Effect of “soft-electron” (low-energy electron) treatment on three stored-product insect pests

Developmental stages of three stored-product insect pests viz. Tribolium castaneum (Herbst), Plodia interpunctella (Hübner) and Callosobruchus chinensis (L.) were exposed to “soft electrons”, low-energy electrons. Soft electrons at an acceleration voltage of 170 kV effectively inactivated eggs, larvae and pupae of T. castaneum and P. interpunctella. The adults of T. castaneum and P. interpunctella were inactivated by treatment for 10 min (4.8 kGy) and 15 min (7.2 kGy), respectively. Soft electrons at 170 kV also inactivated the eggs of C. chinensis effectively. The adults of C. chinensis survived a 15 min exposure (7.2 kGy), but were inactivated having lost the ability to walk after a 5 min exposure (2.4 kGy). Soft electrons at 170 kV could not completely inactivate the larvae of C. chinensis inside beans, because the electrons with low penetration did not reach the larvae due to the shield of beans. The movement of T. castaneum larvae exposed to soft electrons was sluggish for several days, and then the larvae died with their hindguts emerged from their posterior ends 17 days after the treatment. DNA comet assay of cells of P. interpunctella larvae indicated that soft electrons at 170 kV damaged DNA in the larvae.