Incidence and diversity of viruses in cowpeas and weeds in the unmanaged farming systems of savanna zones in Nigeria

Fields surveys were conducted to assess the incidence of commonly known legume viruses on cowpeas and weed hosts within and around the cowpeas farms in nine locations across the three agro-ecological zones of Nigeria. Of 315 cowpea leaf samples collected and tested for eight viruses, 69.5% were found to be infected. Bean common mosaic virus-blackeye mosaic (BCMV-BlCM), genus Potyvirus had the highest incidence (70%) and was also the most prevalent (78%). Cowpea aphid-borne mosaic virus (CABMV, genus Potyvirus) had 64% as incidence, incidence of Southern bean mosaic virus (SBMV, genus Sobemovirus) was 21%. Bean pod mosaic virus (BPMV, genus Comovirus) was detected in 1% of the samples tested. Cowpea mosaic virus (CPMV, genus Comovirus) was undetected. Other viruses tested included Cowpea mottle virus (CPMoV, genus Carmovirus), Cucumber mosaic virus (CMV, genus Cucumovirus), and Cowpea mild mottle virus (CPMMV, genus Carlavirus). Multiple virus infections were detected in 68.0% of the infected cowpea leaf samples. The combination of BCMV-BlCM and CABMV was the most common, occurring in 76.4% of all samples. Virus incidence in weeds around the cowpea plots was 2.5% (9 out of 356) whereas 1.5% (5 out of 332) of the weeds collected within the cowpea plots were infected. Some of the weeds infected were Chromoleana odorata, Centrosema sp., Thithonia diversifolia and Talinum triangulare.     

Ultraviolet induced stress response in fresh cut cantaloupe

Changes in the composition of volatile compounds in cantaloupe melon (Cucumis melo L. var. reticulatus) as a result of UV induced stress were determined by gas chromatography-mass spectrometry (GC-MS). Several volatile ester compounds were present, of which twenty-seven were identified in fresh cut cantaloupe. Fruit exposure to UV light decreased the concentrations of most of the aliphatic esters by over 60% of the amounts present in the corresponding fresh cut fruit. Cyclic and acyclic terpenoids, including phytoalexin compounds beta-ionone, geranylacetone and terpinyl acetate, were also produced as a result of UV exposure for 15 and 60 min, respectively. beta-Ionone, when added to crushed cantaloupe (0.01% w/w) completely inhibited microbial growth in the fruit for 24 h at 20 degrees C. Geranylacetone and terpinyl acetate reduced the microbial population from 6.3x10(8) in the untreated control to 1.2x10(8) and 3.5x10(7) CFU/g respectively. The results indicate the potential use of UV induced stress for screening cantaloupe melon cultivars for disease resistance, and as a minimal processing method to extend the shelf life of fresh cut cantaloupe products.     

Plasmodium berghei: antiparasitic effects of orally administered hypoestoxide in mice

Hypoestoxide (HE) is a diterpene isolated from Hypoestes rosea (Acanthaceae), a plant indigenous to Nigeria. Previous studies demonstrated that HE exhibited potent anti-inflammatory and anti-cancer activities in well established animal models but weak in vitro activities in both the anti-inflammation and anti-cancer in vitro screening systems. We now report a similar observation in the in vitro and in vivo screening systems for antimalarial activity. The results indicate that while HE exhibits a relatively weak in vitro activity (IC(50) = 10 microM versus 0.11 microM for chloroquine) against different strains of cultured P. falciparum parasites, the dose of HE required to reduce parasitemia by 90% in Plasmodium berghei-infected mice, is much lower than standard antimalaria drugs (SD(90) = 250 microg/kg versus 5mg/kg for chloroquine). Furthermore, lower doses of HE were much more effective than higher doses in inhibiting parasite development. The implications of these findings are discussed.     

Black flies and Onchocerciasis: Knowledge,attitude and practices among inhabitants of Alabameta,Osun State,Southwestern, Nigeria

Background and objectivesThis study reports knowledge of residents of Alabameta community, Osun State, Nigeria on the bioecology and socio-economic burden of black flies and onchocerciasis.MethodsUsing structured questionnaires and Focus Group Discussion (FGD), a total of 150 community respondents participated in the study.ResultsThe knowledge of the residents on the existence of black flies in the community was significant (p<0.05) as all the 150 respondents confirmed the presence of black flies with the local name ‘Amukuru’ i.e causing itching. However, their lack of knowledge of the flies breeding site (104) (69%), prevention (134) (89%), cause (132) (88%), and treatment (133) (89%) of onchocerciasis was profound. Majority 147(98%) of the respondents reported that flies bite more in the wet season as against dry season 3(2%) and have a higher affinity (124) (82%) for biting the leg than any other part of the body. A larger percentage (89%) of the respondents are unaware of any medication for the treatment of onchocerciasis while 11% are aware. There had been no sensitization on onchocerciasis according to 89% of the respondents.ConclusionDue to lack of resident’s knowledge on black flies bioecology which may continuously expose them to the bite of the flies and ultimately infection, it is paramount that the Osun State government and the NTD implementing partner map out new public health education strategies during routine Mass Administration of Medicines with Ivermectin with a view to preventing onchocerciasis infection as well as man-vector contact.     

Protection of cowpea,Vigna unguiculata L. (Walp.) with Newbouldia laevis (Seem.) extracts against infestation by Callosobruchus maculatus (Fabricius)

Evaluation of protectant ability of Newbouldia laevis (Seem.) extracts against infestation by Callosobruchus maculatus in cowpea, Vigna unguiculata L. (Walp.) was carried out in the laboratory at ambient temperature of 28?±?2?°C and 70?±?5% relative humidity. Extracts from wood ash, leaf, stem and root bark were tested at different concentrations of 0, 1, 2, 3, 4 and 5%. One hundred per cent mortality of adult beetles was achieved at all concentrations within 72?h of treatment with extracts except in wood ash at 1% concentration, but they were significantly different (p?<?0.05) from the controls. All the extracts were still able to cause high beetle mortality after one, two and three months of cowpea storage at high concentrations (4 and 5%) except wood ash, although there was a slight decrease in mortality during the period of storage. All the extracts significantly (p?<?0.05) reduced oviposition and adult emergence of C. maculatus when compared with the controls although the reduction was higher at 5% concentration than others. Adult beetle emergence was completely prevented at higher concentrations (4 and 5%) except in wood ash. Both oviposition and adult emergence increased during the months of storage probably because of the slight reduction in the effectiveness of the extracts. The root bark extract was much more effective in reducing oviposition and adult emergence than others throughout the period of storage. The plant extracts of N. laevis was able to protect the cowpea seeds from damage and prevent weight loss. Cowpea seed damage and weight loss was significantly more (p?<?0.05) in the controls than other for the three-month duration probably because of the more adult emergence. The extracts from N. laevis did not adversely affect the germination of the protected seeds and seed germination ranged from 86.7 to 100%. It has been shown in this study that the extracts of N. laevis were effective against C. maculatus in cowpea although the root bark extract seemed to be the most effective while the wood ash extract was least effective. Their effectiveness, however, slightly decreased during the period of storage. N. laevis could be incorporated into pest management of stored cowpeas since the products are ecologically safe.     

Occurrence of latent virus infection in visually-rated cowpea (Vigna unguiculata L. Walp) seedlings

Abstract

The presence of latent infections was studied in five cowpeas varieties. Seeds of the varieties were planted and the seedlings inoculated with antigens from Cucumber mosaic virus (CMV) genus Cucumovirus, Bean common mosaic virus (BCMV) genus Potyvirus (Blackeye cowpea mosaic virus strain), Southern bean mosaic virus (SBMV) genus Sobemovirus and Cowpea mottle virus (CPMoV) genus Carmovirus seven days after planting. Seedlings expressing symptoms were rouged at two weeks after inoculation, while asymptomatic ones were subjected to serological indexing to detect the presence/absence of latent infection. Protein A-sandwich enzyme-linked immunosorbent assay (PAS ELISA) was employed for the serological detection of CMV, SBMV and CPMoV, while antigen-coated plate (ACP) ELISA was used to detect BCMV in the asymptomatic plants. Cowpea seedlings without virus symptoms but with positive serological reactions were considered as being latently infected. All of the inoculated TVu 1272 and SuVita-2 plants showed symptoms consistent with CMV and CPMoV infections, respectively. The rate of CMV latent infection was high in TVu 1179 (14.5%), low in SuVita-2 (1.3%) but not recorded in TVu 1272.     

Intestinal helminthiases and schistosomiasis among school children in an urban center and some rural communities in southwest Nigeria

Intestinal helminths and schistosomiasis among school children were investigated in an urban and some rural communities of Ogun State, southwest Nigeria. Fecal samples of 1,059 subjects (524 males, 535 females) aged 3-18 years were examined using direct smear and brine concentration methods between June 2005 and November 2006. The pooled prevalence of infection was 66.2%. Ascaris lumbricoides showed the highest prevalence (53.4%) (P < 0.001) followed by hookworms (17.8%), Trichuris trichiura (10.4%), Taenia sp. (9.6%), Schistosoma mansoni (2.3%), Strongyloides stercoralis (0.7%), Schistosoma haematobium (0.6%), and Enterobius vermicularis (0.3%). The prevalences of A. lumbricoides, hookworms, Taenia sp., S. mansoni, and S. stercoralis in the urban centre were similar (P > 0.05) to those in the rural communities. The fertile and infertile egg ratios of A. lumbricoides in the urban centre and the rural communities were 13: 1 and 3.7: 1, respectively. Each helminth had similar prevalences among both genders (P > 0.05). The prevalence of A. lumbricoides increased significantly with age (P < 0.001). The commonest double infections were Ascaris and hookworms, while the commonest triple infections were Ascaris, hookworms, and Trichuris. The study demonstrates the need for urgent intervention programmes against intestinal helminthiases and schistosomiasis in the study area.     

Fungi isolated from skins and pens of healthy animals in Nigeria

The mycoflora of 220 skin scrapings, hair, nail samples and pens’ materials of apparently healthy animals including cows, sheep, goats, rabbits, pigs and dogs were determined. Twenty eight species of fungi belonging to ten genera were recovered. Chrysosporium spp. were the most common and C. keratinophilum was recovered from all animals. Dermatophytes which are known causal agents of dermatophytosis were also isolated indifferent frequencies (Microsporum gypseum, M. canis, Trichophytonmentagrophytes, T. rubrum). This revised version was published online in June 2006 with corrections to the Cover Date.     

Extracellular amylase production by cassava-fermenting bacteria

Summary Fermentation of cassava tubers was accompanied by a gradual decrease in pH, increased amylase activity in the steep liquor, and increased microbial load and lactic acid concentration. Amylase-producing bacterial strains associated with cassava fermentation were isolated and identified asBacillus subtilis, Bacillus licheniformis andBacillus cereus. The pH optima for the partially purified enzymes of these organisms were 7.0, 5.5 and 7.5, whilst their temperature optima were 30, 37 and 80°C. There was no significant difference in amylase activities when starch, dextrin, amylopectin, glucose and maltose were used as growth substrates.