Insecticidal effect of Dittrichia viscosa lyophilized epicuticular material against four major stored-product beetle species on wheat

We examined the insecticidal effect of lyophilized epicuticular material of the ruderal species Dittrichia viscosa in four major stored-product beetle species. Furthermore, the potential of this material in progeny production suppression was also evaluated. The water-soluble extract was derived from plants that had been harvested in September 2016, through freeze-drying, in order to create a fine powder formulation. In our bioassays, the powder was applied in four doses on wheat: 0 (control), 1000, 3000 and 5000 ppm and mortality of the exposed individuals was measured after 1, 3, 7, 14 and 21 days of exposure, while progeny production capacity was recorded 65 days later. Among the species tested, Oryzaephilus surinamensis was found to be the most susceptible, followed by Tribolium confusum and Sitophilus oryzae, while Rhyzopertha dominica was not practically affected. Progeny production was particularly reduced for all species relative to the controls. Indicatively, for O. surinamensis, at the highest dose rate, there were only 0.2 adults per vial, while the respective figures for the control exceeded 40 adults per vial. To our knowledge, this study is the first that examined the insecticidal effect of epicuticular material of D. viscosa for the control of stored-grain insect species. Additional experimentation is required to indicate the rationale of using this natural resource-based material under a non-chemical control strategy at the post-harvest stages of agricultural commodities. © 2020 Elsevier Lt