Effectiveness of Reduced Rates of Insecticides for the Control of Melanotus communis (Coleoptera: Elateridae) in Sugarcane

Nicholas A. Larsen, Gregg S. Nuessly


Wireworms (larval Elateridae) are perennial pests of newly planted sugarcane causing stand loss directly by damaging growing points and indirectly by introducing disease. Two organophosphate insecticides, phorate and ethoprop, are currently labeled for controlling wireworms in sugar cane. In the first experiment, 4 rates of phorate (100, 87.5, 75, and 62.5% of the current maximum field rate) were used in 2 different types of soil: Dania Muck and Immokalee Fine Sand. In the second experiment, 4 rates of phorate and ethoprop (100, 75, 50, and 25% of current maximum field rates) were used in a Lauderhill Muck soil. A no-treatment and a wireworm-free treatment were used as controls in both experiments. The effect of the insecticide was evaluated in simulated field experiments conducted in 18.9-L (5-gallon) buckets filled with soil and artificially infested with 10 wireworms (Melanotus communis (Gyllenhall), Coleoptera: Elateridae) per bucket. After 60 d, the contents of the buckets were emptied to evaluate damage to the plant and count the surviving wireworms. Insecticides resulted in fewer live wireworms and reduced damage to sugarcane shoots, roots, and seed pieces compared to the no-treatment control. In the first experiment, phorate proved to be very effective at controlling wireworms even at the 62.5% rate. Phorate was more effective in the Immokalee Fine Sand than in the Dania Muck. In the second experiment, phorate was found to be more effective at reducing stand loss and wireworm numbers than ethoprop.Translation by the authors.

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