Efficacy of soft-electron (low-energy electron) treatment for disinfestation of brown rice containing different ages of the maize weevil, Sitophilus zeamais Motschulsky

Soft electrons (low-energy electrons) have been reported to effectively disinfest grains contaminated with stored-product insects. In this study, brown rice grains infested with different ages of the maize weevil, Sitophilus zeamais Motschulsky, were exposed to soft electrons. Soft electrons at an acceleration voltage of 170 kV effectively inactivated eggs, old larvae and pupae of the maize weevil, but could not completely inactivate young larvae. The locations of young larvae in rice grains were specified by magnetic resonance microimaging. Most of the larvae resided at the periphery of the grains while only a few at the center, which were assumed to get out of inactivation. This indicated that soft electrons with low penetration capacity could reach the most of weevil larvae in grains. Combination of soft-electron treatment and short time-low-dose phosphine fumigation achieved high mortality rate of S. zeamais.