Potato virus Y (PVY, genus Potyvirus, family Potyviridae) causes high economic losses worldwide, especially in the production of seed potatoes (Solanum tuberosum). PVY control systems rely on measuring virus pressure and vector pressure in the field. Calculation of the vector pressure is based on the relative efficiency factors (REFs) of aphid species. These REFs express the transmission efficiency of aphid species in relation to the transmission efficiency of Myzus persicae, the most efficient vector of PVY. In this paper, we report on the determination of aphids' relative transmission efficiency factors (REFs) for isolates of the PVY strains PVYN, PVYNTN and PVYN-Wi. Biotype Mp2 of M. persicae was tested for its transmission efficiency for six PVY isolates (one PVYN, three PVYNTN and two PVYN-Wi isolates) and showed comparable average transmission efficiencies for all isolates. The transmission rate of this biotype for the six PVY isolates was set to 1 and Mp2 was used as an internal control in transmission experiments to determine the REFs of three other biotypes of M. persicae and 16 other aphid species (three biotypes per species when available) for the six PVY isolates. Comparing the calculated REFs for PVYN with the REFs reported in the previous century for PVYN, we observe overall comparable REFs, except for Aphis fabae, Aphis spp., Hyperomyzus lactucae, Macrosiphum euphorbiae and Rhopalosiphum padi, which have a lower REF in our experiments, and Aphis frangulae and Phorodon humuli, which have now a higher REF. Comparing the new REFs found for the PVYNTN strains with the new REFs for PVYN, we observe that they are overall comparable, except for A. frangulae (0.17 compared with 0.53) and Schizaphis graminum (0.05 compared with 0.00). Comparing the REFs calculated for PVYN-Wi with those calculated for PVYN, we can observe six aphid species with higher REFs (Acyrthosiphon pisum, A. fabae, Aphis nasturtii, Aphis spp., P. humuli and R. padi). Only the species A. frangulae shows a lower REF for PVYN-Wi compared with the transmission efficiency of PVYN. Three aphid species (Aulacorthum solani, Myzus ascalonicus and S. graminum) for which no REF was determined earlier were found to be capable to transmit PVY and their REFs were determine

Determination of aphid transmission efficiencies for N, NTN and Wilga strains of Potato virus Y

Potyviruses are the largest group of plant infecting RNA viruses that cause significant losses in a wide range of crops across the globe. The majority of viruses in the genus Potyvirus are transmitted by aphids in a non-persistent, non-circulative manner and have been extensively studied vis-a-vis their structure, taxonomy, evolution, diagnosis, transmission, and molecular interactions with hosts. This comprehensive review exclusively discusses potyviruses and their transmission by aphid vectors, specifically in the light of several virus, aphid and plant factors, and how their interplay influences potyviral binding in aphids, aphid behavior and fitness, host plant biochemistry, virus epidemics, and transmission bottlenecks. We present the heatmap of the global distribution of potyvirus species, variation in the potyviral coat protein gene, and top aphid vectors of potyviruses. Lastly, we examine how the fundamental understanding of these multi-partite interactions through multi-omics approaches is already contributing to, and can have future implications for, devising effective and sustainable management strategies against aphid-transmitted potyviruses to global agriculture.

Aphid Transmission of Potyvirus: The Largest Plant-Infecting RNA Virus Genus.

Changes in the metabolome and histopathology of Amaranthus hypochondriacus L. in response to Ageratum enation virus infection.

This monograph deals with all 95 names described in the Cucurbitaceae genus Coccinia and recognizes 25 species. Taxonomic novelties are Cocciniaadoensisvar.aurantiaca (C.Jeffrey) Holstein, stat. nov., Cocciniasessilifoliavar.variifolia (A.Meeuse) Holstein, stat. nov., and Cocciniaadoensisvar.jeffreyana Holstein, var. nov. For the 25 species 3157 collections were examined, of which 2024 were georeferenced to produce distribution maps. All species are distributed in sub-Saharan Africa with one species, Cocciniagrandis, extending from Senegal in West Africa east to Indonesia and being naturalized on Pacific Islands, in Australia, the Caribbean, and South America. Coccinia species are dioecious creepers or climbers with simple or bifid tendrils that occupy a range of habitats from arid scrubland, woodlands to lowland rainforest and mist forest. The corolla of Coccinia species is sympetalous, usually pale yellow to orange, and 1 to 4.5 cm long. Pollination is by bees foraging for pollen or nectar. After pollination, the developing ovary often exhibits longitudinal mottling, which usually disappears during maturation. All species produce berries with a pericarp in reddish colors (orange-red through to scarlet red), hence the generic name. The globose to cylindrical fruits contain numerous grayish-beige flat to lenticular seeds. Chromosome numbers are 2n = 20, 24, and 22 + XX/XY. Many Coccinia species are used for food, either as roasted tubers, greens as spinach, or the fruits as vegetables. Medicinal value is established in Cocciniagrandis, of which leaves and sap are used against diabetes.

Monograph of Coccinia Cucurbitaceae

Vegetables for the hot, humid tropics : a newsletter and annual communication among research workers

Virus infection of Lagenaria breviflora and Coccinia barteri were observed in Calabar, Nigeria during the 2005/2006 growing season. The viruses causing the diseases were characterized in this study. Diagnostic tools were host range, transmission studies, cytopathology, electron microscopy, Immunosorbent Electron Microscopy (ISEM), serology and coat protein gene sequencing. Evidence from biological, serological and sequence data confirmed that both viruses belong to the genus Potyvirus, family Potyviridae. Both were mechanically transmissible and also transmitted by Myzus persicae and Aphis gossyppi in a fore-gut manner. They also induced cytoplasmic inclusions in infected leaf tissues. The Lagenaria virus isolate has a coat protein molecular weight of 32.5 kDa and 35.0 kDa for Coccinia isolate. Of the two viruses only Lagenaria virus isolate showed cross reactivity with MWMV in DAS-ELISA. Both viruses reacted negatively with antisera to some notable cucurbit viruses in the same test, showed weak to moderate decorations with antisera to PRSV, TuMV and TeMV in immunosorbent electron microscopy (ISEM) tests. The Coccinia virus was, however, strongly decorated by antiserum to MWMV but no decoration with the Lagenaria virus. Comparison of the amino acid sequence data of the N-terminal regions of the coat proteins to that of MWMV reported from Sudan indicated 92% and 93% identities for the Coccinia and Lagenaria viruses, respectively. It is suggested that the virus isolates reported in the study be considered strains of the MWMV Sudan isolate. This is the first report of the occurrence of MWMV in Nigeria.

Strains of Moroccan watermelon mosaic virus isolated from Lagenaria breviflorus and Coccinia barteri in Calabar, southeastern Nigeria.

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Characterization and identification of a potyvirus causing mosaic disease of Cucurbita moschata Duch ex. Poir in Calabar, south east Nigeria.

Effects of Telfairia mosaic virus (TeMV) on the Chlorophyll Content and Photosynthetic Capabilities of Two Ecotypes of Telfairia occidentalis Hook. f. (Fluted Pumpkin)

Transmission Efficiency of Two Strains of Moroccan Watermelon Mosaic Virus by Two Clones of Aphis spiraecola (Patch)

Four commercial leafy vegetable farms in Lagos State were surveyed from October 1989 to September 1990 for the occurrence and prevalence of leafy vegetable viruses Mechanically transmissible viruses were isolated from Amaranthus hybridus, Celosia argentea, Cucurbita moschata, Telfairia occidentalis and Brassica oleracea , while virus-like symptoms (causal agents not sap-transmissible), were observed on Solanum macrocarpon  Two previously uncharacterized viruses, one each from C argentea and C moschata were isolated The identification of viruses such as telfairia mosaic virus (TeMV) and amaranthus mosaic virus (AMV), that had been reported in the literature, were confirmed on the basis of host range, symptomatology, insect transmission and particle morphology Virus-like symptoms were not observed on Corchorus olitorus and five other exotic vegetables Amaranthus mosaic virus and celosia mosaic virus (ClMV), the latter isolated for the first time in Nigeria in the course of this study, were recorded from all the farms and were therefore the most prevalent The incidence of AMV was 197% at Amuwo Odofin while it was 07% and 06% at Tejuoso and Abule Ado farms respectively For ClMV, an incidence of 275% was recorded at Amuwo Odofin while Tejuoso and Abule Ado had 06% and 14% respectively Telfairia mosaic virus and viruses on C moschata and B oleracea were limited to the Tejuoso farm Generally, virus incidence was higher during the wet season for most of the viruses Elimination of plant remains and volunteer crops may be exploited in the control of the viruses KEY WORDS: Survey, Leafy vegetables, viruses Global Jnl Pure & Applied Sciences Vol10(1) 2004: 61-67

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A.T. Owolabi

Papers

Strains of Moroccan watermelon mosaic virus isolated from Lagenaria breviflorus and Coccinia barteri in Calabar, southeastern Nigeria.

Characterization and identification of a potyvirus causing mosaic disease of Cucurbita moschata Duch ex. Poir in Calabar, south east Nigeria.

Effects of Telfairia mosaic virus (TeMV) on the Chlorophyll Content and Photosynthetic Capabilities of Two Ecotypes of Telfairia occidentalis Hook. f. (Fluted Pumpkin)

Transmission Efficiency of Two Strains of Moroccan Watermelon Mosaic Virus by Two Clones of Aphis spiraecola (Patch)

Occurrence and Prevalence of Viruses of Leafy Vegetables In Lagos, Nigeria