THE USE OF A VAPOR GENERATOR WITH DICHLORVOS 



,\3(^T0 CONTROL DROSOPHILA IN WINERIES 1/ 



Albert P. Yerington, Preston L. Hartsell, and Rodney D. Fries_2/ 



SUMMARY 



A semiautomatic vapor generator to dispense insecticidal vapor from resin 

 pellets containing 20- percent dichlorvos was tested for controlling drosophila in 

 wineries. Preliminary tests showed that the machine could be operated successfully 

 in wine cellars. 



Use of the machine for 20 or 30 minutes on each of 5 consecutive days in a 

 161,284 cu. ft. cellar gave excellent control of drosophila. Two or three treatments 

 per week for 9 weeks out of 14 considerably reduced the drosophila population in a 

 268,495 cu. ft. cellar. Mortalities for caged insects were: Drosophila, 97 percent; 

 dried- fruit beetle, 54 percent; and pineapple beetle, 82 percent. Thirty pounds of 

 pellets were used but were not enough for this cellar for an entire grape crushing 

 season. On the basis of mortalities of caged drosophila, concentrations of less than 

 6 /Ltg/cu. ft. were ineffective. One- half hour after the treatment, 9 percent of the 

 dichlorvos had been lost from the air, and after 1 hour, 50 percent. 



A taste panel found no off- flavor in wine that had been exposed uncovered to 

 the vapor for 3 hours. Dichlorvos residues were less than 0.03 p.p.m. , the 

 sensitivity of the chemical method used. Tests of wines stored in covered wooden 

 wine tanks during 15 dichlorvos treatments had similar results. 



1/ This study was made at the Dried Fruit and Tree Nut Insects Investigations, 

 Fresno, Calif., a unit of the Stored- Produdt Insects Research Branch, Market 

 Quality Research Division. 



2/ Research entomologist, physical i^cience technician, and agricultural 

 research technician, respectively, Dried Fruit and Tree Nut Insects Investigations, 

 Market Quality Research Division, Agricultural Research Service, U. S. Department 

 of Agriculture, Fresno, Calif. 93727. 



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