I certify that I have read this study and that in my opinion it 

 conforms to acceptable standards of scholarly presentation and is 

 fully adequate, in scope and quality, as a dissertation for the degree 

 of Doctor of Philosophy. 



Dr ./Jerry F. Butler, Cha i r m a n 

 Professor of Entomology and 

 Nematology 



I certify that I have read this study and that in my opinion it 

 conforms to acceptable standards of scholarly presentation and is 

 fully adequate, in scope and quality, as a dissertation for the degree 

 of Doctor of Philosophy. 



\w\ G SN* 



Dr. David G. Ye»tfng, Co^hairman 

 Associate Professor of Entomology 

 and Nematology 



I certify that I have read this study and that in my opinion it 

 conforms to acceptable standards of scholarly presentation and is 

 fully adequate, in scope and quality, as a dissertation for the degree 

 of Doctor of Philosophy. 



Dr* - . Stephen GT'Zam 



Associate Professo 



and Cell Science 



of Microbiology 



