Effects of soil insecticide treatments on maize aphids and aphid predatorsin 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 fir st week after plant emergence. Later, densities in carbofuran-treated plots were significantly higher than in lindane-treated or untreated plots. No d ifferences in the presence of predators on plants were found, but at one fa rm catches of polyphagous ground-foraging predators in pitfall traps were g reater in untreated plots, coinciding with lower aphid density on plants. R esults indicate that the use of carbofuran, in our crop conditions, for con trolling aphids and preventing MDMV was ineffective because aphid colonizat ion and reproduction was not avoided, so allowing virus transmission, and g round-foraging predators were negatively affected. Lindane had no direct ef fect on aphids; and no indirect effects through its impact on predators wer e observed. (C) 1999 Elsevier Science Ltd. All rights reserved.