Table 1. Effect of fixative protocols on detection of prey DNA, quantity of prey DNA detected (in egg equivalent) and total DNA in sample (including predator and prey). Prey is a single CPB egg, fed to C. maculata larva, fixed immediately after cessation of feeding.
| trt.no. | Treatment | n | % detect | egg equivalent se | total DNAb (pred+prey) se |
|---|---|---|---|---|---|
| 1 | Egg positive control (frozen in EtOH) | 10 | 100% | 1.0000 ± 0.1233 | 1.72 ± 0.14 |
| 2 | Freeze EtOH | 9 (11)a | 100% | 0.2284 ± 0.0571 | 21.63 ± 1.81 |
| 3 | Freeze −80°C | 11 (12) | 100% | 0.0604 ± 0.0207 | 21.03 ± 2.08 |
| 4 | Freeze −20°C | 10 | 90% | 0.0279 ± 0.0051 | 17.44 ± 1.64 |
| 5 | Room temp EtOH | 10 | 80% | 0.0078 ± 0.0015 | 16.08 ± 1.55 |
| 6 | Antifreeze | 10 | 90% | 0.0071 ± 0.0013 | 6.43 ± 3.61 |
| 7 | CO2, 4h | 9 | 22% | 0.0012 ± 0.0009 | 19.08 ± 1.41 |
| 8 | CO2, 5d | 10 | 0% | 0 ± 0 | 9.73 ± 1.60 |
| 9 | Unfed control (frozen in EtOH) | 10 | 0% | 0 ± 0 | 16.04 ± 1.58 |
| TEST (trt. no compared) | % detectc | egg equivalentd | total DNAd | ||
| Overall significance of treatment (2, 3, 4, 5, 6, 7, 8) | p<0.0001 (χ2(6)=46.80) | p<0.0001(H(6)=51.63) | p<0.0001 (H(6)=39.02) | ||
| Orthogonal contrasts: | |||||
| Contrast: frozen (2, 3, 4) vs. warm (5, 6, 7, 8) | p<0.0001 (n=70) | p<0.0001 (U’=1129.5) | p<0.0001 (U’=1024.5) | ||
| Contrast within frozen: solvent (2) vs. dry (3, 4) | ns | p=0.0058 (U’=155.5) | ns | ||
| Contrast within warm: solvent (5, 6) vs. dry (7, 8) | p<0.0001 (n=40) | p<0.0001 (U’=331) | ns | ||
| Contrast within frozen dry: −80°C (3) vs. −20°C (4) | ns | ns | ns | ||
| Contrast within warm solvent: EtOH (5) vs. Antifreeze (6) | ns | ns | p=0.0005 (U’=96) | ||
| Contrast within warm dry (CO2): 4h (7) vs. 5d (8) | ns | ns | p=0.0015 (U’=84) | ||
| Contrasts with controls: | |||||
| Contrast within frozen solvent: fed (2) vs. egg control (1) | ns | p=0.0003 (U’=89) | --- | ||
| Contrast within frozen solvent: fed (2) vs. unfed control (9) | --- | --- | p=0.0166 (U’=89) | ||
| Contrast warm dry (7, 8) vs. unfed control (9) | ns | ns | ns | ||