Effects of glyphosate on cellulose decomposition in two soils

Use of genetically modified crops and pesticides in Brazil: growing hazards

Abstract Genetically modified (GM) crops were officially authorized in Brazil in 2003. In this documentary study, we aimed to identify possible changes in the patterns of pesticide use after the adoption of this technology over a span of 13 years (2000 to 2012). The following variables were analyzed: Pesticide use (kg), Pesticide use per capita (kg/inhab), Pesticide and herbicide use per area (kg/ha) and productivity (kg/ha). Contrary to the initial expectations of decreasing pesticide use following the adoption of GM crops, overall pesticide use in Brazil increased 1.6-fold between the years 2000 and 2012. During the same period, pesticide use for soybean increased 3-fold. This study shows that the adoption of GM crops in Brazil has led to an increase in pesticide use with possible increases in environmental and human exposure and associated negative impacts.

Fungal utilization of organophosphate pesticides and their degradation by Aspergillus flavus and A. sydowii in soil

Fungal species were isolated which utilize organophosphate pesticides, viz. phosphorothioic (pirimiphos-methyl and pyrazophos), phosphorodithioic (dimethoate and malathion), phosphonic (lancer) and phosphoric (profenfos) acid derivatives. Pesticide degradation was studied in vitro and in vivo (soil). Aspergillus flavus, A. fumigatus, A. niger, A. sydowii, A. terreus, Emericella nidulans, Fusarium oxysporum and Penicillium chrysogenum were isolated from pesticide-treated wheat straw. The number of A. sydowii colonies was significantly promoted by 1 mmol/L pirimiphos-methyl, pyrazophos, lancer, dimethoate and malathion when used as phosphorus sources and by pirimiphos-methyl and pyrazophos when used as carbon sources. The number of A. flavus colonies increased with 0.5 mmol/L lancer and malathion used as the only carbon sources. A. sydowii, A. niger, A. flavus, E. nidulans and F. oxysporum grew on, and utilized, 5 pesticides as phosphorus source and showed more than 50% mass growth. A. sydowii, A. flavus and F. oxysporum phosphatase hydrolyzed the pesticides suggesting that these species are important pesticide degraders. A. sydowii produced higher amounts of the phosphatase than A. flavus and F. oxysporum. The enzyme was highly active against pyrazophos, lancer and malathion used as the only sources of organic phosphate. A. flavus and A. sydowii phosphatases efficiently hydrolyzed pesticides at 300 ppm in soil, the degradation at 1000 ppm was lower. Mineralization of 1000 ppm pesticides in soil amended with wheat straw was higher than in nonamended soil. All added pesticides except profenfos were degraded within 3 weeks. Lyophilized adapted biomass of A. flavus and A. sydowii could thus be used for field biodegradation of these pesticides.