An Evaluation of the Use of Sulfur Dioxide in Fumigant Mixtures for Grain Treatment1

Abstract

The use of sulfur dioxide in various liquid fumigant mixtures for the treatment of grain was studied under laboratory conditions. By means of insecticidal evaluation and mass spectrometry analyses or interstitial air samples it was shown that SO2 was highly sorbed and/or reacted in grain. Under the conditions of these tests where the fumigant mixtures were applied to the surface of the grain mass and the grain was contained in an essentially leakproof chamber, SO2 did not have an appreciable penetration effect below the surface of the grain. This combination of properties restricts the usefulness of SO2 in grain fumigant mixtures to grain nearest the point of application of the fumigant, and even these uses are temporary in nature. Under these conditions sulfur dioxide would temporarily make safer the initial use of flammable grain fumigants, mask the musty odor of spoiled grain until fumigant vapors are aired, and enhance the kill of insects on the surface areas of grain immediately after application. The use of SO2 in grain fumigant mixtures did not appreciably affect, residual insect kill, or the moisture content of the grain, eliminate musty odor in grain, cool the grain mass or make safer the use of flammable CS2-containing grain fumigants which penetrate the major portions of the grain. New insecticidal data on the fumigation effect of SO2 using various exposure periods (5, 1 and 0.5 hours) in space at 80[degree]F are given for the black carpet beetle larva (Attagenus piceus), confused flour beetle adult and egg (Tribolium confusum), and granary weevil adult (Stiophilus granarius).