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Tiago P.V.,Federal University of Pernambuco | Medeiros L.V.,Agronomical Institute of Pernambuco | Carneiro Leao M.P.,Federal University of Pernambuco | Santos A.C.D.S.,Federal University of Pernambuco | And 2 more authors.
Biocontrol Science and Technology | Year: 2016

Isolates of Fusarium obtained from Dactylopius opuntiae (Cockerell) (Hemiptera: Dactylopiidae) demonstrated potential as biological control agents against that same insect, which is a pest on Opuntia ficus-indica L Miller. The isolates belong to two species complexes: Fusarium incarnatum-equiseti (FIESC – five species) and Fusarium fujikuroi (FFSC – one species). Twenty-eight isolates of these fungi were characterised using seven Inter Simple Sequence Repeats (ISSR) primers. The UBC841 primer differentiated all the FIESC isolates studied and the single isolate of Fusarium pseudocircinatum O’Donnell & Nirenberg at a level greater than 90% similarity for the fragment sizes. The results indicated high genetic variability among those isolates, an important characteristic for biological control, increasing the chances of finding efficient fungi for insect control. The ISSR markers UBC834 and UBC841 were found to be efficient for characterising and differentiating (DNA fingerprinting) those fungi, and could be used in field monitoring. © 2016 Informa UK Limited, trading as Taylor & Francis Group.

da Silva Santos A.C.,Federal University of Pernambuco | Oliveira R.L.S.,Federal University of Pernambuco | da Costa A.F.,Agronomical Institute of Pernambuco | Tiago P.V.,Federal University of Pernambuco | de Oliveira N.T.,Federal University of Pernambuco
Journal of Pest Science | Year: 2015

In northeast Brazil, the cactus Opuntia ficus-indica is a key species for feeding livestock. However, productivity has been reduced by the cochineal scale Dactylopius opuntiae. Fusarium incarnatum-equiseti species complex (FIESC) strains obtained from D. opuntiae show potential as biological control agents. Furthermore, the insecticidal action of entomopathogenic fungi can be enhanced when used in conjunction with insecticides of plant origin. This study aimed to verify the insecticidal action of extracts of Ricinus communis and Poincianella pyramidalis separately and in combination with FIESC isolates against D. opuntiae. We evaluated the compatibility of FIESC 20-b isolates with aqueous and hydroethanolic extracts of R. communis and P. pyramidalis at w/v concentrations of 5, 10 and 20 %. The treatments used in the four bioassays against D. opuntiae were selected using the Biological Index model. The aqueous and hydroethanolic extracts of R. communis and P. pyramidalis were compatible with some FIESC 20-b isolates. The corrected mortality values at different bioassays ranged from 61.23 to 100 %. The insecticide action resulting from the combination of the URM6778 isolate with aqueous extract of R. communis was the highest, producing 100 % mortality on D. opuntiae. Our results indicate FIESC 20-b isolates and extracts of R. communis and P. pyramidalis are promising control agents for D. opuntiae, a low-cost technology and environmentally friendly. © 2015 Springer-Verlag Berlin Heidelberg

Moraes N.D.J.,Federal University of Piauí | Costa Neto V.P.D.,Federal University of Piauí | Araujo A.S.F.D.,Federal University of Piauí | Figueiredo M.D.V.B.,Agronomical Institute of Pernambuco | And 2 more authors.
European Journal of Soil Biology | Year: 2016

Oxidative stress can strongly affect biological nitrogen fixation (BNF) in nodules; therefore, the antioxidant system in nodules works to reduce the damage caused by the deleterious effects of oxidizing compounds and maintain adequate BNF. In this context, the objective of this work was to evaluate variables related to BNF and oxidative metabolism in the nodules of cowpea inoculated with Bradyrhizobium sp. and grown in soils subjected to different levels of composted tannery sludge amendment. A randomized block design was used with a 4 × 2 factorial scheme, involving four doses of composted tannery sludge (0, 5, 10, and 20 t ha−1) for uninoculated cowpea and cowpea inoculated with Bradyrhizobium sp. The cowpea inoculated with Bradyrhizobium sp. showed a better growth response than the cowpea inoculated with native rhizobia. Increases in the number of nodules, nodule dry mass, nitrogen fixation efficiency and nitrogen content were recorded in the cowpea inoculated with Bradyrhizobium sp. grown in soils with composted tannery sludge. The cowpea nodules colonized by Bradyrhizobium sp. showed lower hydrogen peroxide levels, while leghemoglobin was maintained at the highest levels. The catalase and phenol peroxidase enzymes were positively modulated in the nodules of the cowpea inoculated with Bradyrhizobium sp. We conclude that the presence of composted tannery sludge affects the establishment and development of the symbiosis between rhizobia and cowpea, mainly between native soil rhizobia and cowpea. When cowpea was inoculated with Bradyrhizobium sp., it was concluded that these plants were able to maintain better plant growth and nitrogen capture and lower oxidative stress in their nodules. Thus, inoculation with Bradyrhizobium sp. could be a useful tool for minimizing the deleterious effects of exposing plants to composted tannery sludge and for ensuring plant growth and productivity. © 2016 Elsevier Masson SAS

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