Effects of carbofuran and carbaryl on the growth of a green alga and two cyanobacteria isolated from a rice soil

Abstract

Two methylcarbamate insecticides, carbofuran and carbaryl, were assessed for their effects on a green unicellular alga, Scenedesmus bijugatus, and two cyanobacteria, Synechococcus elongatus and Nostoc linckia, all isolated from a rice soil. In laboratory studies, both insecticides up to 20 μg ml −1 concentration significantly increased the cell number of S. bijugatus. Synechococcus elongatus was highly sensitive, 5 μg ml −1 of each chemical being lethal. Concentrations, up to 20 or 50 μg ml −1, of the two insecticides initially increased chlorophyll a in N. linckia significantly, which again led to a subsequent inhibition. In general, carbaryl was more toxic than carbofuran to all the test organisms.