Interaction between essential oil of Rosmarinus officinalis and gamma radiation against Callosobruchus maculatus

In order to examine possible integration between irradiation and botanical pesticides, combined effects of essential oil from Rosmarinus officinalis L. and gamma radiation were determined on mortality of Callosobruchus maculatus F. (Coleoptera: Bruchidae). Experiments were conducted by pretreatment with essential oil fumigation followed by irradiation and inversely, pretreatment with irradiation followed by essential oil fumigation. The mortality rate was assessed 72 h after last treatment. Integration of gamma radiation and R. officinalis oil enhanced the mortality of C. maculatus compared with control treatments of either irradiation or fumigation alone. Synergistic effects of mortality on 1-2 days old adults of C. maculatus were observed when exposed to combination of gamma radiation and essential oil. It was found that pretreatment with fumigation followed by irradiation was perfectly effective. The study showed that either of the pretreatments could enhance the susceptibility of the pest to the other treatment. Our findings led to a conclusion that the combination of gamma radiation and R. officinalis oil fumigation has a potential for application in integrated management of C. maculatus.