation in these 'indirect' plant defence traits within plant species. We found that egg deposition by stemborer moths (Chilo partellus) on maize landrace varieties caused emission of HIPVs that attract parasitic was...

The push-pull technology (PPT) has widely been disseminated to control insect stemborers [Chilo partellus and Busseola fusca] and Striga weeds [Striga hermonthica and Striga asiatica] in maize fields in Kenya. This study examined farmers' preferences for various dissemination pathways in order to proffer better targeting of resources in an optimal...

Napier grass (Pennisetum purpureum Schumach), the main fodder crop in eastern Africa, has recently been severely affected by Napier stunt disease, which is caused by phytoplasma. We have recently confirmed that a leafhopper, Maiestas banda (Kramer) transmits phytoplasma in Napier grass in Kenya. Several other species of leafhoppers (Cicadellidae) a...

Push-pull technology (www.push-pull.net) is based on a novel cropping system developed by the International Centre of Insect Physiology and Ecology, Rothamsted Research (UK) and national partners for integrated pest, weed and soil management in cereal-livestock farming systems. Stemborers are attracted to Napier grass (Pennisetum purpureum), a trap...

Female lepidopterans can display a hierarchy of preference among potential host species, a trait thought to arise from the balance between attractants and deterrents to which the insects respond. Host plant ranking by moths and larvae of Chilo partellus Swinhoe (Lepidoptera: Crambidae), an important pest of cereals in Africa, was investigated, and...

Lepidopteran stemborers and parasitic weeds in the genus Striga are major constraints to efficient production of cereals, the most important staple food crops in Africa. Smallholder farmers are resource constrained and unable to afford expensive chemicals for crop protection. Development of a push–pull approach for integrated pest and weed manageme...

Parasitic plants, through a range of infestation strategies, can attack crop plants and thereby require management. Because such problems often occur in resource-poor farming systems, companion cropping to manage parasitic plants is an appropriate approach. Many examples of companion cropping for this purpose have been reported, but the use of catt...

Bermuda grass (=Star grass), Cynodon dactylon , is a perennial plant of the family Poaceae that is native to the African Savannah but is now widely distributed over many warm countries of the world (Marcone et al ., 1997). C. dactylon plants…

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. intortu...