Table 1.

Summary of main fixed effects treatment (factor with two levels: flower strip or wheat control strip), distance from flower or control strip (continuous variable) and their interaction on wheat plant damage (arcsine-square root-transformed), cereal leaf beetle (CLB) density and the density of different natural enemy groups in adjacent winter wheat fields and within the strips themselves (only natural enemies). Degrees of freedom (d.f.), χ2-values and p-values from likelihood-ratio tests of the model selection procedure (see Material and methods section) are shown. p-values of explanatory variables that were included in the final model are in bold lettering.

within winter wheatwithin strip
d.f.χ2pd.f.χ2p
pest density
 CLB larvae
 treatment14.930.026
 distance18.200.004
 treatment × distance10.510.474
 CLB adults
 treatment14.510.034
 distance10.060.830
 treatment × distance11.610.205
plant damage
 wheat plant damage by CLB
 treatment14.390.036
 distance11.130.288
 treatment × distance12.790.098
natural enemy abundance
 ground beetles (adults)
 treatment10.600.437110.600.001
 distance10.510.478
 treatment × distance19.480.002
 predatory bugs (adults and nymphs)
 treatment12.860.09114.420.036
 distance10.380.540
 treatment × distance10.000.989
 lacewings (adults)
 treatment10.140.714150.58<0.0001
 distance10.050.818
 treatment × distance13.260.071
 lacewings (larvae)
 treatment10.970.32410.990.319
 distance10.110.744
 Treatment × Distance10.010.909
 ladybirds (adults)
 treatment10.040.839137.53<0.0001
 distance10.440.507
 treatment × distance12.240.134
 ladybirds (larvae)
 treatment10.100.74810.250.619
 distance111.990.001
 treatment × distance10.000.964