The use of modified and controlled atmospheres for the disinfestation of stored products

Abstract

Storage insects are aerobic organisms requiring oxygen for their survival. Therefore, they respond to altered atmospheric gas compositions containing low O 2 or high CO 2 . The lower the grain moisture content (m.c.) and the corresponding intergranular humidity, the higher the mortality-due to the desiccation effect on insects caused by low O 2 or elevated CO 2 concentrations. To achieve insect control, the temperature of the grain should be above 21°C. Hermetic storage is based on the principle of generation of an oxygen-depleted, carbon dioxide-enriched interstitial atmosphere caused by the respiration of the living organisms in the ecological system of a sealed storage. A sufficiently low oxygen and elevated CO 2 atmosphere is created through a natural metabolic process based on insect respiration and, in cases where the commodity has sufficiently high moisture, the respiration of the microorganisms within a sealed storage system. An O 2 ingress rate of 0.05 %/day is sufficient to arrest the theoretical weight loss at a level of 0.018 % over 1-year storage period. At this ingress rate, the possibility of a residual surviving insect population is eliminated. This low O 2 ingress level could serve as a guideline for the sealing specifications of structures appropriate to the hermetic storage method. The applications for which hermetic technology has been most widely accepted are (a) for longterm storage of cereal grains, primarily rice, corn, barley, and wheat; (b) for long-term storage of a variety of seeds to preserve germination potential and vigor, and (c) for quality preservation of high-value commodities, such as dried fruits.

Lethal effects of CO2-modified atmospheres for the control of three Bruchidae species

“…Pupae, which are presumed to have the lowest oxygen demand, were the most tolerant to hypercarbia, while adults, with their high metabolic rates, were the least tolerant, as previously shown for Callosobruchus subinnotatus Pic (Mbata et al, 2000). Temperature, as a factor that regulates insect activity, directly affects the consumption of O 2 and therefore the efficacy of the MA, as discussed by Navarro (2012). The temperature tested in the present study is the optimum for the development of the three bruchids (Arbogast, 1991;Howe and Currie, 1964) and the control obtained with MA's was therefore when these insects were at their maximal biological potential.…”

Effects of Hermetic Storage on Adult Sitophilus oryzae L. (Coleoptera: Curculionidae) Acoustic Activity Patterns and Mortality

“…We found there was little insect activity after the O 2 depleted to 5% and activity completely ceased after a level of 2%. Previous research has shown that O 2 levels below 3% are most effective in controlling infestations (Navarro 1978, 2012; Moreno-Martinez et al 2000). At farm level with hermetic bags like Purdue Improved Crop Storage (PICS) bags, O 2 levels below 5% are achievable ((Baoua et al 2014; Tubbs et al 2016) and according to literature 5% also causes mortality but requires longer exposure time (Bailey 1955).…”

Comparative efficacy of modified atmospheres enriched with carbon dioxide against Cadra (=Ephestia) cautella

“…41 It has been shown previously that, in MAs, temperature has an important effect on efficacy, 17,20,21 and an increase in temperature generally increases the mortality rate and shortens the lethal time 49 by increasing metabolic activity. 38,50 In respect of temperature differences, in the present study the exposure periods required for complete mortality of eggs, larvae, pupae, and adults at 20 ∘ C were found to be ca. 56 h and 68 h more than those reported at 27.5 ∘ C and 32.5 ∘ C, respectively, by Tutuncu et al 20…”