FUMIGATION AGAINST GRAIN WEEVILS 



19 



quiiioline, quinaldine, and, piperazine. The minimum toxic concen- 

 tration of pyridine was 25 grams per 100 cubic centimeters of solu- 

 tion. None of these compounds was more than one-hundredth as 

 effective as nicotine. 



McClintock, Hamilton, and Lowe (IS) found little difference in 

 the toxicity of pyridine, pyridine bases, and quinoline for bedbugs, 

 cockroaches, house flies, clothes moths, and mosquitoes. 



Jewson and Tattersfield (10) found pyridine effective against mites. 



Lefroy (11) found that quinoline and pyridine killed some of the 

 mealworms dipped in the liquids, but that a 1 per cent aqueous 

 solution of nicotine -killed none. 



Tattersfield and Roberts (2If) found that pyridine was moderately 

 toxic against wire worms. 



Moore (15) found pyridine somewhat more toxic than its position 

 in the table of organic compounds arranged according to volatility 

 would indicate. Its toxicity was about the same as that of furfural. 



INORGANIC COMPOUNDS 



None of the inorganic compounds tested proved suitable as a 

 fumigant. Thionyl chloride killed all weevils at a concentration of 

 4.5 per cent; concentrations of carbon dioxide ranging from 50 to 100' 

 per cent were required to effect a complete kill. 



RELATION BETWEEN VOLATILITY AND TOXICITY OF FUMIGANTS 



The compounds causing 100 per cent mortality to S. oryza (selected 

 on account of its high resistance to fumigants) exposed to them for 

 24 hours, together with their boiling points, are listed in Table 3. 



Table 3. — Toxicity of fumigants to Sitophilus oryza (arranged in order of decreasing 



effect) 



Fumigant 



E pichlorohy drin 



Pheny lacetonitrile 



Cbloroaeetophenone 



Methyl thiocyanate 



Acetophenone 



Chloroacetone 



Benzaldehyde 



Ally] isothiocyanate 



Crotonaldehyde 



Ethylene bromide 



Isopropy 1 formate 



Mesity 1 oxide. 



Isoamyl nitrite 



Ethyl formate 



n-Buty 1 nitrite 



n-Butylamine 



Methyl cyano formate. 

 Propylene dichloride . 



Furfural 



Trichloroethane 



Isoamyl alcohol 



n-Butyl Iodide 



Ethyl thiocyanate 



Pyridine 



Minimum 

 concentra- 

 tion caus- 

 ing 100 per 

 cent mor- 

 tality in 24 

 hours 



Per cent 



3 0.09 



.10 



.10 



.10 



3 .16 



.26 



3 , 27 



a! 34 



3.50 



.50 



3 .50 



.55 



».60 



.00 



.60 



.60 



.68 



3.70 



8.80 



.80 



.80 



.80 



.80 



.83 



Boiling 

 point i 



'C. 

 116.6 

 231.7 

 247.0 

 133.0 

 202.0 

 119.0 

 178.3 

 150.7 

 104.0 

 129.0 

 70.0 

 130.0 

 99.0 

 54.4 

 75.0 

 76.0 

 100.0 

 96.8 

 161.0 

 74.1 

 131.0 

 129.9 

 140.0 

 116.0 



Minimum 

 quantity 



causing 100 

 per cent 



mortality 



in 24 hours 



Lbs. per 



1,000 cu. ft. 



0.23 



.33 



.43 



.20 



.54 



.67 



.80 



.94 



.98 



2.62 



1.23 



1.50 



1.96 



1.24 



1.72 



1.22 



1.61 



2.20 



2.14 



2.97 



1.96 



4.10 



1.94 



1.83 



Cost per 

 pound 2 



Dollars 

 27.22 

 18.14 



9.07 

 27.22 



5.90 

 27.22 



1.13 



4.08 



.91 

 2.27 

 13.61 

 9.07 

 .40 

 3.63 

 36.29 



1.27 



.25 



2.27 



1.81 



9.07 



22.68 



.36 



Cost per 



1,000 cubic 



feet 



Dollars 

 6.26 

 5.99 

 3.90 

 5.44 

 3.18 

 18.24 

 .90 

 3.84 



2.38 



2.79 



20.42 



17.78 



.50 



6.24 



44.27 



2.79 

 .54 

 6.74 

 3.55 

 37.19 

 44.00 

 .66 



! Boiling points taken from Beilstein. 



i Most of the prices are taken from List No. 10 of the Eastman Kodak Co., Rochester, N. Y., issued 

 September, 1023; some are from Wholesale quotations by the Oil, Paint, and Drug Reporter, March 3, 1924; 

 me are quotations from the Miner Laboratories, i hicago, 111. 

 fiimum concentrations tested; 



