VARIACION DE LA DENSIDAD POBLACIONAL DE SMINTHURUS VIRIDIS (L.) (COLLEMBOLA: SMINTHURIDAE) EN LA IX REGION DE LA ARAUCANIA, CHILE

Abstract

The lucerne flea flea S. viridis (L.) is a secondary pest of recent introduction to Chile that has archevied more importance in lucerne in the central-south part of the Country. The study was conducted in the former experimental station Maipo of tile University of La Frontera ill Temuco, ill the agroecological area of the central plain, and in the Regional Research Center INIA Carillanca in the preandean area. The Population variation was studied in both areas Using a standard entomological net every 15 days in tile period from June 1996 to march 1997, as we'll as the eventual natural enemies. Tile results shows in the central plain a low Population from june to august, but an increase LIP to 14,3 individual per m(2) in september. declining strongly from october to march. In the preandean area two peaks occurred, both during the second halfs of october to november with a peak of 15,8 individual per m(2). During the summer months january to february no specimens were collected. The relation between the population variation and the size of lucerne was statistically significance in the central plain, but not ill tile preandean area. The only natural enemic found was the bug Nabis punctipennis (Blanchard) Feeding oil S. viridis, when this species was in summer diapuse.