Moiana L.D.,Institute Investigacao Agraria Of Mocambique |
Filho P.S.V.,State University of Maringa |
Goncalves-Vidigal M.C.,State University of Maringa |
de Carvalho L.P.,Embrapa Algodao
Australian Journal of Crop Science | Year: 2015
To better understand the genetic diversity of the cultivated upland cotton (Gossypium hirsutum L.) and its structure at the molecular level, microsatellite markers were used. The objective of this study was to evaluate genetic diversity and population structure in tetraploid cotton (Gossypium hirsutum L. race latifolium H.). Twenty cultivars and inbred lines from Embrapa Cotton Breeding Program, Brazil, were analyzed. From a total of 33 microsatellite (SSR) markers, twenty seven markers revealed 91 polymorphic SSR alleles. Two sub-populations were identified applying different methods (The Bayesian analysis, Principal Coordinates Analysis and Neighbor Joining Tree). Most of the cultivars belongs to Embrapa Cotton Breeding Program were allocated in sub-population I. The Fst index indicated moderate genetic variability among the studied cultivars. In general, Embrapa cotton cultivars were the most dissimilar to GIBANGA and IMA CD05-8221 cultivars. The dissimilarity index ranged from 0.13 to 0.73 and the lowest genetic divergence was observed between BRS PRECOCE and BRS 286 genotypes. Combination of Embrapa cotton cultivars, GIBANGA and IMA CD-05 8221 is recommended for obtaining superior segregation in order to improve yield.
Malia H.A.E.,Federal University of Vicosa |
Malia H.A.E.,Institute Investigacao Agraria Of Mocambique |
Rosi-Denadai C.A.,Federal University of Vicosa |
Cardoso D.G.,Federal University of Vicosa |
Guedes R.N.C.,Federal University of Vicosa
Journal of Pest Science | Year: 2015
The role of behavior in insecticide susceptibility is broadly recognized, in addition to the physiological effects of insecticides. Curiously, the recognition of the importance of behavior does not extend to the control by physical agents, like inert dusts such as diatomaceous earth (DE). Furthermore, behavioral traits are typically regarded as isolated traits and not as suite of traits simultaneously expressed in individual organisms, referred to as personality (or individuality). Because the set of behavioral traits of an individual may play a role in susceptibility to physical control agents, such as DE, a set of six behavioral traits encompassing three personality dimensions (i.e., activity, boldness/shyness, and exploration/avoidance), were assessed in six populations of the maize weevil Sitophilus zeamais. The (average) behavioral types varied among populations (Wilks´ lambda = 0.09, F45/674 = 10.72, P < 0.001), as did the susceptibility to DE (χ2 = 11.0, df = 5, P = 0.05), with median survival times (95 % CL) ranging from 144.00 (119.69–168.31) h to 216.00 (179.10–252.90) h. These different behavioral types were not recognized when individual-based analysis was performed, although the individual hierarchical level represented over 63 % of the variance in the behavioral traits. Weevil activity was successfully used to describe survival time and, therefore, the susceptibility to diatomaceous earth, but the population-based response was crudely oversimplified. Therefore, to disregard the inter-individual behavioral variation, even when simple behavioral traits suitably describe the susceptibility to DE, in favor of interpopulation variation is temerary and may lead to management shortcomings. © 2015 Springer-Verlag Berlin Heidelberg
Makanda I.,University of KwaZulu - Natal |
Tongoona P.,University of KwaZulu - Natal |
Derera J.,University of KwaZulu - Natal |
Sibiya J.,University of KwaZulu - Natal |
Fato P.,Institute Investigacao Agraria Of Mocambique
Field Crops Research | Year: 2010
Sorghum grain production in sub-Saharan Africa is constrained by the fact that farmers' choice of improved varieties is limited. Hybrid cultivars have been shown to be more productive for grain than pure line and landrace varieties hence their development can enhance productivity and food security. This study was, therefore, conducted to determine combining ability of 18 sorghum lines, the level of heterosis and cultivar superiority of experimental hybrids in tropical lowland and mid-altitude environments. Eight cytoplasmic male-sterile lines were crossed with 10 male-fertile lines in accordance with the North Carolina II mating scheme to generate 80 experimental hybrids. The hybrids, parents and two standard check varieties were evaluated in replicated row-column α-designs across six environments in Mozambique, South Africa and Zimbabwe. Cultivar superiority was assessed using the cultivar superiority index (Pi). Results indicated significant (P ≤ 0.05) differences among genotypes for both grain yield potential and secondary traits. Hybrids were predominant in the top 20 ranking for grain yield, and displayed up to 285% standard heterosis. Overall hybrid mean yield was significantly higher than that of parents and standard check varieties, which was attributed to high levels of average heterosis and standard heterosis, respectively. Grain yield data were positively and significantly correlated with head length and number of leaves plant-1, suggesting an improvement in grain yield potential as the number of leaves and head size increase. General combining ability (GCA) and specific combining ability (SCA) effects were significant (P ≤ 0.05) for all traits, implying that both additive and non-additive gene effects were important. Both GCA and SCA effects significantly interacted with site effects demonstrating the need for multi-location testing of potential cultivars. However, the top grain yielders were generally stable across environments. Parents ICSV700, ICSR165, S35, IMDP97, ICSA4, ICSA724, and ICSA26 with positive and significant GCA effects, which also revealed significant SCA effects in crosses for grain yield were identified as potential materials for inclusion in the hybrid breeding programme. © 2009 Elsevier B.V. All rights reserved.
Cala A.C.,Institute Investigacao Agraria Of Mocambique |
Ferreira J.F.S.,U.S. Department of Agriculture |
Chagas A.C.S.,Brazilian Agricultural Research Corporation |
Gonzalez J.M.,U.S. Department of Agriculture |
And 6 more authors.
Parasitology Research | Year: 2014
There is no effective natural alternative control for gastrointestinal nematodes (GIN) of small ruminants, with Haemonchus contortus being the most economically important GIN. Despite frequent reports of multidrug-resistant GIN, there is no new commercial anthelmintic to substitute failing ones. Although trematocidal activity of artemisinin analogs has been reported in sheep, neither artemisinin nor its plant source (Artemisia annua) has been evaluated for anthelmintic activity in ruminants. This study evaluated the anthelmintic activity of A. annua crude extracts in vitro and compared the most effective extract with artemisinin in sheep naturally infected with H. contortus. A. annua leaves extracted with water, aqueous 0.1 % sodium bicarbonate, dichloromethane, and ethanol were evaluated in vitro by the egg hatch test (EHT) and with the bicarbonate extract only for the larval development test (LDT) using H. contortus. The A. annua water, sodium bicarbonate (SBE), ethanol, and dichloromethane extracts tested in vitro contained 0.3, 0.6, 4.4, and 9.8 % of artemisinin, respectively. The sodium bicarbonate extract resulted in the lowest LC99 in the EHT (1.27 μg/mL) and in a LC99 of 23.8 μg/mL in the LDT. Following in vitro results, the SBE (2 g/kg body weight (BW)) and artemisinin (100 mg/kg BW) were evaluated as a single oral dose in naturally infected Santa Inês sheep. Speciation from stool cultures established that 84-91 % of GIN were H. contortus, 8.4-15.6 % were Trichostrongylus sp., and 0.3-0.7 % were Oesophagostomum sp. Packed-cell volume and eggs per gram (EPG) of feces were used to test treatment efficacy. The SBE tested in vivo contained no artemisinin, but had a high antioxidant capacity of 2,295 μmol of Trolox equivalents/g. Sheep dosed with artemisinin had maximum feces concentrations 24 h after treatment (126.5 μg/g artemisinin), which sharply decreased at 36 h. By day 15, only levamisole-treated sheep had a significant decrease of 97 % in EPG. Artemisinin-treated and SBE-treated sheep had nonsignificant EPG reductions of 28 and 19 %, respectively, while sheep in infected/untreated group had an average EPG increase of 95 %. Sheep treated with artemisinin and A. annua SBE maintained blood hematocrits throughout the experiment, while untreated/infected controls had a significant reduction in hematocrit. This is the first time oral dose of artemisinin and an aqueous extract of A. annua are evaluated as anthelmintic in sheep. Although oral dose of artemisinin and SBE, at single doses, were ineffective natural anthelmintics, artemisinin analogs with better bioavailability than artemisinin should be tested in vivo, through different routes and in multiple doses. The maintenance of hematocrit provided by artemisinin and A. annua extract and the high antioxidant capacity of the latter suggest that they could be combined with commercial anthelmintics to improve the well-being of infected animals and to evaluate potential synergism. © 2014 Springer-Verlag.
Food supplements and toxic bait used to manage the coffee leafminer and its natural enemies in a conventional crop system [Suplementos alimentares e isca tóxica no manejo do bicho-mineiro e de seus inimigos naturais]
Ecoli C.C.,Institute Investigacao Agraria Of Mocambique |
Moraes J.C.,Federal University of Lavras |
Vilela M.,Federal University of Lavras
Coffee Science | Year: 2010
This work assessed the effect of food supplements on the population of the coffee leaf-miner Leucoptera coffeella (Guérin-Mèneville & Perrottet) (Lepidoptera: Lyonetiidae) and its natural enemies. The experiment was set up at the Federal University of Lavras (UFLA) in a five-year-old dense, conventional cv. Rubi crop planted in a 2.0 × 0.6 m spacing. The experimental design was in randomized blocks with six treatments and four replications. The treatments were: beer yeast and honey (1:1) at 20%, molasses at 10%, hydrolyzed protein at 2%, hydrolyzed protein at 2% with cartap (20 g a.i./ha) (toxic bait), cartap (20 g a.i./ha) and control (water). The features assessed were: percentage of mined leaves, percentage of mined leaves preyed on by wasps, number of live coffee leaf-miner caterpillars, number of pupae formed per sixty leaves and the percentage of parasitism. The most important parasitoids were Orgilus niger, Centistidea striata, Stiropius reticulatus and Horismenus sp. After application of the toxic bait and cartap insecticide treatments, a reduction in both the total parasite population and per parasitoid species was observed. The results suggest further studies for recommending food supplements as a pest management tactic in coffee crops. Toxic bait used to manage the coffee leaf-miner affected negatively the population of its natural enemies.