Table 2.
Honey bee amitraz bioassay summary. The LD50 values are in shown in units of ng amitraz/mg bee. The LD50 values were considered significantly different if the 95% CI of the LD50 values did not overlap between colonies or test dates. Letters and numbers beside LD50 values indicate significant differences in rows and columns, respectively. The LD50 value for the IPM treatment group in October was not reported as the data were not well represented by a line.
| Month | Control | Amitraz | IPM | ||||||
|---|---|---|---|---|---|---|---|---|---|
| n | LD50 (95% CI) | Slope (SE) | n | LD50 (95% CI) | Slope (SE) | n | LD50 (95% CI) | Slope (SE) | |
| May | 373 | 20.0 (18.4–21.8) b3 | 4.9 (0.4) | 339 | 17.6 (15.8–19.6) b5 | 3.7 (0.3) | 320 | 27.1 (24.7–29.7) a4 | 4.2 (0.4) |
| June | 380 | 59.4 (51.5–72.9) a1 | 3.4 (0.4) | 416 | 33.7 (31.1–36.6) b23 | 4.1 (0.4) | 368 | 46.8 (42.0–53.5) a12 | 3.5 (0.4) |
| July | 429 | 20.1 (18.5–21.9) a3 | 4.2 (0.3) | 238 | 19.5 (17.6–21.8) a5 | 5.0 (0.5) | 218 | 18.4 (16.3–20.9) a3 | 4.4 (0.5) |
| August | 324 | 23.8 (19.9–28.5) ab3 | 2.2 (0.3) | 328 | 25.3 (22.7–28.1) a4 | 3.5 (0.3) | 568 | 18.5 (16.7–20.5) b3 | 2.6 (0.2) |
| September | 327 | 60.6 (55.7–5.8) a1 | 4.3 (0.5) | 180 | 41.0 (35.8–46.1) b123 | 4.0 (0.6) | 255 | 36.4 (31.1–41.2) b2 | 4.0 (0.5) |
| October | 321 | 30.6 (28.5–32.3) b2 | 9.1 (1.3) | 350 | 42.4 (38.9–46.3) a12 | 4.4 (0.5) | NA | NA | NA |