Table 1. Proportion of colonies (in two wintering methods) with detectable levels of parasites or pathogens.
| Wintering method | Season | Number of colonies | Varroa (%) | Tracheal mite (%) | Nosema* (%) # | DWV (%) | BQCV (%) | SBV* (%) # | IAPV* (%) | KBV* (%) | CBPV (%) | ABPV (%) |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Indoor | Fall | 45 | 69 | 4 | 53a | 100 | 98 | 40a | 13 | 11 | 13 | 2 |
| Mid-winter | 45 | 56 | 9 | 87b | 87 | 82 | 84b | 33 | 18 | 13 | 16 | |
| Spring | 40 | 58 | 10 | 90b | 98 | 88 | 73b | 20 | 20 | 13 | 10 | |
| Outdoor | Fall | 30 | 83 | 3 | 47 | 100 | 100 | 50 | 13 | 13 | 10 | 3 |
| Spring | 26 | 73 | 8 | 96 | 96 | 92 | 85 | 50 | 46 | 35 | 8 | |
| Pooled | Fall | 75 | 76 | 3.5 | 50 | 100 | 99 | 45 | 13 | 12 | 11.5 | 2.5 |
| Pooled | Spring | 66 | 65.5 | 9 | 93 | 97 | 90 | 79 | 35 | 33 | 24 | 9 |
The levels of parasites or pathogens as measured by the alcohol wash method for Varroa on adult bees collected in the brood area (250 bees) and from colony entrances (200 bees approximately), spore count for Nosema spp (from 100 bees), thoracic slice method for tracheal mite (100 bees), and RT-PCR for viruses using 50 bees for brood area and 10 bees for entrance samples.
* = Overall seasonal change in prevalence (see results for statistics) from fall to spring averaged over both wintering methods.
# = Comparisons within indoor-wintered colonies for changes in seasonal prevalence (see results for statistics) proportions followed by the same letter within indoor-wintering hives are not significantly different (P > 0.05).
DWV = deformed wing virus; BQCV = black queen cell virus; SBV = sacbrood virus; IAPV = Israeli acute paralysis virus; KBV = Kashmir bee virus; CBPV = Chronic bee paralysis virus; ABPV = acute bee paralysis virus.