Assemblages of soil nematodes and land use systems in the 
                                                   benchmark si...
Survey of plant‐parasitic nematodes in Benjamin 
                                     Constant, Amazonas Brazil*
         ...
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Assemblages of soil nematodes and land use systems in the benchmark site of amazonas, brazil

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Assemblages of soil nematodes and land use systems in the benchmark site of amazonas, brazil

  1. 1. Assemblages of soil nematodes and land use systems in the  benchmark site of Amazonas, Brazil* CARES,J.E.& ANDRADE, E.P. – Dep. de Fitopatologia, UnB, C.P. 4457, CEP 70910-900, Brasília, DF, BRAZIL cares@unb.br. *Funded by GEF-UNEP, Implemented by TSBF-CIAT INTRODUCTION MATERIALS AND METHODS Soil nematodes are small invertebrates, known as the most In March 2004, 96 composite soil samples had been collected in six abundant metazoan on earth. Assemblages of soil nematodes windows, of three different locations: windows 1‐2, in Guanabara II; 3‐ include five major trophic groups: plant parasites 5, in Nova Aliança; 6, near the town of Benjamin Constant. The (PP), bacteriovores (BF), fungivores (FF), predators (PR) and sampling comprised six major land use systems (lus): 16 samples from omnivores (OM). Regardless functional group, all of them Primary forest (Pf); 06 from Secondary forest (Sf), over ten years; 34 contribute to nutrient cycling and are part of soil food web. With from Short term secondary forest (Ssf), under 10 years; 09 from aid of ecological measurement tools, nematodes have been used Agroforestry system (Agf), with a variety of fruit trees; 19 from Crops as indicators of a variety of natural and anthropic environment (Cr), mainly cassava and bananas; 13 from Pasture (Pa). Spatially, the alterations. sampling points were distributed in a grid with quadrants of 100 x 100 m. Soil samples were collected in the top layer (0‐20 cm). Nematodes OBJETIVE had been extracted from 300cc of soil, by sieving and sugar floatation The objective of this survey was to see the influence of local land‐ procedures, formalin fixed, counted, and glycerin infiltrate. Permanent use systems on the diversity and trophic structure of nematode slide mounts were prepared with 100 nematodes randomly picked for assemblages in Benjamin Conststant, Amazonas, Brazil. generic identification. RESULTS Eighty‐two genera in 36 families were identified. Regardless lus, the communities were dominated by plant parasites. Mean total abundance was higher in Pasture and Secondary forest (Fig. 1), while nematode diversity and trophic diversity were higher in Primary and in Secondary forest, and lower in Pasture (Fig. 2). Relative abundance for each trophic group decreased as follows: PP% (Agf >Ssf>Pa>Pf >Cr>Sf ); FF% (Sf >Pf >Agf >Cr >Ssf >Pa); BF% (Sf >Cr>Pf > Ssf >Agf >Pa); PR% (Pf>Cr >Sf >Agf >Ssf>Pa); OM% (Sf>Pa>Pf>Cr>Ssf>Agf). Regardless land use system plant‐parasitic nematodes were dominant over free living ones (Fig. 3). The ratio FF/BF indicates that decomposition was dominated by fungi, in all lus (Fig. 4). Principal Component Analysis (Fig. 5) indicated pasture apart from the other lus (PC1). Plant‐ Parasitic‐ nematodes, Agroforestry and Young Secondary forest loaded positively on PC2 Axis, while the free living ones grouped in the opposite in the negative side with Primary forest Old secondary forest and crops. The was slight tendency of the omnivores towards pasture. a 0.8 PC2=22% 800 ab 0.7 700 bc 0.6 600 cd 0.5 500 d 0.4 400 d Agroforestry 0.3 300 0.2 200 0.1 Plant parasitic 100 0 Young Sec. Forest 0 Fig. 3. Ratio free living to plant-parasitic nematodes Fig. 1. Mean Total abundance of nematodes 300 cc. soil PC1=52% Old Secondary forest 18 Fungal feeders 16 a 14 6 ab a Pasture ab 12 ab 10 4 b 8 Crops 6 2 4 2 Bacterial feeders 0 0 Eigen  values Predators Omnivores Fig. 4. Ratio fungal feeder to bacterial feeder nematodes Forest Fig. 2. Averages of genus richness of nematodes in 300 cc of soil. CONCLUSIONS Fig. 4. Principal component analysis bi-plot of the distribution of five nematode trophic groups with respect to land use Diversity and trophic structure of assemblages of nematodes changed according to land use. Regardless land use, plant‐parasitic were dominant over free living nemantodes. In all land uses the ratio fungal ACKNOWLEDGMENTS feeders/bacterial feeders indicates that the decomposition was mainly driven by The authors aknowledge BiosBrasil Technicians Elson Gomes de Souza and Andison Abreu Magalhães, and the fungi. Further investigation is needed to find the reasons for the pastures being people of the Communities of Nova Aliança and Guanabara 2, for their major contribution during field work. so different from the other systems as indicated by the nemtode assemblages.
  2. 2. Survey of plant‐parasitic nematodes in Benjamin  Constant, Amazonas Brazil* CARES, J. E.1, SANTOS, J. R. P., ANDRADE , E. P., MOREIRA, F. ARAÚJO, K. P. & SOUZA, E. G. – 1Dep. de  Fitopatologia, UnB, C.P. 4457, CEP 70910‐900, Brasília, DF, BRAZIL  cares@unb.br. *Funded  by GEF‐UNEP, Implemented  by TSBF‐CIAT INTRODUCTION MATERIALS AND METHODS Plant‐parasitic nematodes often lead to crop loss worldwide. In March 2009, In each of the three sampling sites (Guanabara Mainly under conditions of subsistence agriculture these II, Nova Aliança, and Benjamin Constant), 24 soil samples with pathogens go unnoticed, therefore, control measures are not the root content were collected randomly from the rhizosphere applied. of the most frequent cultivated plants, in the depth of zero to 20 cm. Nematodes were extracted from 300 cc of soil and from OBJETIVE the root tissues by sieving and sugar floatation techniques. As one of the activities of the project Conservation and Sustainable Management of Below Ground Biodiversity, a survey was conducted to evaluate occurrence and distribution of plant‐ RESULTS/DISCUSSION parasitic nematodes associated with main agricultural crops in the Plant parasitic nematodes in 11 genera were detected benchmark of BGBD project in Benjamin Constant, AM, Brazil. (Aorolaimus, Boleodorus, Criconemoides, Discocriconemella, Gr acilacus, Helicotylenchus, Meloidogyne, Pratylenchus, Radopholus, Trophotylenchulus, and Xiphinema). Most of them were detected in very low densities (from 1 to 1076 individuals per sample). Important genera of plant‐parasitic nematodes were detected: Meloidogyne (the root‐knot nematode), Pratylenchus (the lesion nematode) and Radopholus (the burrowing nematode). Juveniles of Meloidogyne sp. were detected in only one sample collected in the rhizosphere of cassava in Nova Aliança. Pratylenchus spp. were detected in the three sites associated with different hosts. One species was identified as P. brachyurus. Rhadopholus similis was detected in one sample of soil and roots of banana in Guanabara II. This species is of main concern for that region, since it is a very destructive nematode to bananas and other plant species. In those sites, banana is of major importance as staple food. Banana propagation in their condition relies on taking planting materials from an ongoing field, and this is the most important vehicle of nematode dissemination from field to field, since the pathogen is an endoparasitic living in root and rhizome tissues. Tab. 1. Plant‐parasitic nematodes associated with the main fruit trees and crops annual crops in  Benjamin Constant, Amazonas, Brazil Nematodes Guanabara II Nova Aliança Benjamin Constant Aorolaimus sp. x Boleodorus spp. x x x Criconemoides spp. x x x Discocriconemella spp. x x Gracilacus spp. x x Helicotylenchus spp. x x x Meloidogyne sp. x Pratylenchus brachyurus x x x x – Minor concern Pratylenchus spp. x x x– Medium concern Radopholus similis x Trophotylenchulus sp. x x– Major concern Xiphinema spp. x x x CONCLUSIONS ACKNOWLEDGMENTS Potentially important plant‐parasitic nematodes as Meloidogyne The authors aknowledge BiosBrasil Technician Andison Abreu spp., Pratylenchus spp. and Radopholus similis are associated with main Magalhães, and the people of the Communities of Nova Aliança annual a perennial crops in Benjamin Constant. The burrowing nematode (R. and Guanabara 2, for their major contribution during field work. similis) can put in risk banana production in Benjamin Constant region. None of the nematodes detected was in population levels to bring immediate concern to associated crops.

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