Bioavailability and influence of¹⁴C-carbofuran onEisenia andreiavoidance, growth and reproduction in treated natural tropical soils

Abstract

The bioavailability of carbofuran to the compost worms Eisenia andrei and the influence of its residual amounts on the avoidance, reproduction and growth of this species were studied in two natural tropical soils: a Typic Humaquept (GM) and a Typic Hapludox (LVD), as indicated by the Brazilian environmental authorities for ecotoxicological tests. The worms avoided the soil LVD treated with different doses of carbofuran. The pesticide also affected the production of juvenile specimens in both soils, but cocoon production was reduced only in the GM soil. The earthworms' growth and weight loss were affected by carbofuran (2,2-dimethyl-2,3-dihydro-1-1-benzofuran-7-yl methylcarbamate. CAS number 1563-66-2) only in the LVD and the mortality detected at 56 days of contact with the treated soils was not statistically significant in both of them. Fourteen days after the soil treatment with(14) c-carbofuran, most residues detected in the soils were bound residues (approximately 36% and 30% in the GM and LVD, respectively) and neither mortality nor bioaccumulation was detected in the earthworms, even with absorptions of 13% and 43%, respectively. The LVD soil has lower organic matter content, and the effects of carbofuran on different aspects of the earthworms' life were more pronounced in this soil, most likely due to the higher bioavailability of the pesticide in the soil solution. The results for carbofuran clearly demonstrate that even small quantities of residues do not assure lack of toxicity. They also make evident the necessity of studying the effects of pesticides in natural agricultural soils. Furthermore, as the bound residues and the earthworm contamination are not detected by conventional techniques, they are not taken into account and may be underestimated on environmental risk assessments.

Effect of chlorpyrifos and carbofuran on morphology, behavior and acetylcholinesterase activity of earthworm (Eisenia fetida)

“…Reduction in body surface area by extensive coiling may be seen as strategy of worms to escape exposure to pesticides. The present findings can be justified with the observations by Santos et al (2011) andFerreira et al (2015). Mudiam (2013) stated the decrease in sugar amount in earthworm, Metaphire posthuma exposed to carbofuran-treated soil, which also stresses upon the increased energy demands due to toxicity induced stress.…”

Environmental risk assessment of pesticides in tropical terrestrial ecosystems: Test procedures, current status and future perspectives

“…Similarly, Chelinho et al (2014) noted a lower toxicity of carbofuran in a soil with a higher moisture content and attributed this to increased degradation and greater dilution of the pesticide in the soil pore water. In another study with carbofuran, Ferreira et al (2015) studied the bioavailability and the effects of radio-labelled carbofuran on the avoidance behavior, growth and reproduction of Eisenia andrei in two natural tropical soils, covering almost the same range of soil properties as in the previous study. These authors explained the different toxicity with the lower organic matter (OM) content in the soil where the worms were more affected.…”

Uso de testes de fuga com minhocas Eisenia andrei e Eisenia fetida para identificação da toxidade de agrotóxicos no Brasil: Uma breve revisão da literatura

“…O Carbendazim e Lambda-Cialotrina apresentaram respostas significativas de fuga a partir das menores concentrações testadas, 1,0 mg/kg e 0,32 mg/kg, respectivamente (GARCIA et al, 2008). Abamectina e Carbendazim foram avaliados por dois estudos cada um e todos relataram comportamento de fuga para esses ingredientes ativos (BUCH et al, 2010;BUCH et al, 2013;FERREIRA, PAPINI;ANDRÉA, 2015;GARCIA et al, 2008;. Os demais ingredientes ativos foram avaliados por um único estudo.…”