Effects of soil insecticide treatments on maize aphids and aphid predators in Catalonia

The effect on maize aphids and aphid predators of granular formulations of carbofuran and lindane applied at sowing was evaluated from plant emergence to flowering in a three-year study at two commercial farms. Plots treated with carbofuran showed lower total aphid and alate densities during the first week after plant emergence. Later, densities in carbofuran-treated plots were significantly higher than in lindane-treated or untreated plots. No differences in the presence of predators on plants were found, but at one farm catches of polyphagous ground-foraging predators in pitfall traps were greater in untreated plots, coinciding with lower aphid density on plants. Results indicate that the use of carbofuran, in our crop conditions, for controlling aphids and preventing MDMV was ineffective because aphid colonization and reproduction was not avoided, so allowing virus transmission, and ground-foraging predators were negatively affected. Lindane had no direct effect on aphids; and no indirect effects through its impact on predators were observed. (C) 1999 Elsevier Science Ltd. All rights reserved.