ABSTRACT
The object of this study was to evaluate the effect of the use of phosphine, associated with atmospheres rich in carbon dioxide, on the effective control of Sitophilus zeamais, in all developmental phases, in corn stored at 29°C and 65% relative humidity. Treatments consisted of a combination of controlled atmosphere (21% CO2 and 79% N2) with three phosphine doses (0.25, 0.50 and 0.75g.m-3) and ambient atmosphere with two phosphine doses (0.0 and 1.0 g.m-3), plus three exposure periods (24, 72 and 120h), resulting in 15 treatments. To achieve this a hermetic chamber was built, consisting of a system for the gas injection and exhaustion, a device for gas humidification and another for temperature control. To evaluate the efficiency of the modified atmosphere in all developmental phases of S. zeamais, the number of surviving adult insects was counted. It is concluded that by increasing the exposure period, the efficiency of control is increased, except for the second instar larvae. The effective control (100%) of all developing stages of Sitophilus was achieved with the synthetic atmosphere and 0.50 and 0.75 g.m-3 of phosphine, for an exposition period of 120h.
Key words:
controlled atmospheres; Sitophilus zeamais; stored grain