Table 2.
Summary of minimum adequate models selected by inference on likelihood ratio tests. Effects of treatment (factor with four levels: control, concealed-nectar mix, mixed plots, and open-nectar mix), sampling month (factor with three levels *: June, July and August), and the interaction between treatment (T) and month (M) on natural enemy richness, abundance of aphidophagous taxa, non-aphidophaous natural enemy taxa, aphid colony densities, and egg card predation within adjacent apple trees in each year. Arthropods sampled on ten trees (five branches per tree) per plot on five separate occasions each year in four orchards. Degrees of freedom (d.f.), test statistics (LRT) and p-values from likelihood ratio tests are shown. p-values of fixed effects included in final models are presented in bold (p < 0.05).
| 2012 | 2013 | ||||||
|---|---|---|---|---|---|---|---|
| Within Crop | Within Crop | ||||||
| Response | Predictor | d.f. | LRT | p | d.f. | LRT | p |
| Natural enemies | |||||||
| Richness | Treatment | 3 | 2.40 | 0.493 | 3 | 2.65 | 0.449 |
| Month | 2 | 34.80 | <0.001 | 2 | 0.60 | 0.742 | |
| T × M | 6 | 2.32 | 0.888 | 6 | 1.09 | 0.982 | |
| Aphidophagous taxa | Treatment | 3 | 6.35 | 0.096 | 3 | 1.93 | 0.587 |
| Month | 2 | 18.29 | <0.001 | 2 | 5.61 | 0.060 | |
| T × M | 6 | 6.16 | 0.406 | 6 | 11.25 | 0.081 | |
| Other taxa | Treatment | 3 | 13.87 | 0.003 | 3 | 12.77 | 0.005 |
| Month | 2 | 83.47 | <0.001 | 2 | 3.33 | 0.189 | |
| T × M | 6 | 5.01 | 0.543 | 6 | 7.76 | 0.256 | |
| Pest control | |||||||
| Aphid colonies | Treatment | 3 | 1.54 | 0.672 | 3 | 3.88 | 0.275 |
| Month | 2 | 18.97 | <0.001 | 2 | 55.28 | <0.001 | |
| T × M | 6 | 9.37 | 0.154 | 6 | 5.39 | 0.495 | |
| Egg cards | Treatment | - | - | - | 3 | 9.54 | 0.023 |
| Month * | - | - | - | 3 | 77.71 | <0.001 | |
| T × M | - | - | - | 9 | 15.58 | 0.076 | |
* Egg card data collected over four months (June–September 2013).