CHAPTER II 

 BIOLOGICAL STUDIES OF THE CITRUS RUST MITE 



Section 1. Methods for Monitoring Citrus Rust Mites 

 Introduction 



Early researchers used linen testers and 0.5 in. holes cut in 

 paper to help define the field of view sampled in citrus rust mite 

 counts (Yothers and Miller, 1934; Osburn and Mathis, 1944). Later 

 researchers used the entire field of view of a lOX hand lens (Pratt, 

 1957; Johnson, 1969; Simanton, 1960) to count mite populations. The 

 lack of uniformity of method and surface area examined by earlier re- 

 searchers dictated the need for a method of monitoring which delineates 

 the field of view. This study defines the field of view and relates 

 samples taken to the entire mite population on the fruit. 

 Materials and Methods 



Valencia orange trees located in Orange Lake, Florida, were used 

 in this study. Fruit size ranged from 3.4 to 4.2 cm, and were cho- 

 sen randomly from a five acre plot. 



Hand lens method . A 14X Bausch & Lomb'^ hand lens was used to 

 count the numbers of rust mites per cm"^ on the surface of oranges. A 

 rubber stamp was used to stamp a square 1 cm area on the fruit. Three 

 areas were randomly counted on each fruit along its equatorial belt. 

 Diameter was taken with aluminum calipers and a metric rule. Circum- 

 ference was taken later in the laboratory by placing a fresh red line 

 on the fruit vertically over its equator, then rolling it along the 



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