Evaluation of gamma irradiated essential oils to control stored-grain weevil, Sitophilus zeamais and cockroach, Blattella germanica

Most of the essential oils have insecticidal activity and are alternatives to plant protection and urban pest control. The gamma radiation has been used to control microorganisms and insects in dehydrate herbs, spices, medicinal plants and other materials. This work aimed to evaluate the effect of irradiated essential oils as contact poison on Stored grain, weevil, Sitophilus zeamais and as stomach poison in cockroach, Blattella germanica. The bioassay with B. germanica demonstrated efficiency between 22.0 and 30.0% and between 30.0 and 42.0% respectively, to irradiated essential oils of E. citriodora and E. globulus and they demonstrated too repellency to the nymphs. The gamma radiation promoted changes in essential oils Eucalyptus citriodora and E. globulus and showed increased effectiveness on B. germanica nymphs besides a significative reduction of repellency. Gamma radiation thus interfered on behavior of some essential oils by increasing or reducing activating or inactivating their efficiency to pest control. (author)