Occurrence and distribution of cassava pests and diseases in Rwanda

Night, G.; Asiimwe, Peter; Gashaka, G.; Nkezabahizi, D.; Legg, J.P.; Okao-Okuja, Geoffrey; Obonyo, R.; Nyirahorana, Concilie; Mukakanyana, C.; Mukase, F.; Munyabarenzi, I.; Mutumwinka, M.

doi:10.1016/j.agee.2011.01.014

Cited by 27 publications

(26 citation statements)

References 18 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…Furthermore, CBSD was mainly observed in the improved CMD-resistant cultivars introduced from neighbouring Uganda that were subsequently propagated and distributed to farmers in Rwanda. This was done with a view to controlling the CMD pandemic into Rwanda two decades ago (Night et al, 2011). The improved materials may not have been CBSD-free and neither were they CBSD-resistant before being introduced, as at that time CBSD was not considered a problem.…”

Section: Discussionmentioning

confidence: 99%

Cassava brown streak disease in Rwanda, the associated viruses and disease phenotypes

et al. 2017

View full text Add to dashboard Cite

Cassava brown streak disease (CBSD) was first observed on cassava (Manihot esculenta) in Rwanda in 2009. In 2014 eight major cassava‐growing districts in the country were surveyed to determine the distribution and variability of symptom phenotypes associated with CBSD, and the genetic diversity of cassava brown streak viruses. Distribution of the CBSD symptom phenotypes and their combinations varied greatly between districts, cultivars and their associated viruses. The symptoms on leaf alone recorded the highest (32.2%) incidence, followed by roots (25.7%), leaf + stem (20.3%), leaf + root (10.4%), leaf + stem + root (5.2%), stem + root (3.7%), and stem (2.5%) symptoms. Analysis by RT‐PCR showed that single infections of Ugandan cassava brown streak virus (UCBSV) were most common (74.2% of total infections) and associated with all the seven phenotypes studied. Single infections of Cassava brown streak virus (CBSV) were predominant (15.3% of total infections) in CBSD‐affected plants showing symptoms on stems alone. Mixed infections (CBSV + UCBSV) comprised 10.5% of total infections and predominated in the combinations of leaf + stem + root phenotypes. Phylogenetic analysis and the estimates of evolutionary divergence, using partial sequences (210 nt) of the coat protein gene, revealed that in Rwanda there is one type of CBSV and an indication of diverse UCBSV. This study is the first to report the occurrence and distribution of both CBSV and UCBSV based on molecular techniques in Rwanda.

show abstract

Section: Discussionmentioning

confidence: 99%

Cassava brown streak disease in Rwanda, the associated viruses and disease phenotypes

et al. 2017

View full text Add to dashboard Cite

show abstract

“…Survey of cassava across Tanzania during the 1993–1994 growing season showed that on average 27% of plants had CMD symptoms, of which 3% could be attributed to B. tabaci transmission, compared with 24% of infections to the use of infected cuttings (Legg & Raya, 1998). More recently, it has been shown that a greater proportion of CMD is cutting borne compared with being vectored by B. tabaci (Night et al , 2011). A modelling study exploring CBSD spread showed that in a scenario with whitefly dispersal alone, large-scale epidemics were less likely than when trade of infected cuttings is also included in the model (McQuaid et al , 2017).…”

Section: Plant Virus Transmission By B Tabacimentioning

confidence: 99%

“…Katono et al , 2015). Severity of cassava green mite (CGM; Mononychellus tanajoa ) and CMD were higher on local cultivars of cassava, although B. tabaci populations were higher on improved cultivars (Night et al , 2011). To determine which cultivars showed some level of phenotypic resistance or tolerance to B. tabaci , 19 cultivars were exposed to B. tabaci for colonization.…”

Section: Biotic Factorsmentioning

confidence: 99%

“…Intercropping cassava with cowpea has been shown to decrease numbers of B. tabaci in Colombia (Gold et al , 1989). Results of surveys in Uganda in 2007 showed that intercropped cassava had significantly less B. tabaci than monocrops (Night et al , 2011). Experiments intercropping cassava with Vigna unguiculata and Vigna radiata (cowpea and green gram mung bean) showed reduced B. tabaci populations and severity of CMD.…”

Section: Biotic Factorsmentioning

confidence: 99%

See 1 more Smart Citation

Cassava whitefly,Bemisia tabaci(Gennadius) (Hemiptera: Aleyrodidae) in East African farming landscapes: a review of the factors determining abundance

Macfadyen

Paull

Boykin

et al. 2018

Bull. Entomol. Res.

View full text Add to dashboard Cite

Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae) is a pest species complex that causes widespread damage to cassava, a staple food crop for millions of households in East Africa. Species in the complex cause direct feeding damage to cassava and are the vectors of multiple plant viruses. Whilst significant work has gone into developing virus-resistant cassava cultivars, there has been little research effort aimed at understanding the ecology of these insect vectors. Here we assess critically the knowledge base relating to factors that may lead to high population densities of sub-Saharan African (SSA) B. tabaci species in cassava production landscapes of East Africa. We focus first on empirical studies that have examined biotic or abiotic factors that may lead to high populations. We then identify knowledge gaps that need to be filled to deliver sustainable management solutions. We found that whilst many hypotheses have been put forward to explain the increases in abundance witnessed since the early 1990s, there are little published data and these tend to have been collected in a piecemeal manner. The most critical knowledge gaps identified were: (i) understanding how cassava cultivars and alternative host plants impact population dynamics and natural enemies; (ii) the impact of natural enemies in terms of reducing the frequency of outbreaks and (iii) the use and management of insecticides to delay the development of resistance. In addition, there are several fundamental methodologies that need to be developed and deployed in East Africa to address some of the more challenging knowledge gaps.

show abstract

“…Cette variété serait plus attractive aux acariens et donc plus exposée aux attaques du ravageur. Selon Night et al (2011), la gravité des attaques de l'acarien vert du manioc était plus élevée sur les cultivars locaux. Les attaques de l'acarien vert peuvent entraîner des pertes de rendement allant de 20 à 80% sur le manioc (Mahungu et al, 2014).…”

Section: Distribution Des Populations De La Mouche Blanche (Bemisia Tunclassified

Inventaire et distribution des principaux arthropodes ravageurs du manioc (<i>Manihot esculenta</i> CRANTZ) au Tchad

Abderahim¹,

Diatte²,

Labou³

et al. 2019

Int. J. Bio. Chem. Sci

View full text Add to dashboard Cite

Tel : +235 66 28 95 01 ; +221 78 525 69 29 REMERCIEMENTS Nous remercions profondément la Commission Nationale de Formation des Formateurs (CONFOFOR) du Tchad pour le financement de cette étude. RESUME Le manioc joue un rôle important dans l'alimentation des populations. Cependant les ravageurs constituent une contrainte à sa production. Dans le but d'identifier les arthropodes ravageurs du manioc (M. esculenta) et d'étudier leur distribution, une étude a été réalisée au Tchad. Les échantillonnages ont été effectués dans les sites de Kobdogue, Moya, Faya et Yaroungou. Tous les ravageurs rencontrés ont été récoltés et identifiés. Huit espèces de ravageurs ont été répertoriées : Phenacoccus manihoti, Bemisia tabaci, Mononychellus tanajoa, Zonocerus variegatus, Odontotermes sp aff erraticus, Aromia moschata, Camponotus ligniperda et Panonychus ulmi. La cochenille farineuse (P. manihoti) a été observée dans tous les sites. Elle est plus importante à Faya (50,76%) et à Kobdogue (31,64%). L'acarien vert M. tanajoa et la mouche blanche B. tabaci, sont respectivement plus importants à Kobdogue (50,63% et 39,17%) et à Faya (18,98% et 24,62%). La variété Ngaloum nguegdje est la plus attaquée par les ravageurs : la cochenille farineuse (n = 14087), l'acarien vert (n = 524) et la mouche blanche (n = 3102) comparée à la variété Kangaba respectivement (n = 3042), (n = 229) et (n = 1675). Ces résultats permettront d'adapter une stratégie de gestion des arthropodes ravageurs du manioc au Tchad. ABSTRACTCassava plays an important role in the diet of the population. However, pests are a constraint to its production. In order to identify arthropod pests of cassava (M. esculenta) and study their distribution, a study was carried out in Chad. Sampling was carried out at the sites of Kobdogue, Moya, Faya and Yaroungou. All pests encountered were harvested and identified. Eight pest species have been identified: Phenacoccus manihoti, Bemisia tabaci, Mononychellus tanajoa, Zonocerus variegatus, Odontotermes sp aff erraticus, Aromia moschata, Camponotus ligniperda and Panonychus ulmi. The mealybug (P. manihoti) was observed at all sites. It is higher in Faya (50.76%) and Kobdogue (31.64%). The green mite M. tanajoa and the white fly B. tabaci are more important in Kobdogue (50.63% and 39.17% respectively) and Faya (18.98% and 24.62%). The variety Ngaloum nguegdje is the most attacked by pests: mealybug (n = 14087), green mite (n = 524) and white fly (n = 3102) compared to the variety Kangaba respectively (n = 3042), (n = 229) and (n = 1675). These results will make it possible to adapt a strategy for the management of arthropod pests of cassava in Chad.

show abstract

Occurrence and distribution of cassava pests and diseases in Rwanda

Cited by 27 publications

References 18 publications

Cassava brown streak disease in Rwanda, the associated viruses and disease phenotypes

Cassava brown streak disease in Rwanda, the associated viruses and disease phenotypes

Cassava whitefly,Bemisia tabaci(Gennadius) (Hemiptera: Aleyrodidae) in East African farming landscapes: a review of the factors determining abundance

Inventaire et distribution des principaux arthropodes ravageurs du manioc (<i>Manihot esculenta</i> CRANTZ) au Tchad

Contact Info

Product

Resources

About