Epidemiological assessment of cassava mosaic disease in Central African Republic reveals the importance of mixed viral infection and poor health of plant cuttings

Zinga, Innocent; Chiroleu, Frédéric; Legg, J.P.; Lefeuvre, Pierre; Komba, Ephrem Kosh; Semballa, Silla; Yandia, Simplice Prosper; Mandakombo, Noella; Reynaud, Bernard; Lett, Jean‐Michel

doi:10.1016/j.cropro.2012.10.010

Cited by 36 publications

(47 citation statements)

References 29 publications

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“…These values are higher than those found by Zinga et al. () in Central African Republic and Sseruwagi et al. () in Uganda which, using the same sampling method, found on average 1.5 and 7.1 adults per plant, respectively.…”

Section: Discussioncontrasting

confidence: 67%

“…Moreover, this abundance increased in Koubri and Tiébélé from 2015 to 2016. These values are higher than those found byZinga et al (2013) in Central African Republic andSseruwagi et al (2004) in Uganda which, using the same sampling method, found on average 1.5 and 7.1 adults per plant, respectively.Our results provide compelling evidence that Burkina Faso is facing an upsurge of superabundant whiteflies. This might be linked to theF I G U R E 3 Average abundance of Bemisia tabaci on the host plants.…”

contrasting

confidence: 66%

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Abundance of Bemisia tabaci Gennadius (Hemiptera: Aleyrodidae) and its parasitoids on vegetables and cassava plants in Burkina Faso (West Africa)

Romba

Gnankiné

Drabo

et al. 2018

Ecology and Evolution

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The whitefly Bemisia tabaci is a pest of many agricultural and ornamental crops worldwide and particularly in Africa. It is a complex of cryptic species, which is extremely polyphagous with hundreds of host plants identified around the world. Previous surveys in western Africa indicated the presence of two biotypes of the invasive MED species (MED‐Q1 and MED‐Q3) living in sympatry with the African species SSA and ASL. This situation constitutes one of the rare cases of local coexistence of various genetic entities within the B. tabaci complex. In order to study the dynamics of the distribution and abundance of genetic entities within this community and to identify potential factors that could contribute to coexistence, we sampled B. tabaci populations in Burkina Faso in 2015 and 2016 on various plants, and also their parasitoids. All four genetic entities were still recorded, indicating no exclusion of local species by the MED species. While B. tabaci individuals were found on 55 plant species belonging to eighteen (18) families showing the high polyphagy of this pest, some species/biotypes exhibited higher specificity. Two parasitoid species (Eretmocerus mundus and Encarsia vandrieschei) were also recorded with E. mundus being predominant in most localities and on most plants. Our data indicated that whitefly abundance, diversity, and rate of parasitism varied according to areas, plants, and years, but that parasitism rate was globally highly correlated with whitefly abundance suggesting density dependence. Our results also suggest dynamic variation in the local diversity of B. tabaci species/biotypes from 1 year to the other, specifically with MED‐Q1 and ASL species. This work provides relevant information on the nature of plant–B. tabaci‐parasitoid interactions in West Africa and identifies that coexistence might be stabilized by niche differentiation for some genetic entities. However, MED‐Q1 and ASL show extensive niche overlap, which could ultimately lead to competitive exclusion.

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Section: Discussioncontrasting

confidence: 67%

contrasting

confidence: 66%

Abundance of Bemisia tabaci Gennadius (Hemiptera: Aleyrodidae) and its parasitoids on vegetables and cassava plants in Burkina Faso (West Africa)

Romba

Gnankiné

Drabo

et al. 2018

Ecology and Evolution

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“…In an epidemiological point of view, the synergy between the two virus strains in case of co-infection being one of the main factors explaining the severe CMD observed in large cropping areas in RCA (Zinga et al 2013), such a varietal resistance could strongly contribute to contain the pandemic. All the other genotypes with less than 10% of plants presenting very mild symptoms can be considered as highly resistant.…”

Section: Discussionmentioning

confidence: 99%

“…In the case of most resistant genotypes, only ACMV was detected on some plants in Damara therefore suggesting that varietal resistance strongly reduces the risk of the presence of EACMV-UG variant, or co-infection with both strains. In an epidemiological point of view, the synergy between the two virus strains in case of co-infection being one of the main factors explaining the severe CMD observed in large cropping areas in RCA (Zinga et al 2013), such a varietal resistance could strongly contribute to contain the pandemic.…”

Section: Discussionmentioning

confidence: 99%

“…Complete genome sequencing demonstrated the occurrence in CAR of two viral species that were shown to be closely related to the African cassava mosaic virus (ACMV) and the East African cassava mosaic virus-Ugandan variant (EACMV-UG), with an overall nucleotide sequence identity of 97 and 99%, respectively (Zinga et al 2013). These viruses belong to the genus Begomovirus (Family Geminiviridae) transmitted by whitefly Bemisia tabaci (Gennadius; Harrison et al 1997;Otim-Nape et al 2000).…”

Section: Introductionmentioning

confidence: 99%

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Evaluation of Cassava Cultivars for Resistance to Cassava Mosaic Disease and Yield Potential in Central African Republic

Zinga

Chiroleu

Zango

et al. 2016

Journal of Phytopathology

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Eleven cassava genotypes were tested against cassava mosaic disease (CMD) and compared to a local susceptible cultivar in field conditions from June 2011 to July 2012 in Central African Republic (CAR) at two sites representative of the savanna (Damara) and forest (Pissa) zones of the country. The mean number of whiteflies observed on plants varied among genotypes within each site, but was found nearly three times higher at Damara than at Pissa, resulting in a CMD incidence nearly five times higher at Damara than at Pissa. However, no relation was observed between the number of insect on the plants and the level of susceptibility/resistance of the genotypes. The difference of disease pressure between the two sites revealed high level of resistance in several genotypes, while some other ones indicated rather only a partial resistance. Nevertheless, none of the genotypes tested was found immune, in the end, the virus being detected at least in one site in every genotype, including those ones presenting no symptoms in both sites. The impact of CMD on yield components was assessed on the local susceptible check and three partially resistant genotypes, showing that the disease has no significant effect on the tuberous roots number as well as their weight in both sites. The yield potential varied among different genotypes and between the two sites, the mean number of tuberous roots as well as their mean weight being higher in Damara than in Pissa. This study identified highly resistant genotypes such as ‘Gabon’ that performed well in both sites, and ‘91/02322’ that was symptomless and presented a yield potential equivalent to the local check. These genotypes could be distributed to growers with the main advantage to be resistant to CMD and, therefore, reducing the risk to spread sources of inoculum all over the cassava cropping areas in the country.

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Octocoral co-infection as a balance between host immunity and host environment

2017

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Co-infection is the reality in natural populations, but few studies incorporate the players that matter in the wild. We integrate the environment, host demography, two parasites, and host immunity in a study of co-infection to determine the drivers of parasite interactions. Here, we use an ecologically important Caribbean sea fan octocoral, Gorgonia ventalina, that is co-infected by a copepod and a labyrinthulid protist. We first expanded upon laboratory studies by showing that immune suppression is associated with the labyrinthulid in a natural setting. Histological analyses revealed that immune cells (amoebocytes) were significantly suppressed in both labyrinthulid infections and co-infections relative to healthy sea fans, but remained unchanged in copepod infections. However, surveys of natural coral populations demonstrated a critical role for the environment and host demography in this co-infection: the prevalence of copepod infections increased with sea fan size while labyrinthulid prevalence increased with water depth. Although we predicted that immune suppression by the labyrinthulid would facilitate copepod infection, the two parasites did not co-occur in the sea fans more often than expected by chance. These results suggest that the distinct ecological drivers for each parasite overwhelm the role of host immune suppression in determining the distribution of parasites among hosts. This interplay of the environment and parasite-mediated immune suppression in sea fan co-infection provides insights into the factors underlying co-occurrence patterns in wild co-infections. Moving forward, simultaneous consideration of co-occurring parasites, host traits, and the environmental context will improve the understanding of host - parasite interactions and their consequences.

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Epidemiological assessment of cassava mosaic disease in Central African Republic reveals the importance of mixed viral infection and poor health of plant cuttings

Cited by 36 publications

References 29 publications

Abundance of Bemisia tabaci Gennadius (Hemiptera: Aleyrodidae) and its parasitoids on vegetables and cassava plants in Burkina Faso (West Africa)

Abundance of Bemisia tabaci Gennadius (Hemiptera: Aleyrodidae) and its parasitoids on vegetables and cassava plants in Burkina Faso (West Africa)

Evaluation of Cassava Cultivars for Resistance to Cassava Mosaic Disease and Yield Potential in Central African Republic

Octocoral co-infection as a balance between host immunity and host environment

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