Sampling Mononychellus tanajoa (Acari: Tetranychidae) on cassava in Africa

Density-specific sampling plans were developed under African conditions for the exotic spider mite, Mononychellus tanajoa (Bondar), a serious pest of cassava, Manihot esculenta. The within-plant distribution of Mononychellus tanajoa was found to favour new foliage, regardless of time of planting or plant age. Consequently, the first developed leaf near the top of the foliage was selected as the sampling unit and related to whole plant populations of M. tanajoa. The relationship between the mite population's variance and mean as measured by Taylor's Power Law proved to be stable over a range of planting dates, seasons and locations. Two binomial sampling plans, one based on Taylor's dispersion parameters and another based on direct field observations, were developed and compared. Binomial sampling, appropriate only for densities below 30 mites per leaf, was replaced by an enumerative procedure based on a ‘quick count' protocol at higher mite densitie

Cassava green mite intervention technologies

The cassava green mite, Mononychellus tanajoa (Bondar) (Acari: Tetranychidae), became a conspicuous pest of cassava soon after its accidental introduction into Africa in the early 1970s. It has since spread across the entire cassava belt of the continent causing an estimated 30 to 80 percent reduction in yield and threatening the food security of resource-poor farmers. Biological control, host plant resistance and cultural practices are all promising pest management interventions. The classical biological control initiative coordinated by the International Institute of Tropical Agriculure (IITA) is currently the largest single cassava green mite pest management activity in Africa. Recent successes with several exotic phytoseiid mite predators and the introduction of a virulent strain of an exotic fungal pathogen enhances the prospects for classical biological control in targeted ecologies. Evidence of moderate genetic resistance prompted an increasing number of cassava breeding programmes to screen for mite damage symptoms during germ plasm selection. New varieties are now being developed and their impact on the pest evaluated on-farm. However, adoption and distribution of new cultivars continue to be slow. Multi-trophic cassava agroecosystem research identified cultural practices that hinder the development of cassava green mite populations. Cultivars, soil fertility, time of planting, cropping system and time of harvest all influence the build-up of damaging pest populations. Packaging and disseminating this information to extension agents and farmers remains to be done. Much of the recent plant protection effort has focused on developing technologies without appropriate diagnosis, and relatively little effort has been made to implement, evaluate and integrate these interventions in the field. New intervention technologies will be difficult to introduce where cassava is of secondary economic importance. However, as the cassava market expands, more demand will be made for appropriate cassava green mite management solutions. Integrating these interventions into a comprehensive plant protection strategy remains a challenge.Key Words: Cassava, Mononychellus tanajoa, classical biological control, bost plant resistance, cultural control.  L'acarien vert du manioc, MononycheUus tanajoa (Bondar) (Acari: Tetranychidae), est devenu un ravageur notoire du manioc peu après son introduction accidentelle en Afrique au début des années 70. Depuis, il s'est propagé dans toute la zone de production du manioc du continent, causant des baisses de rendement estimées 30-80% et menaçant la sécurité alimentaire des paysans à faibles ressources. La lutte biologique, la résistance de la plante hôte et les pratiques culturales sont toutes des interventions prometteuses en matière de protection. L'initiative de lutte biologique classique, dont la coordination est assurèe par l'IITA, est actuellement la plus vaste activité de lutte consacrée à un seul ravageur, en l'occurence l'acarien vert du manioc. Les récents succés remportés avec plusieurs prédateurs phytoséiides exotiques, et l'introduction d'une souche virulente de champignon pathogène exotique, renforcent les perspectives de lutte biologique classique dans des écologies ciblées. Certaines manifestations de résistance génétique modérée incitent de plus en plus de programmes d'amélioration du manioc à cribler et sélectionner du germoplasme résistant aux acariens. De nouvelles variétés sont actuellement mises au point, et leur impact sur Ie ravageur est evalue en milieu réel. Cependant, l'adoption et la diffusion des nouveaux cultivars sont encore lentes. La recherche sur les méchanismes multitrophiques de l'écosysteme manioc a permis d'identifier des pratiques culturales qui entravent le développement des populations d'acariens verts. Les cultivars, la fertilité du sol, la date de la plantation, le systéme cultural et la date de la récolte sont autant de facteurs qui influent sur l'accroissement de la population des ravageurs. ll s'agit de conditionner ces informations et de les diffuser aux vulgarisateurs et aux paysans. Jusqu'ici, la protection des végétaux se consacrait essentiellement à la mise au point de technologies sans diagnostic préalable et relativement peu d'efforts étaient consentis pour mettre en oeuvre, évaluer et intégrer ces interventions au champ. Les nouvelles techniques d'intervention seront difficiles à introduire là où le manioc n'a qu'une importance économique secondaire. Toutefois, avec l'expansion du marché du manioc, la demande de solutions appropriées de lutte contre l'acarien vert du manioc augmentera. L'intégration de ces interventions dans une stratégie globale de protection végétale reste un défi à relever.Mots Cles: Manioc, Mononychellus tanajoa, lutte biologique classique, résistance de la plante-hôte, pratiques culturale

Cassava Green Mite Intervention Technologies

The Cassava green mite, Mononychellus tanajoa (Bonder) (Acari: Tetranychidae), became a conspicuous pest of cassava soon after its accidental introduction into Africa in the early 1970s. It has since spread across the entire cassava belt of the continent causing and estimated 30 to 80 percent reduction in yield and threatening the food security of resource- poor farmers. Biological control, host plant resistance and cultural practices are all promising pest management interventions. The classical biological control initiative coordinated by the International Institute of Tropical Agriculture (IITA) is currently the largest single cassava green mite pest management activity in Africa. Recent successes with several exotic phytoseiid mite predators and the introduction of a virulent strain of an exotic fungal pathogen enhances the prospects for classical biological control in targeted ecologies. Evidence of moderate genetic resistance prompted an increasing number of cassava breeding programmes to screen for mite damage symptoms during germplasm selection. New varieties are now being developed and their impact on the pest evaluated on-farm. However, adoption and distribution of new cultivars continue to slow. Muti-trophic cassava agroecosystem research identified cultural practices that hinder the development of cassava green mite population. Cultivars, soil fertility, time of planting, cropping system and time of harvest all influence the build-up of damaging pest populations. Packaging and disseminating this information to extension agents and farmers remains to be done. Much of the recent plant protection effort has focused on developing technologies without appropriate diagnosis, and relatively little effort has been made to implement, evaluate and integrate these interventions in the field. New intervention technologies will be difficult to introduce where cassava is of secondary economic importance. However, as the cassava market expands, more demand will be made for appropriate cassava green mite management solutions. Integrating these interventions into a comprehensive plant protection strategy remains a challenge

Cassava Green Mite Intervention Technologies

The Cassava green mite, Mononychellus tanajoa (Bonder) (Acari: Tetranychidae), became a conspicuous pest of cassava soon after its accidental introduction into Africa in the early 1970s. It has since spread across the entire cassava belt of the continent causing and estimated 30 to 80 percent reduction in yield and threatening the food security of resource- poor farmers. Biological control, host plant resistance and cultural practices are all promising pest management interventions. The classical biological control initiative coordinated by the International Institute of Tropical Agriculture (IITA) is currently the largest single cassava green mite pest management activity in Africa. Recent successes with several exotic phytoseiid mite predators and the introduction of a virulent strain of an exotic fungal pathogen enhances the prospects for classical biological control in targeted ecologies. Evidence of moderate genetic resistance prompted an increasing number of cassava breeding programmes to screen for mite damage symptoms during germplasm selection. New varieties are now being developed and their impact on the pest evaluated on-farm. However, adoption and distribution of new cultivars continue to slow. Muti-trophic cassava agroecosystem research identified cultural practices that hinder the development of cassava green mite population. Cultivars, soil fertility, time of planting, cropping system and time of harvest all influence the build-up of damaging pest populations. Packaging and disseminating this information to extension agents and farmers remains to be done. Much of the recent plant protection effort has focused on developing technologies without appropriate diagnosis, and relatively little effort has been made to implement, evaluate and integrate these interventions in the field. New intervention technologies will be difficult to introduce where cassava is of secondary economic importance. However, as the cassava market expands, more demand will be made for appropriate cassava green mite management solutions. Integrating these interventions into a comprehensive plant protection strategy remains a challenge

Ecologically Sustainable Cassava Plant Protection (ESCaPP): A model for Environmentally Sound Pest Management in Africa

Integrating the management of cassava pests into a strategy with meets the needs of individual farmers requires a conceptual framework for development and implementation. The Ecologically Sustainable Cassava Plant Protection (ESCaPP) project which began in 1993 in West Africa provides such a working model. ESCaPP is a regional project to develop, test and adapt sustainable cassava plant protection technologies for the most important arthropod, pathogen and weed pests in West Africa. Multi-disciplinary teams of national plant protection experts join regionally with international experts to share expertise and pool efforts across agroecologies. Project activities are divided into three interrelated and overlapping phases. The major cassava pests are being identified in targeted agroecologies through initial diagnostic surveys. In the second phase, farmers' participation highlights the development and testing of appropriate intervention technologies. Concurrently, in-service training of researchers, extension agents and farmers in the principles and practices of sustainable crop production and protection is provided. Post graduate training will be provided to women to strengthen their professional resource base in plant protection development activities. the third phase is an evaluation of the training objectives and technology implementation. Unique features of the project include nationally seconded multi disciplinary teams, shared local expertise on a regional basis and activities based on local diagnoses. The project is a collaborative effort between the International Institute of Tropical Agriculture (IITA), national plant protection staff, extension workers and farmers in Cameroon, Nigeria, Benin and Ghana, with a parallel component in Brazil involving Centro Internacional de Agricultura Tropical (CIAT) and Empresa Brasileira de Pesquisa Agropecüaria (EMBRAPA). The research, training, implementation and evaluation paradigm used in this project can serve as a model for developing appropriate plant protection technologies and pest management strategies for other cropping system

Ecologically Sustainable Cassava Plant Protection (ESCaPP): A model for Environmentally Sound Pest Management in Africa

Integrating the management of cassava pests into a strategy with meets the needs of individual farmers requires a conceptual framework for development and implementation. The Ecologically Sustainable Cassava Plant Protection (ESCaPP) project which began in 1993 in West Africa provides such a working model. ESCaPP is a regional project to develop, test and adapt sustainable cassava plant protection technologies for the most important arthropod, pathogen and weed pests in West Africa. Multi-disciplinary teams of national plant protection experts join regionally with international experts to share expertise and pool efforts across agroecologies. Project activities are divided into three interrelated and overlapping phases. The major cassava pests are being identified in targeted agroecologies through initial diagnostic surveys. In the second phase, farmers' participation highlights the development and testing of appropriate intervention technologies. Concurrently, in-service training of researchers, extension agents and farmers in the principles and practices of sustainable crop production and protection is provided. Post graduate training will be provided to women to strengthen their professional resource base in plant protection development activities. the third phase is an evaluation of the training objectives and technology implementation. Unique features of the project include nationally seconded multi disciplinary teams, shared local expertise on a regional basis and activities based on local diagnoses. The project is a collaborative effort between the International Institute of Tropical Agriculture (IITA), national plant protection staff, extension workers and farmers in Cameroon, Nigeria, Benin and Ghana, with a parallel component in Brazil involving Centro Internacional de Agricultura Tropical (CIAT) and Empresa Brasileira de Pesquisa Agropec\ufcaria (EMBRAPA). The research, training, implementation and evaluation paradigm used in this project can serve as a model for developing appropriate plant protection technologies and pest management strategies for other cropping system

Sampling Mononychellus tanajoa (Acari: Tetranychidae) on cassava in Africa

ISSN:0007-4853ISSN:1475-267