Carrizo P.,Zoologia Agricola |
Lopez M.V.,University of Buenos Aires
Idesia | Year: 2010
We analysed the abundance of grasshoppers through forage resources within a farm. Four types were considered: legumes pasture (with and without grazing), grass pasture and soybean. Two operators performed the sampling with net, between November and April (8 lines/plot: 4 in their edges, 4 inside). They were compared in total abundance by means of ANVA (DBA) and Tukey. In a Split-Plot designed location (higher plot) and Operator (small plot) by means of ANVA and DGC. Tettigonüdae dominated in grasses (>90%), and had no relevance (<5%) in soybean. Acrididae (true grasshoppers) dominated (>90%) in soybean and were the most important in legume pasture (>60%) while the Tettigonüdae (30%) was the second. Those with the highest abundance in first generation in legume pasture and grasses were D. punctulatus and a Tettigonüdae. In the second generation, two Gomphocerinae (Acrididae) were the most important. In soybean, the highest abundance in January was because of juvenile forms and in February was because of adults (R. (Dichroplus) bergi, a Gomphocerinae and D. punctulatus). In grasses and legume pastures, the same species trended to dominate as adults and juveniles; although it did not happen in soybean. That Tettigonüdae very abundant in grasses, were also in high numbers in legume pastures, but almost did not appear in soybean. However, if that species would require high levels of forage in legume pasture, it could force the dominant Acridoidea there, to move to the soybean. In edges of plots were detected high densities only related with certain kind of neighbours: a similar resource with high densities or non-removed areas (roads and water canals). When considering all edges with the same plot, this effect was diluted and there was not difference between them and the centre of the plot. Differences between operators were not detected.
Mazzuferi V.E.,Zoologia Agricola |
Maidana A.,Zoologia Agricola |
Fichetti P.,Zoologia Agricola |
Hansen L.G.,Zoologia Agricola |
Avalos D.S.,Zoologia Agricola
AgriScientia | Year: 2011
Aphids may damage plants by sucking plant juices or by transmitting diseases. The aim of this study was to obtain further information about aphid species and their parasitoids in different genotypes of chickpea, calculate the incidence of parasitism and report on fluctuating populations (from aphids and parasitoid) in relation to plant phenology. The study was undertaken during 2006 and 2007 in San Marcos Sierras (Cordoba). Seven lines and two cultivars of chickpea were evaluated. Crop plots were planted following a completely randomized design block with 3 replicates. Every two weeks different developmental stages of aphids and "mummies" found in 10 plants randomly selected from each genotype and block were collected manually. Thirteen species of aphids were identified. In 2006 there was greater abundance and species richness than in 2007. The numerically dominant species were Acyrthosiphon pisum and A. kondoi. Only 5 species colonized the crop. Chañaritos presented the greatest abundance of insects in both years and M60 and M75 genotypes showed the greatest species richness. In both years, aphids were present during the reproductive stage. There were three species of parasitoids and parasitism was estimated at about 35%.