Data/hora: 05/06/2024 06:45:00

Biblioteca(s): | Embrapa Soja.
Data corrente: | 21/08/2008
Data da última atualização: | 06/04/2009
Autoria: | MARTINS, P. T.; NUNES, D. H.; PASINI, A.; MOTTE, B.; SANTOS, A. A. dos; SILVA, S. H. da; BROWN, G. G.
Título: | Efficiency of electroshocking and formol extraction of earthworms compared to handsorting in agricultural and natural ecosystems near Londrina, Brazil.
Ano de publicação: | 2006
Fonte/Imprenta: | In: International Symposium on Earthworm Ecology, 8., 2006, Kraków. Abstracts... Kraków: Jagiellonian University, 2006. p. 76.
Idioma: | Inglês
Conteúdo: | Sampling of earthworms is generally a labor intensive and time-consuming activity and means of reducing the time and effort necessary to sample earthworm populations are always welcome. Therefore, in the present study, we compared the efficiency of two "quicker" and "easier" alternatives (electro-shocking and dilute-formalin expulsion) in relation to the traditional hand-sorting method. Sampling was performed in four ecosystems: 1) Native forest (secondary vegetation); 2) edge of a cattail marsh; 3) sorghum croppìng (after harvest); and 4) a >10 yr old Cynodon spp. pasture grazed by horses. Electro-shocking (Thielemann octet method) was performed over an area of approximately 0.4 m2 for 20 min and immediately thereafter, earthworms were handsorted from 0.16 m2 soil monoliths, to a depth of 30 cm, directly underneath the electro-shocked area. Formalin (0.5%) was applied to a 1 m2 area, 5-m away, and the surfacing earthworms collected. Eight samples were taken in the forest and the marsh and 5 samples were taken in the agroecosystems. Earthworms were killed in alcohol (30%) and then fixed in formalin. All individuals collected with each method were counted (separately into age classes), weighed and identified to species level (when possible). Earthworm diversity was always higher with the handsorting method (forest = 8 spp., crop system = 6 spp., swamp = 3 spp., pasture = 2 spp.). Formol and electro-shocking yielded at most 3 species only, generally the fastermoving epigeics and poly-humic endogeics. Amynthas gracilis and Urobenus brasiliensis predominated in the forest, Pontoscolex corethrurus dominated in the marsh and various Dichogaster spp. dominated in the agroecosystems. Earthworm abundance was highest in the cropping system, followed by the forest, swamp and pasture. Efficiency of the sample methods depended on the ecosystem, the species and the measurement in question. At all sites, electro-shocking yielded the fewest earthworms, and the extraction efficiency, was generally low for the total earthworm population: from 0% in the pasture, where the soil was compact and drier, to around 20-30% in the remaining ecosystems. Formalin expulsion was also less efficient than handsorting (10-25%), except in the forest, where it yielded 5 times as many earthworms, primarily due to its efficient sampling of Amynthas and Urobenus spp. Electro-shocking and formalin appear to be interesting methods to sample mostly large, surface-active earthworms, whereas handsorting appears to be better suited for smaller, mostly endogeic earthworm species. Ideally, a combination of both methods should be attempted, to adequately sample both large and faster moving earthworms often missed by handsorting, and smaller, endogeic earthworms, not adequately sampled with formol or electricity.
Categoria do assunto: | --
Registro original: | Embrapa Soja (CNPSO)
Exemplares: | CNPSO - (28431-1) - UPC - SP - -- - 11491 -  - 11491 - DIS