Evaluation of carbon dioxide treatments at high pressure and at differenttemperatures against Plodia interpunctella (Hübner) (Lepidoptera: Pyralidae)and Sitophilus oryzae (L.) (Coleoptera: Curculionidae)

Abstract: The application of CO2 at high pressure has been used as an alternative treatment tomethyl bromide for the control of insect pests on high value stored products. However, theapplication of high pressure treatments represents an important capital investment. On the otherhand, heat treatments are also alternative treatments that are commercially available, althoughhave high energy consumption and can affect the quality of the treated food product. In order toimprove the efficacy of both treatments and achieve a reduction in the exposure time, weevaluated the possibility of the combined use of pressure and temperature treatment. We testedthe effect of two pressures (20 and 10 bar) in combination with four different temperatures (50,45, 40 and 25°C) on the mortality of Plodia interpunctella eggs and Sitophilus oryzae eggs andlarvae. When CO2 was applied at 20 bar and 25°C, total mortality was achieved after 10 minutesfor P. interpunctella eggs and after 60 and 40 minutes for S. oryzae eggs and larvae, respectively.The reduction of pressure to 10 bar, that needs half the amount of CO2 and implies a reduction ofcost, increased the treatment time to 60 minutes for P. interpunctella and 240 minutes forS. oryzae. However, with the combined use of pressure and temperature, efficacy was achievedwithin a shorter exposure time, and for a pressure of 10 bar and a temperature of 40°C, only 10minutes were needed for total mortality of P. interpunctella and 60 minutes for S. oryzae eggsand larvae.