51 



Laboratory Bioassay of Acaricides 



Northern fowl mites were exposed to various dosage levels of 

 acaricides to collect data necessary for dosage-mortality curves. 

 The testing procedures were adapted from those of Hall et al. (1978). 

 Tests were standardized as suggested by Peet and Grady (1928). 



Squares of muslin cloth were secured with neoprene bands over 

 the wide ends of 23"cm disposable Pasteur pipets. Acaricides were 

 dissolved in acetone and serially diluted with acetone to the desired 

 concentrations in final volumes of 100 ml. Pipets, with cloth squares 

 in place, were immersed in the acaricide solutions for ca . 20 sec, then 

 removed and rolled on paper towelling to dry the outsides. Control 

 pipets were treated with 100 ml of acetone. Next, pipets were tapped 



on paoer towelling for 2 min, tapered ends down, to dry the ins ides. 



TM 

 More complete drying was achieved by using a Gast electric pump to 



force air through the pipets for 20 min. Pipets were removed from the 

 pump and used within 1 hr. 



After pipets were ready for use, mites were collected from caged 

 chickens at the University of Florida Poultry Science Farm and trans- 

 ported to the laboratory. Mites were emptied into a porcelain emesis 

 basin which was placed inside a larger pan half-filled with water to 

 prevent mites from escaping. The vacuum side of the above-mentioned 

 pump was fitted with a length of neoprene tubing and the pressure set 

 at 106 g/cm 2 . The large ends of the pipets, with cloth squares attached, 

 were slipped into the open end of the neoprene tubing. When the pump 

 was turned on, mites were pulled into the pipets. After the desired 

 number of mites were inside, the pipets were removed from the tubing. 

 The tapered ends were snipped with a hemostat to a length that would 



