Table 1. Depletion t1/2 and LogD values of selected pesticides in honey and beeswax.
| Pesticide* | Honey | Beeswax | LogDa | Unpaired two tailed T-Test | ||
|---|---|---|---|---|---|---|
| kb (day-1) ± SD** |
t1/2 (day) | k (day-1) ± SD |
t1/2 (day) | p-value (t value) |
||
| Acetamiprid | 0.50 ± 0.04 | 1.4 | 0.19 ± 0.03 | 3.6 | -0.75 | 0.0004 (10.74) |
| Alachlor | 1.16 ± 0.17 | 0.6 | 0.12 ± 0.01 | 6 | 2.36 | 0.0005 (10.57) |
| DMF*** | 0.41 ± 0.05 | 1.7 | 0.12 ± 0.03 | 5.9 | -0.67 | 0.001 (8.61) |
| DMPF*** | 1.39 ± 0.4 | 0.5 | 3.47 ± 0.5 | 0.2 | 0.54 | 0.0049 (5.62) |
| Atrazine | 1.73 ± 0.6 | 0.4 | 0.58 ± 0.04 | 1.2 | 2.08 | 0.029 (3.31) |
| Bifenthrin | 0.15 ± 0.04 | 4.7 | 0.05 ± 0.007 | 15.2 | NDc | 0.013 (4.26) |
| Boscalid | 0.41 ± 0.05 | 1.7 | 0.04 ± 0.006 | 16 | 1.89 | 0.0002 (12.72) |
| Bromopropylate | 0.46 ± 0.07 | 1.5 | 0.27 ± 0.03 | 2.6 | ND | 0.012 (4.32) |
| Carbendazim | 0.99 ± 0.2 | 0.7 | 0.53 ± 0.08 | 1.3 | 0.78 | 0.021 (3.69) |
| Chlorantraniliprole | 0.87 ± 0.1 | 0.8 | 0.12 ± 0.05 | 5.9 | 1.32 | 0.0003 (11.62) |
| Chlorpyrifos | 0.36 ± 0.07 | 1.9 | 0.08 ± 0.01 | 8.8 | 2.75 | 0.0024 (6.85) |
| Clothianidin | 0.20 ± 0.03 | 3.6 | 0.10 ± 0.02 | 6.9 | -1.15 | 0.0086 (4.80) |
| Coumaphos | 0.46 ± 0.05 | 1.5 | 0.08 ± 0.009 | 8.3 | 2.34 | 0.0002 (12.95) |
| Cypermethrin | 0.14 ± 0.02 | 4.9 | 0.01 ± 0.003 | 96.3 | ND | 0.004 (11.13) |
| Diuron | 1.16 ± 0.40 | 0.6 | 104 ± 598d | 0.025 | ND | <0.0001 (> 28.96) |
| Fenbutatin oxide | 0.13 ± 0.03 | 5.4 | 0.02 ± 0.005 | 32.1 | 1.21 | 0.0033 (6.26) |
| Imidacloprid | 0.24 ± 0.03 | 2.9 | 0.17 ± 0.01 | 4.1 | -1.04 | 0.018 (3.83) |
| Iprodione | 0.77 ± 0.09 | 0.9 | 0.14 ± 0.04 | 5.0 | ND | 0.0004 (11.07) |
| Metolachlor | 1.16 ± 0.30 | 0.6 | 0.14 ± 0.04 | 5.0 | 2.28 | 0.0043 (5.83) |
| Metconazole | 0.41 ± 0.07 | 1.7 | 0.11 ± 0.03 | 6.4 | 2.11 | 0.0024 (6.83) |
| Oxadiazon | 0.22 ± 0.01 | 3.2 | 0.12 ± 0.02 | 5.9 | ND | 0.0015 (7.74) |
| Oxyfluorfen | 0.50 ± 0.06 | 1.4 | 0.28 ± 0.04 | 2.5 | ND | 0.0062 (5.28) |
| tau-Fluvalinate | 0.27 ± 0.04 | 2.6 | 0.01 ± 0.002 | 48.1 | ND | 0.0004 (11.2) |
| Tebuconazole | 0.26 ± 0.05 | 2.7 | 0.08 ± 0.01 | 9 | ND | 0.0036 (6.11) |
| Thiacloprid | 0.53 ± 0.06 | 1.3 | 0.30 ± 0.02 | 2.3 | -0.64 | 0.0032 (6.29) |
| Thiamethoxam | 0.15 ± 0.02 | 4.6 | 0.12 ± 0.03 | 5.8 | -2.06 | 0.223 (1.44) |
aLogD, Log distribution ratio, calculated as the logarithmic ratio of pesticide concentration in beeswax to honey at equilibrium.
bk, depletion rate constant obtained from the terminal slope of the pesticide concentration vs. time semi logarithmic plot. Mean k values were determined from three independent repeats.
cND, not detectable. LogD could not be determined, due to undetectable concentrations in honey.
dDepletion kinetics of diuron in beeswax is of zero order, hence the half-life depends on the initial concentration (C0) and on the linear slope (t1/2 = C0/2*k). The k unit of diuron is μg/kg/day.
*The pesticides amitraz, malathion and pyraclostrobin were not included in Table 1, since no residual concentration in honey and beeswax were found after 5 min incubation time.
**SD, standard deviation.
***DMF and DMPF, N-(2,4-Dimethylphenyl)-formamide and N'-(2,4-Dimethylphenyl)-N-methylformamidine, respectively.