SUGGESTED CONDITIONS AND PROCEDURES 



FOR USING CARBON DIOXIDE TO 



CONTROL INSECTS IN GRAIN STORAGE FACILITIES 



By Edward G. Jay 1 



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INTRODUCTION 



The information contained in this report was 

 derived from tests conducted by entomologists and their 

 coworkers. 2 The report is not to be considered a final 

 reference work on the application of carbon dioxide 

 (C0 2 ) in grain storage facilities because more 

 economical methods may be developed; however, it 

 should serve as a guide to those who wish to use or 

 further investigate this promising residue-free method of 

 insect control. 



Each storage facility will have its own peculiarities, 

 which include areas to seal, access ports, and other 



factors pertaining to the application and distribution 

 of the C0 2 . Therefore, the information contained in 

 this report is written for a general situation and 

 does not pertain to any one type of storage 

 facility. The information was gathered from research 

 conducted in metal bins and concrete silos of 600- to 

 68,000- bushel capacities. The technique has not yet 

 been tried in flat storage. Additional information on this 

 promising control technique may be obtained from 

 companies who sell C0 2 or by contacting the author 

 directly. 



CONDITIONS AND CONCENTRATION LEVELS FOR APPLYING CO, 



Temperature 



The temperature of the grain should be above 

 70° F. during the application of the C0 2 . Insects 

 are active at higher temperatures, and thus their 

 respiration rates are increased. This increases the 

 effectiveness of the gas against the insects. 



Concentration of C0 2 



If a C0 2 concentration of 60 percent is maintained 

 for 4 days, it will kill most species and life stages of 

 stored-product insects including larvae and pupae of the 

 Sitophilus weevils and of the lesser grain borer, 

 Rhyzopertha dominica, (F.). Eggs and adults of several 

 species of moths and beetles are killed in shorter 

 exposure periods. When a storage facility is purged to 



'Research entomologist, Market Quality Research Division, 

 Agricultural Research Service, U.S. Department of Agriculture, 

 Savannah, Ga. 31403. 



2 The efforts of the following Market Quality Research 

 Division personnel who assisted in various phases of this research 

 are acknowledged: G.C. Pearman, A. Cagle, L.M. Redlinger, and 

 H. Hall. 



this C0 2 concentration, the resulting oxygen 

 concentration will be reduced from 21 percent to a 

 concentration within the range of 7 to 10 percent. 



If the C0 2 concentration of 60 percent cannot be 

 attained and maintained for 4 days, a concentration of 

 45-percent C0 2 should be maintained for 5 to 6 days, or 

 a concentration of 35-percent C0 2 should be maintained 

 for 7 days. Concentrations above 60-percent C0 2 seem 

 to have little added effect on the efficiency of the 

 control method. Therefore, any attempts to maintain a 

 concentration higher than this is a waste of C0 2 . 



Bioassay 



A method of determining if the C0 2 is effective is 

 to observe the mortality of caged live insects held in the 

 headspace or probed down into the grain mass during 

 the treatment. Observed mortality of caged adult insects 

 cannot be interpreted as evidence that all the insects in 

 the grain were killed because the larvae and pupae of 

 most insects, especially those living within the kernels, 

 are harder to kill than the adults. However, this 

 technique can be used as an indicator of the efficiency 

 of the treatment. 



