81 



A linear correlation coefficient was used to determine that there was 

 a 99% correlation between the alcohol emersion method and the hand 

 lens data. A X test for expected values failed to demonstrate any 

 statistical difference between the average citrus rust mite populations 

 on the ten fruit. 



This test, though lacking in replicates and large populations of 

 citrus rust mites, was carried out early in 1975 as a first indication 

 of the usefulness of the hand lens monitoring method for determining 

 citrus rust mite populations on fruit. This test did indicate a high 

 degree of correlation, but is inconclusive and needs additional repli- 

 cation. It is presented here only as on indication of the relationship 

 between the population of P^. oleivora on the equatorial belt and the 

 entire citrus rust mite population which is believed to exist on the 

 fruit. Other factors such as seasonal variation would need to be con- 

 sidered as would greater mite populations. Citrus rust mite orienta- 

 tion on the equatorial belt of the fruit is examined in the next sec- 

 tion. 



Section 2. Extrinsic and Intrinsic Orientation of 

 Citrus Rust Mite on Valencia Orange 



Introduction 



Watson and Berger (1937) described rings of russet damage corre- 

 sponding to semi-shaded areas around the fruit. They speculated that 

 this was due to an aggregative effect of the citrus rust mite and its 

 preference for these areas. Yothers and Mason (1930) demonstrated a 

 positive phototaxis but made mention of the mites avoidance of direct 

 sunlight. It was noted previously (Chapter II, Section 1) that the 

 sample about the citrus fruit equatorial belt was believed to be a 



