Susceptibility of different life stages of saw-toothed grain beetle Oryzaephilus surinamensis (L.) (Coleoptera: Silvanidae) to modified atmospheres enriched with carbon dioxide

The susceptibility of the different life stages of the saw-toothed grain beetle Oryzaephilus surinamensis to different modified atmospheres (MAs) containing various concentrations of carbon dioxide (CO₂) was studied as an alternative to methyl bromide fumigation at 30 °C and 65 ± 5% relative humidity (r.h.). The tested MAs were 55%, 65%, 75% and 85% CO₂ gas in the air. Mortality (%) was recorded after exposure periods of 3, 6, 12, 24, 48, 72 and 96 h. Larvae and adults were more susceptible while eggs and pupae were more tolerant to CO₂. A two-day exposure period was adequate to completely kill larvae and adults under all tested MAs. All eggs and pupae were killed after four days of exposure to the high-CO₂ atmospheres (75% and 85%).     

Comparison of efficacy of nitric oxide fumigation under nitrogen and carbon dioxide atmospheres in controlling granary weevil (Sitophilus granaries) and confused flour beetle (Tribolium confusum)

Nitric oxide (NO) was a recently discovered fumigant for postharvest pest control. Because NO reacts with oxygen (O₂) spontaneously to form nitrogen dioxide (NO₂), NO fumigation must be conducted under ultralow oxygen (ULO) atmospheres to preserve NO and nitrogen (N₂) has been used to establish ULO atmospheres in NO fumigation studies in the past. However, carbon dioxide (CO₂) can also be used to ULO atmospheres and CO₂ fumigation was also reported to be effective in controlling certain insect pests and enhancing toxicity of some fumigants. In the present study, NO fumigations under ULO conditions established with N₂ and CO₂ were compared for effects against granary weevil, Sitophilus granaries, and confused flour beetle, Tribolium confusum. All life stages of the two insects were subjected to 12 h fumigation treatments with 0.5–1.0% NO at 25 °C under ULO established with CO₂ (NO–CO₂ treatments) and N₂ (NO–N₂ treatments). The most tolerant life stage for each species in each fumigation treatment was then fumigated with NO for 24 h fumigation at 25 °C to determine an effective treatment. There were no significant differences in mortalities of adults, larvae, and pupae at all NO concentrations between ULO conditions established with CO₂ and N₂ for either insect. NO–CO₂ was, however, significantly less effective than NO–N₂ against eggs of both species. Granary weevil pupae and confused flour beetle eggs were the most tolerant stages for each respective species to NO fumigation: >99% mortality of granary weevil pupae and confused flour beetle eggs were, however, achieved in the 24 h fumigation with 2% and 1% NO, respectively. This study showed that CO₂ can be used to establish ULO atmospheres for NO fumigation, but did not significantly contribute to insect mortality.     

Carbon dioxide improves ethanedinitrile efficacy for fumigating the stored product pests Rhyzopertha dominica and Lasioderma serricorne

The toxicity of ethanedinitrile (EDN), an alternative fumigant for stored products, is decreased due to the high sorption of the gas in treated commodities. This laboratory study examined adding carbon dioxide to EDN to increase activity against Rhyzopertha dominica and Lasioderma serricorne at 25 °C, 50–70% R.H and a photoperiod of 16 L:8D h for 24 h. CO₂ at 30% with the estimated LC₂₅ dose of EDN exhibited a significant effect on the mortality of adults of R. dominica and the larvae, pupae, and adults of L. serricorne. Adults emerged from the mixed life stage cultures of R. dominica exposed to a mixture of 75 ppm or 150 ppm of EDN and CO₂ at 10, 20 and 30% averaged 26.8, 11.5 and 4.9, and 1.5, 0.6 and 0.9, respectively. Averages of 188.6 and 56.6 adults resulted from cultures of R. dominica fumigated with EDN at 75 and 150 ppm alone, respectively. The L. serricorne cultures exposed to EDN at 500 or 1000 ppm plus 10, 20, and 30% of CO₂ yielded average numbers of emerged adults of 170.5, 110.9 and 114.6, and 68.3, 30.2 and 31.9, respectively, compared to 358.3 and 173.6 in cultures treated with 500 and 1000 ppm of EDN alone, respectively. Numbers of adults of both species emerged from cultures exposed to either EDN or CO₂ alone in the presence of commodities were significantly higher than those exposed to the EDN + CO₂ (30%) mixture. These results clearly indicated the positive effect of CO₂ on toxicity of EDN that can overcome the decrease of EDN toxicity against the treated insects due to its sorption in commodities.     

Effect of relative humidity on the susceptibility of Callosobruchus maculatus (Fabricius) (Coleoptera: Bruchidae) to two modified atmospheres

It is known that modified atmospheres (MA) created in a storage environment, involving high carbon dioxide (CO₂) levels (hypercarbia) or low oxygen (O₂) levels (anoxia) are detrimental to bruchid pests of grain legumes. The possibility of enhancing MA action by increasing or decreasing the relative humidity (r.h.) conditions in storage at 25±2°C was investigated against Callosobruchus maculatus (F.), a major bruchid pest of stored cowpea seeds. Mortality of eggs and adults of the bruchid in 70% CO₂ in air and 1.0% O₂ in nitrogen (N₂) was higher at 10±3% and 34±2% than at 70±2% and 90±3% r.h. Mortality of larvae and pupae of the bruchid in the atmospheres was not affected by the r.h. in storage. Development period was longer for adults emerging from bruchid eggs exposed for 12 h to these atmospheres at the lower r.h. Freshly emerged adult bruchids from treated eggs also laid fewer eggs after 12 h of exposure to these atmospheres at the lower r.h.     

Modified atmosphere packaging (MAP) as an alternative measure for controlling ten pests that attack processed food products

Modified atmospheres based on high carbon dioxide (CO₂) content offer an alternative to fumigation for arthropod pest control in durable commodities. The present study aimed to establish the efficacy of using modified atmospheres during packaging (MAP) to control a wide spectrum of pests and their respective developmental stages that affect final food products during storage and commercialization. Two high (50% and 90%) CO₂ MAPs were applied to identify the pest species and developmental stages that were most tolerant to treatments. Standard food diets containing eggs, larvae, pupae and adults of Lasioderma serricorne, Cryptolestes ferrugineus, Oryzaephilus surinamensis, Tribolium confusum, Rhyzopertha dominica, Sitophilus oryzae, Ephestia kuehniella, Plodia interpunctella, Liposcelis bostrychophila and Tyrophagus putrescentiae were confined in sealed plastic bags filled with the two MAPs. The pest species and developmental stages showed different sensitivity to the two MAP treatments. The beetles S. oryzae, R. dominica, C. ferrugineus and L. serricorne were among the most tolerant species as pupae or eggs. The mite T. putrescentiae was also highly tolerant. Moths were easier to kill than the other species tested. Our results confirmed that MAP could be applied to final food products during packaging to control the residual occurrence of pests after the manufacturing process and to prevent further infestation in the final packages reaching consumers.     

Synergistic effect of carbon dioxide atmospheres and high hydrostatic pressure to reduce spoilage bacteria on poultry sausages

Synergistic effect of combining high hydrostatic pressure (HHP) and CO₂ atmospheres has been studied against Leuconostoc carnosum, Brochothrix thermosphacta, Salmonella enteritidis, Campylobacter jejuni and Listeria innocua separately inoculated in poultry sausages. The microbial counts of the HHP treated samples (350 MPa 10 min at room temperature) and CO₂ atmosphere packaged were compared with non pressure treated and air packaged ones, analyzed at 20 h and 7 days after the treatment. The results showed a synergistic effect of the combination of these two preserving technologies against all the microorganisms studied, except in S. enteritidis which showed a greater resistance under CO₂ atmospheres, and C. jejuni, that is especially sensitive at high pressures. It seems that cell damage produced by high pressure facilitates the penetration of carbon dioxide into the microorganisms' cells, affecting their metabolism and consequently their growth. Using CO₂ atmospheres in combination with HHP treatments, pressure could be lowered without compromising the reduction of microbial counts.     

Sensitivity of different life stages of Indian meal moth Plodia interpunctella to gaseous chlorine dioxide

Gaseous chlorine dioxide (ClO₂), a possible alternative to the fumigant methyl bromide, is a strong disinfecting agent that has strong oxidizing properties and penetration ability. The Indian meal moth, Plodia interpunctella, is one of the most important insect pests of stored food, but its sensitivity to gaseous ClO₂ at different life stages has not yet been studied. We exposed all the life stages of P. interpunctella (i.e., eggs, larvae, pupae, and adults) to ClO₂ at different concentrations for different time periods. The results showed that 100 ppm and 200 ppm ClO₂ for 48 h and 24 h, respectively, resulted in 100% mortality of all P. interpunctella life stages. The order of sensitivity of P. interpunctella to gaseous ClO₂ was: egg > larva > pupa at 50 ppm and 100 ppm, and egg > pupa > larva at 200 ppm. The gas treatment affects the subsequent life stage of P. interpunctella: the gas-treated larvae fail to pupate or emerge as adults. These results suggest that gaseous ClO₂ is a possible alternative to methyl bromide, and it can effectively control all stages of P. interpunctella.     

Comparative susceptibility of Corcyra cephalonica (Lepidoptera: Pyralidae) eggs to carbon dioxide and nitrogen at different temperatures

The aim of this study was to evaluate the susceptibility of the egg stage of the rice moth Corcyra cephalonica to modified atmospheres (MAs) enriched with CO₂ or N₂ at 25, 30 and 35 °C combined with various exposure times. The tested modified atmospheres containing CO₂ were 20% CO₂, 16% O₂ and 64% N₂; 40% CO₂, 12% O₂ and 48% N_2; 60% CO₂, 8% O₂ and 32% N₂ and 80% CO₂, 4% O₂ and 16% N₂. The tested modified atmospheres containing N₂ were 97% N₂ and 3% O₂ and 98% N₂ and 2% O₂. The results showed that the hatchability responding to modified atmospheres enriched with either CO₂ or N₂ decreased significantly with an increase in exposure time, gas content (%) and temperature. All tested combinations provided complete (100%) egg control in less than 4 days. Based on 100% mortality, shorter exposures were obtained with 80% CO₂ than with N₂ at most tested temperatures. The modified atmospheres enriched with 98% N₂ were more effective than 97% N₂ against C. cephalonica eggs, especially at 35 °C. It is recommended to use high levels of CO₂ in air (80%) and N₂ (98%) in controlling 0–24-h-eggs of C. cephalonica within 24–36 h for CO₂ and 18–72 h for N₂.     

Responses of phosphine susceptible and resistant strains of five stored-product insect species to chlorine dioxide

Adults of phosphine susceptible laboratory strains and phosphine resistant field strains of five stored-product insect species were exposed in vials with 0 or 10 g of wheat for different time periods to 0.54 g/m³ (200 ppm) of chlorine dioxide gas. After exposure, adult mortality was determined 5 d later at 28 °C and 65% r.h. The 5-d mortality was 100% in laboratory and field strains of the red flour beetle, Tribolium castaneum (Herbst); sawtoothed grain beetle, Oryzaephilus surinamensis (L.); lesser grain borer, Rhyzopertha dominica (F.); maize weevil, Sitophilus zeamais Motschulsky; and rice weevil, Sitophilus oryzae (L.) that were exposed in vials with 10 g of wheat to chlorine dioxide for 26, 16, 24–34, 18–24, and 15–18 h, respectively. Corresponding exposure durations for these species and strains in vials without wheat were 15, 3, 18–20, 7–15, and 5–7 h, respectively. Dosages of chlorine dioxide producing 99% mortality (LD₉₉) of T. castaneum, O. surinamensis, R. dominica, S. zeamais, and S. oryzae strains in vials with wheat ranged from 14.79−22.57, 8.20–8.41, 15.79–21.60, 10.66–14.53, and 7.67–12.20 g-h/m³, respectively. In vials without wheat, corresponding LD₉₉ values for T. castaneum, R. dominica, and S. zeamais strains were 6.51–8.66, 11.46–23.17, and 5.79–10.26 g-h/m³, respectively. LD₉₉ values for O. surinamensis and S. oryzae could not be computed, because of 100% mortality after a 3–5 h exposure to chlorine dioxide. No adult progeny production of T. castaneum and O. surinamensis was observed after 8 weeks in control and chlorine dioxide-exposed samples. Adult progeny production of Sitophilus spp. was found only in the control samples. The dosage for 99% adult progeny reduction relative to control for R. dominica strains ranged from 10.07 to 18.11 g-h/m³. Chlorine dioxide gas is effective in killing phosphine susceptible and resistant strains of five stored-product insect species and suppressing adult progeny production of three out of the five species.     

Solubility, absorption and desorption of carbon dioxide in chicken breast fillets

The solubility for carbon dioxide (CO₂) in skinless chicken breast fillets was investigated. Henry's constant for chicken breast fillets was calculated to be 42.8 ± 3.7 Pa (mg kg^-1)^-1 at 275 K.In addition, the effects of soluble gas stabilization (SGS) time and waiting time before MA packaging on amount of solubilized CO₂ were investigated. Increasing SGS treatment time, significantly (P < 0.001) increased the amount of dissolved CO₂, while increasing waiting time significantly (P < 0.001) reduced the dissolved CO₂. Desorption of CO₂ showed to be a time consuming process, giving the industry enough time to repackage SGS treated products without loosing vast amounts of dissolved CO₂.     

Effect of sulphur dioxide concentration added at different processing stages on volatile composition of ciders

This study evaluated the effect of sulphur dioxide (SO₂) added at different steps in the process on the volatile composition contributing to the fruity aroma of cider. Potassium metabisulphite was added (150 and 300 mg/L) at three processing steps (a) crushed apple, (b) apple must and (c) final product. The SO₂ added to the crushed apple either maintained or increased the fermentation rate, whereas the addition to the apple must slowed the fermentation rate. The addition of 300 mg/L of potassium metabisulphite to Golden Delicious apple must inhibited fermentation. The losses of volatile compounds varied from 23 to 46% and from 33 to 97% in all of the treatments with 150 and 300 mg/L of potassium metabisulphite, respectively. 3‐Methyl‐1‐butanol, acetaldehyde and ethyl ethanoate corresponded to >85% of the volatile compounds in the cider; 3‐methyl‐1‐butanol was not affected by the sulphur dioxide. Acetaldehyde showed the greatest reduction (>80%) with the addition of sulphur dioxide and ethyl ethanoate was reduced when the compound was added to the crushed apple and apple must. All of the interactions between the apple variety, the stage of SO₂ addition and the concentration of SO₂ showed significant negative impact on volatile compounds. © 2018 The Institute of Brewing & Distilling     

Response of phosphine-resistant mixed-age cultures of lesser grain borer,Rhyzopertha dominica (F.) to different phosphine-carbon dioxide mixtures

Mixed-age cultures of a phosphine-resistant strain of lesser grain borer, Rhyzopertha dominica (F.) were exposed to various concentrations of phosphine and phosphine plus 10, 20 and 30% carbon dioxide combinations (CO₂) for different time intervals at 25 °C to evaluate the comparative efficacy of admixtures of phosphine-CO₂. The mortality data of the mixed age cultures were recorded taking the adult count at weekly intervals for 8 weeks. Lethal concentrations were determined by probit analysis. Phosphine with carbon dioxide exerted significant synergistic effect on the mortality of mixed-age cultures at 4, 6 and 7 days of exposure, while individually phosphine or carbon dioxide did not show a raised increase in their response. The addition of 30% carbon dioxide to lower concentrations of phosphine over shorter exposures of 4 days showed better synergistic effect among the treatments. The present study revealed that CO₂ augmented the effect of phosphine thereby reducing the concentration and exposure time required to bring about significant mortality in the mixed-age cultures of R. dominica.     

Pretreating Callosobruchus maculatus (F.) eggs in mung bean with modified atmosphere conditions influence its adult emergence and survival

Cowpea bruchid (Callosobruchus maculatus Fab.) is a cosmopolitan pest that causes economic losses to legumes during storage. The present study determined the post-effects of exposing the C. maculatus eggs in mung bean to modified atmosphere (MA) conditions on the emergence and development of adults at ambient conditions (28 ± 3 °C and 65 ± 5% RH). The 24 h old C. maculatus eggs on mung bean kernel were packed with 500 g of mung bean in nylon/linear low-density polyethylene (nylon/LLDPE) bags (12.5 × 30 cm; 80 μm thick) and sealed with air (control), 100% CO₂, 100% N₂, and vacuum for 48 h. The very low O₂ conditions in the MA package had significantly caused longer onset and developmental duration of egg to adult emergence and significantly reduced the adult emergence percentage of C. maculatus, especially those in the vacuum treatment. This was due to low pressure that disrupted the structure of the eggs as indicated by the scanning electron microscopy (SEM). In addition, the MA conditions shortened the adult emergence duration, longevity, and mortality duration. The number of females was also reduced by the low O₂ conditions, particularly in those treated with vacuum. Eggs pretreated with the MA conditions probably affected the biomolecules of the eggs that in turn have affected the growth and development of the insect, with the order of effectivity highest in vacuum followed by 100% N₂ then 100% CO₂.     

Extraction of soybean isoflavones from soybean meal with aqueous methanol modified supercritical carbon dioxide

The effects of modifier composition in terms of methanol content in water, modifier concentration, meal particle size and extraction conditions (temperature, pressure and CO₂ flow rate) on isoflavones recovery from soybean meal by supercritical carbon dioxide (SC–CO₂) extraction were investigated. The highest isoflavones recovery attained was 87.3%, at 40 °C and 50 MPa, using CO₂ flow rate of 9.80 kg/h containing a modifier 7.8 mass% of 80% (v/v) aqueous methanol. Using different modifier concentrations (60–100% methanol) at 50 MPa and 40 °C, it was shown that 80% methanol was optimum for isoflavones extraction. In addition, isoflavones recovery increased with the modifier content in SC–CO₂ up to 10.2%. The optimal particle size was 20–30 mesh with bigger and smaller particles resulting in lower isoflavones recovery. The results showed that increasing the temperature from 40 to 70 °C drastically reduced isoflavones recovery at 50 MPa. The higher the extraction pressure, the higher was the isoflavones recovery. The extraction rate increased with CO₂ flow rate but the percentage recovery was more or less the same.     

Effect of different gas stunning methods on Manchega suckling lamb meat packed under different modified atmospheres

Forty-nine Manchega breed male suckling lambs were used in this experiment. The effect of CO₂ concentration and exposure time at stunning [80% CO₂ for 90 s (G1); 90% CO₂ for 90 s (G2); 90% CO₂ for 60 s (G3); 80% CO₂ for 60 s (G4)] plus an electrically stunned control group (G5) was assessed for pH, colour (L^∗, a^∗, b^∗, C^∗ and h^∗), water holding capacity (WHC), drip loss (DL), cooking loss (CL) and shear force (SF) in samples packed under two different types of modified atmospheres (MA: MA A: 70%O₂ + 30%CO₂; MA B: 69.3%N₂ + 30%CO₂ + 0.7%CO) at 7, 14 and 21 d post-packaging. The lowest pH was found in G4 and in G5. The highest WHC and the lowest CL were found in G2 and G3 groups (P < 0.05). Modified atmospheres did not affect on pH, WHC, CL and DL, although a significant effect (P < 0.001) on colour was found at all the analysis times. Both the type of stunning and the modified atmosphere affected SF values.     

Combined effect of carbon monoxide mixed with carbon dioxide in air on the mortality of stored-grain insects

A study to determine the effect of carbon monoxide (CO) mixed with carbon dioxide (CO₂) in air on controlling stored-grain insects was conducted in the laboratory. Within modified airtight gas exposure units containing wheat at 15% moisture content wet basis (w.b.), mixed-age adults of rusty grain beetle, Cryptolestes ferrugineus (Stephens), red flour beetle, Tribolium castaneum (Herbst), and granary weevil, Sitophilus granarius (L.) were exposed for 48, 96, 144 or 192 h to three types of gas mixtures in air, 5% CO, or 30% CO₂, or 5% CO + 30% CO₂ at 20 °C and 30 °C, the balance of the gas being air in each case.Carbon monoxide alone had no effect on the mortality of adults of the three insect species. For C. ferrugineus, there was no difference in mortality between by CO₂ alone and the CO₂ + CO mixture at either temperature for all exposures. However, both T. castaneum and S. granarius had higher mortality in the CO₂ + CO mixture than the CO₂ alone at both temperatures. Moreover, S. granarius was more susceptible to CO₂ + CO mixture than T. castaneum. These results suggest that for certain species, CO could be used to increase the efficiency of CO₂, especially at high temperatures.     

Enhanced fumigant toxicity of allyl acetate to stored-product beetles in the presence of carbon dioxide

Toxicity of allyl acetate (5-25 mg/l doses) to mixed-age cultures of stored-product beetles including Cryptolestes ferrugineus, Lasioderma serricorne, Oryzaephilus surinamensis, Rhyzopertha dominica, Sitophilus oryzae and Tribolium castaneum in the presence of carbon dioxide (CO₂) (10% and 20%) with a 48-h exposure period was studied in the laboratory at 27±2 °C. Depending on dosage and the insect species, the fumigant toxicity of allyl acetate was enhanced by CO₂. At most of the allyl acetate+CO₂ combinations, increased mortality was observed in C. ferrugineus, O. surinamensis and S. oryzae. In L. serricorne and T. castaneum, which are tolerant to allyl acetate, higher mortality due to CO₂ was achieved at selected dose combinations only (e.g. 15 mg/l allyl acetate+20% CO₂). Significant increase in mortality of R. dominica (the most susceptible species to allyl acetate) exposed to allyl acetate in the presence of CO₂ was not evident except at the lower dose of 5 mg/l allyl acetate+CO₂ that caused 31.7% mortality. The mortality data show that CO₂ could be used as an adjuvant for allyl acetate.     

Susceptibility of different life stages of Indian meal moth Plodia interpunctella (Hübner) and almond moth Ephestia cautella (Walker) (Lepidoptera: Pyralidae) to modified atmospheres enriched with carbon dioxide

The susceptibility of the different life stages of the Indian meal moth Plodia interpunctella and almond moth Ephestia (Cadra) cautella to different modified atmospheres (MAs) containing various concentrations of carbon dioxide (CO₂) was studied as an alternative to methyl bromide fumigation at 27 °C and 60 ± 5% relative humidity (r.h.). The MAs tested were 40%, 60% and 80% CO₂ in air at different exposure times. Results showed that five days were adequate to kill all eggs and pupae of the two moths under all tested MAs. Exposure time needed to be extended to 6 and 7 days at 80% CO₂ to obtain complete mortality of larva of E. cautella and P. interpunctella, respectively. The order of sensitivity of P. interpunctella to MAs was: egg = pupa > larva, while for E. cautella it was: pupa > egg > larva. Generally, eggs and pupae of P. interpunctella were more sensitive to MAs than those of E. cautella but the larvae of the latter were more sensitive.     

Enhanced inactivation of pectin methyl esterase in orange juice using modified supercritical carbon dioxide treatment

The aim of the study is to quantify the effect of ethanol addition and exposure surface on the inactivation of pectin methyl esterase (PME), a juice clarifying enzyme, in orange juice using supercritical carbon dioxide (SC‐CO₂). Addition of ethanol to the SC‐CO₂ at 2% (v/v) caused greater inactivation than SC‐CO₂ alone, with a maximum reduction of PME activity of 97% at 30 MPa and 40 °C for 60 min. As the surface area to volume ratio was increased, the rate of inactivation of PME increased. Analysis of first‐order reaction kinetic data revealed that D values were greatly influenced by ethanol addition and agitation. With the addition of 2% ethanol, the D value reduced by half, that is, 56 min from 109 min. With impeller agitation of the sample at 1100 ± 100 rpm, the D value for PME was further reduced to 43 and 30 min without and with ethanol, respectively. The activity of PME treated with SC‐CO₂ remained unchanged after 14 days of storage at 4 °C. Treatment did not significantly change pH or colour, but did significantly increase the cloud values of the juice, resulting in a cloud stabilised juice with similar qualities to fresh juice.     

The effects of high concentrations of carbon dioxide in air on Trogoderma granarium Everts (Coleoptera: Dermestidae)

Several developmental stages of a laboratory strain of Trogoderma granarium Everts were subjected to an atmosphere of 60% carbon dioxide (CO₂) in air at 20 or 30°C and 60% r.h. for varying lengths of time. The eggs, pupae and adults all died within 6 days, but some larvae survived for 16 days or more at both temperatures. Larvae were then exposed at 45, 60 and 75% r.h. to 45, 60 or 75% CO₂ in air at 20 or 30°C and additionally to 30% CO₂ in air at 30°C. Mortality increased with CO₂ concentration and temperature. However, only when a CO₂ concentration of 75% at 30°C was applied did all larvae die and, even then, a 15-day exposure was required. Some survival occurred after 18 days in all other conditions. Exposure times of 10 days or less, at temperatures of 20°C or above, have been recommended for use with high CO₂ atmospheres for the control of stored products pests but this investigation shows that these may be inadequate if T. granarium is present.