Ecological Archives E083-049-A1

Mark Vicari, P. E. Hatcher, and P. G. Ayres. 2002. Combined effect of foliar and mycorrhizal endophytes on an insect herbivore. Ecology 83:2452-2464.

Appendix A. Variables affecting survivorship of second-, third-, fourth-, and fifth-instar Phlogophora meticulosa larvae feeding on Lolium perenne as determined by logistic regression using the backward conditional method of model building.

Variables affecting likelihood of survivorship  B  S.E  Walddf  P  Variation
 explained by 
 model (%)
           
  Instar 2:        
84.7
   M  -0.65  0.29   4.981   0.026  
   E  -0.69  0.30   5.461   0.019  
   Constant  -1.11  0.22  26.171  <0.001  
           
  Instar 3:        
81.7
   E × Ma  -0.94  0.39   5.741   0.017  
   M × Pb   0.75  0.35   4.591   0.032  
   Trial      22.483  <0.001  
    Trial 1  -0.18  0.37   0.231   0.632  
    Trial 2  -1.10  0.47   5.541   0.019  
    Trial 3   1.19  0.40   8.811   0.003  
   Constant  -1.38  0.27  25.271  <0.001  
           
  Instar 4:        
89.4
   P   1.04  0.44   5.541   0.019  
   Trial      10.843   0.013  
    Trial 1   0.66  0.51   1.651   0.199  
    Trial 2  -1.02  0.71   2.041   0.153  
    Trial 3   1.31  0.63   4.361   0.037  
   Constant  -2.94  0.50  34.781  <0.001  
           
  Instar 5:        
84.8
   M  -1.10  0.41   7.291   0.007  
   E  -1.20  0.61   4.591   0.048  
   E × P   2.56  0.63  16.501  <0.001  
   Trial      16.703   0.001  
    Trial 1   1.43  0.50   8.121   0.005  
    Trial 2  -0.52  0.59   0.771   0.398  
    Trial 3   1.42  0.72   4.011   0.049  
   Constant  -1.87  0.47  15.711  <0.001  
           

   Note: Variables in the initial model included mycorrhizal infection (M), foliar endophyte infection (E), phosphorus fertilization rate (P), all two- and three-way interactions of the above, and trial. Variables with P > 0.10 were eliminated from the models in a stepwise manner, starting with the variable with the largest P value (Norusis 1993).
Positive B indicates survivorship was higher in the presence of infection / at high P / in trial 4.
aLarval survivorship (pooled across P treatments) in
    -M-E treatments = 87%
    -M+E treatments = 74%
    +M-E treatments = 82%
    +M+E treatments = 80%
bLarval survivorship (pooled across E treatments) in
    low P, -M treatments = 77%;
    low P, +M treatments = 81%;
    high P, -M treatments = 85%;
    high P, +M treatments = 81%

Literature cited

Norusis, M. J. 1993. SPSS for Windows advanced statistics. SPSS, Chicago, Illinois, USA.


[Back to E083-049]