Comparison of Susceptibility of Three Stored-Product Insects to Gaseous Ozone

Stored product insects cause millions of dollars of losses annually to stored durable commodities such as grain, grain-based products, legumes, dried fruits and nuts and spices.  The cigarette beetle, Lasioderma serricorne, the drugstore beetle, Stegobium paniceum and merchant grain beetle Oryzaephilus mercator are serious stored products beetles, cosmopolitan in distribution and pervasive and common pests found in United States.  Phosphine, a fumigant commonly used to control these insects is resulting control failures due to insects developing resistance to the phosphine.  Ozone is a toxic gas, can kill insects effectively, and degrade rapidly to molecular oxygen in atmospheric conditions.  In this research, susceptibility of various life stages of L. serricorne, S. paniceum and O. mercator to ozone was evaluated in order to establish baseline information.  The objective of the work is to identify minimal exposure time needed to attain 100% mortality at higher ozone concentration.  Insect life stages were treated at four ozone concentrations between 1500-2400 ppm, with an increment of 300 ppm concentrations at various exposure times.  Of the three species treated, O. mercator adults were least susceptible to ozone treatment, S. paniceum adults were moderately susceptible and L. serricorne were most susceptible in all selected doses of ozone.  Mortality of treated adults increased over period of 48 h incubation.  This paper further discusses susceptibility of other life stages to ozone within a concentration of 1500-2400 ppm at various exposure times.