CHEMICAL CONTROL OF Oryzophagus oryzae (COSTA LIMA, 1936) (COLEOPTERA: CURCULIONIDAE) ON FLOODED RICE BY SEED TREATMENT

Abstract

The effect of insecticides applied as seed treatment or granulated in the irrigation water, for the control of larvae of Oryzophagus oryzae (Costa Lima, 1936), was evaluated in a field experiment on flooded rice in conventional system at Embrapa Clima Temperado, Capão do Leão-RS, in the agricultural year 1999/2000. The insecticide thiamethoxam at the doses of 75, 100 and 125 g a.i. 100 kg-1 of seeds and fipronil at the doses of 25, 37.5, 50 and 62.5 g a.i. 100 kg-1 of seeds, when applied to the seeds of rice, reduced the larval population of O. oryzae significantly up to 40 days after flood irrigation, with control efficiency superior to 90%. However, rice seed treatment with thiamethoxam in the dose of 50 g a.i. 100 kg-1 of seeds controlled efficiently rice water weevil larvae only up to 25 days after irrigation. There were no significant differences among treatments in relation to rice yield. It is concluded that both insecticides in the evaluated doses have potential for use in irrigated rice crop for the control of larvae of O. oryzae.