Population fluctuation of Sternechus subsignatus Boheman (Coleoptera: Curculionidae) at its different development stages associated with soybean crop cycle in Tucumán, Argentina

soybean stalk weevil sternechus subsignatus boheman 1836 (coleoptera: curculionidae) population fluctuation was assessed during a three-year period in northwestern argentina (noa). both population fluctuation of adults, eggs and active larvae on soybean [glycine max (l) merr] host plants, as well as overwintering forms in soil (larvae, pupae and adults), were recorded. s. subsignatus is a univoltine species, so its life cycle is annual and comprises an active phase, when the pest attacks soybean crops and another dormancy phase, when it remains buried in the soil. adults were first observed in the crop from late november up to early march. from then onwards, s. subsignatus development stages where it remained associated with the host plant took place at definite times. the eggs appeared on plants from mid-january to the end of march. larval period lasted from the end of january to the end of april, when larvae jumped onto the ground and buried themselves to spend the winter. pupae were observed towards the end of september, and adults first appeared as october was drawing to a close. a new cicle began, with adults emerging in late november or early december. thus, it was observed that s. subsignatus in the noa region presents a single annual generation.