- 2 - 



EAOKOaOUI-TD AMD PURPO.SE OF STUDY 



Emphasis during recent years on :;,Tain sanitation has stressed the 

 necessity for a rapid and simple method of deterriining the amo"ant of 

 larval infestation in wheat (comnonly teinad internal infestation). 

 Various methods are available to the trained technician, but they are 

 not in general s-'oitable for use by commercial c^ain handlers. Investi- 

 gations of separation of infested from noninfested wheat by flotation 

 were conducted at I-Ianhattan, Kans., 1.9$2-$hi and the results are re- 

 ported here, 



Frankenfeld (U) -^ developed the acid fuchsin stain method for de- 

 tecting hidden infestation in wheat. The fuchsin stains the gelatinous 

 plugs which cover the punctiu?es in the kernels through iviiich the eggs 

 were deposited. The degree of internal infestation can then be esti- 

 mated from the number of plugs observed. 



Apt (2_) found that v:heat kernels with holes by which weevils have 

 emerged can be segregated from so^jnd wheat by a flotation method in 

 which wheat samples are submerged in a solution of ferric nitrate. The 

 solution does not flow into the hole to fill up the void left by the 

 emerged adu2t, and the trapped air floats the kernel. Determining the 

 number of infested kernels per IX-gTaiti sample was formerly the method 

 advocated by the Food and Drug Administration (8) for establishing 

 whether wheat met the requirements for freedom from weevil infestation. 



Another relatively efficient method is the cracking-flotation tech- 

 nique (£) , Kernels of wheat are rough ground or cracked s^afficiently to 

 release the imraature forms of the weevils, which are then segregated in 

 solutions of alcohol and gasoline. This method requires use of the 

 microscope to identify the insects or their heads. 



The most efficient method of deteriiiining the degree of internal in- 

 festation in -vdieat to date is use of the X-ray {Jj 9). Radiographs are 

 made from a sample of wheat and these are scanned for infested kernels. 

 Various techniques such as the soda straw technique (3) have been used 

 to make examination of the negatives easier. 



Another method of detection is the sodium hydroxide gelatinization 

 process (1) wherein wheat kernels are boiled in a solution of sodium 

 hydroxide until the more advanced stages of internal infestation become 

 visible (6) , 



limitations common to the foregoing methods are that they are time 

 consuming, expensive, technical, or not adapted for field use. 



Earlier studies (10) had proved that there is a detectable loss in 

 weight of wheat kernels infested with the rice weevil after only 1 xijeek 

 of larval feeding. 



y I'lunbers in parentheses refer to Literature Cited, p, 5. 



