Comparação entre doses de Alil isotiocianato e a solução de formaldeído na extração de minhocas

Abstract

A solução de formaldeído é o extrator mais utilizado na amostragem de minhocas, mesmo com riscos potenciais aos seres humanos e ao meio ambiente. O reagente Alil isotiocianato (AITC), fitocomplexo da mostarda sintetizado em laboratório, foi testado em condições de clima temperado. Entretanto, não existem dados de sua utilização no Brasil. Esta pesquisa teve por objetivo avaliar a eficácia do reagente AITC em relação à solução de formaldeído 2,2 g L -1 na extração de minhocas, sob diferentes sistemas de uso do solo no início do verão. O experimento foi realizado em uma fazenda localizada no Município de Castro (PR), no período de 16 a 23 de dezembro de 2003. Os três sistemas selecionados foram: 1) um talhão de plantio direto também utilizado para pastejo; 2) pastagem perene; e 3) mata subtropical perenifólia. No talhão de plantio direto, o AITC 50 mg L -1 resultou em maior eficiência na obtenção da densidade populacional (144 indivíduos m -2 ) e biomassa (26,3 g m -2 ) do que a solução de formaldeído (123,4 ind m -2 e 21,7 g m -2 respectivamente). Na pastagem perene e na mata, a solução de formaldeído foi de maior eficácia. Foram encontradas minhocas das famílias Megascolecidae, Octochaetidae e Lumbricidae. O AITC é considerado promissor na determinação da densidade populacional e biomassa em sistemas de plantio direto. Os resultados variam com a concentração da solução extratora e o sistema avaliado.Palavras-chave: minhoca, extração, formaldeído, AITC, densidade, biomassa. ABSTRACT DETERMINATION OF ALLYL ISOTHIOCYANATE CONCENTRATION TO SUBSTITUTE FORMALDEHYDE FOR SAMPLING EARTHWORMSFormaldehyde solution is the commonest substance used in the world to extract earthworm from soil despite of its harmful potential to humans and for the environment. Allyl isothiocyanate (AITC), a mustard oil, was tested under temperate climate condition. There is no record of its use on Brazilian soils. This research was established to evaluate the performance of different AITC rates compared to formaldehyde, under different soil uses at early summer. The experiment was established in a farm located at Castro county, Paraná State, Brazil, from 16 to 23 of December, 2003. Three ecosystems were selected: 1) no-tillage field used for crop-livestock; 2) permanent grassing pasture; and 3) araucaria native forest. In no-tillage, AITC 50 mg L -1 presented the highest density (144 individuals m -2 ), followed by formaldehyde (123.4 m -2 ), AITC 100 (115.4 m -2 ) and AITC 150 (76.1 m -2 ). For biomass, AITC 50, 100 and 150 mg L -1 extraction were superior to formaldehyde (21.7 g m -2 ). In permanent pasture, formadehyde gave three and two fold more density and biomass, respectively than the other treatments. In the forest, formaldehyde was superior to the AITC rates tested. However, AITC 50 and 100 mg L -1 were equivalent to formaldehyde for biomass. Megascolecidae, Octochaetidae and Lumbricidae were the three earthworm' families found in the experimental area. The use of AITC is prospective to determine density and biomass under no-till syst...

Recommendations for assessing earthworm populations in Brazilian ecosystems

“…Over 150 studies on earthworm populations or soil macrofauna in general, including earthworms, were found. Different methods were used to sample earthworms and to make them rise to the soil surface (Peixoto & Marochi, 1996;Römbke et al, 1999;Ressetti, 2006;Ressetti et al, 2008;Steffen et al, 2013), including chemical solutions, such as diluted formaldehyde, mustard or onion extracts, or their main chemical components, e.g., Allyl isothiocyanate (AITC) (Zaborski, 2003;Pelosi et al, 2009). Although, in some locations, some species of earthwormsparticularly epigeics, epi-endogeics, or anecicsmay be better sampled by chemical extraction or by combining both hand-sorting and chemical extraction (Römbke et al, 1999;Römbke, 2007), only handsorting studies were selected, because this was the most common method used and would allow a more thorough comparison between studies.…”

“…bras., Brasília, v.55, e01006, 2020 DOI: 10.1590/S1678-3921.pab2020.v55.01006 as the recommended chemical extractant in the latest ISO norm (ISO, 2018), due the possible carcinogenic properties of formalin. However, only one study has tested the efficiency of AITC in Brazil (Ressetti et al, 2008), which was higher than formalin in cropping systems, but lower in pasture and native forest. Therefore, further research is needed to evaluate the adoption of AITC as the recommended chemical extractant in the country.…”

Earthworms in Brazilian no‐tillage agriculture: Current status and future challenges

“…1, Bartz, Brown, Orso, Mafra, and Baretta (2014); 2, Bartz, Brown, da Rosa, et al (2014); 3, Bartz et al (2013); 4, Brown et al (2003); 5, Brown et al (2004); 6, Brown and James (2007); 7, Gorte (2016); 8, Krabbe, Driemeyer, Antoniolli, and Giracca (1993); 9, Peixoto and Marochi (1996); 10, Ressetti, Dionísio, and Motta (2008); 11, Rodrigues, Aquino, Pereira, Correia, and Guerra (2004); 12, Santos et al (2018); 13, Steffen (2012); 14, Tanck, Santos, and Dionísio (2000); 15, Voss (1986). …”