Soybean [(Glycine max (L.) Merrill] commercial fields, maintained under a no-till system, were sampled during the crop seasons 1990/91 and 1996/97, in Cruz Alta and Júlio de Castilhos, Rio Grande do Sul State, to determine the distribution of eggs, larvae and adults of Sternechus subsignatus Boheman (Coleoptera : Curculionidae). Soybean plants and soil were examined at different time schedules. Eggs and larvae were recorded in main stems, lateral branches and leaf petioles, divided into the upper third, medium and lower third of soybean plants. Eggs (87%), and larvae (79%) were mainly observed in the main stem and in the medium plant sections (87% and 78%, respectively). Larval movement was not observed because larvae remained inside the galls, in the same area where the eggs were laid. Adults were located in different places depending on the sampling time. At night, adults were observed to move to the upper third of the plant and, during the day, down to the lower third of the plant and to the soil. The insects are normally concealed during their pre- and post- embryonic stage throughout most of the day.
Insecta; Curculionidae; ecology; behavior; spatial distribution
