This investigation was undertaken to determine whether active ingredients (AIs) of currently recommended plant protection products (PPPs) could be transferred to beehives from apple and pear trees. A field trial was carried out with apple trees of Ligol and Idared variety, and pear trees of Conference variety. For pest and diseases control of fungal origin, recommended PPPs were applied. Samples of flowers from the above-mentioned varieties of fruit trees, of bees, brood and honey from beehives located in their direct neighborhood were collected regularly and analyzed for the presence of lambda-cyhalothrin (an insecticide) and cyprodinil, captan, fluopyram, kresoxim-methyl, penthiopyrad and trifloxystrobin (fungicides). In samples of flowers of Ligol variety, fluopyram residues (on average 0.621 µg single flower⁻¹) were at the highest levels, whereas in samples of pear flowers of Conference variety, and in flowers of Idared variety, captan residues (on average, respectively, 0.705 and 165.7 µg single flower⁻¹). In samples of bees and honey, residues of five AIs were detected, and in brood six AIs, whereby in each case captan residues prevailed, respectively, up to 585.2, 51.52 and 126.5 µg kg⁻¹ bees and honey. In the honey, significantly larger residues of captan were found out than maximum residue level (MRL) for this AI – 103.04% MRL. In the case of any AI, the daily intake did not exceed 0.002% acceptable daily intake (ADI).

Plant protection products (PPPs) have been found increasingly in the environment. They pose a huge threat to bees, contributing to honeybee colony losses and consequently to enormous economic losses. Therefore, this field investigation was designed to determine whether their active ingredients (AIs) were transferred from raspberry plants to beehives located in the immediate neighbourhood of the crop and to what extent they were transferred. Every week for 2 months, samples of soil, raspberry leaves, flowers and fruits, worker bees, honeybee brood, and honey were collected and analysed for the presence of propyzamide, chlorpyrifos, iprodione, pyraclostrobin, boscalid, cypermethrin, difenoconazole, azoxystrobin, and pyrimethanil residues. Five of these substances were found in the worker bee bodies. Chlorpyrifos, applied to only the soil through the irrigation system, also was detected in the brood. A small amount of boscalid was noted in the honey, but its residues did not exceed the maximum residue level. For chlorpyrifos, boscalid, and pyrimethanil, a positive correlation between the occurrence of PPPs in the crops and the beehives was found. Statistical methods confirmed that the application of PPPs on a raspberry plantation, as an example of nectar-secreting plants, was linked to the transfer of their AIs to beehives.

Field tests verified and evaluated a pesticide’s active ingredient transfer to honeybee hives from rapeseed crops protected according to current programs. Samples of rapeseed flowers, leaves, and soil were collected, as well as of worker honeybees, the brood, and honey from hives located in the crops. They were evaluated for the presence of four insecticides and five fungicides. In flower samples and leaf samples flutriafol at plantation 1 and azoxystrobin at plantation 2 were found at the highest levels. In honeybees and in the brood, five AIs were detected at plantation 1, of which the highest levels were observed for flutriafol (25.5 μg/kg of honeybee) and picoxystrobin (7.3 μg/kg of brood). At plantation 2, residues of three and two AIs were detected in honeybees and in the brood, respectively, of which chlorpyrifos was at the highest level (19.5 μg/kg of honeybee, and 2.8 μg/kg of brood). For both plantations, residues of three AIs were found in honey. The AI levels in honey did not exceed 3.8% of acceptable maximum residue level at plantation 1, and 2.8% at plantation 2. The percentage of acceptable daily intake did not exceed 0.01%.

We examined the susceptibility of the worker honeybee Apis mellifera L. to pyrethroids. Bees were intoxicated by selected synthetic pyrethroids (active substances: beta-cyfluthrin, deltamethrin, alphacypermethrin, lambda-cyhalothrin, esfenvalerate, and bifenthrin) and 72 hours after intoxication the number of surviving insects was determined. It was observed that the susceptibility of the honeybee to pyrethroids (expressed herein as the survival rate) was changing in diurnal rhythm, ranging from 100% (for a majority of substances in both seasons) to 11.1±0.37% (deltamethrin) and 11.1±0.73% (esfenvalerate) in spring, and 11.1±0.73% (esfenvalerate) and 4.6±0.17% (bifenthrin) in summer. The lowest susceptibility of bees to pyrethroids occurred during the night, when the honeybees were characterized by reduced motility and did not fly out for foraging, whereas the highest susceptibility was observed during the day, a natural time for seeking food. Along with diurnal changes in the susceptibility described above, differences dependent on the seasons in which the intoxication took place were also observed. Insects intoxicated in summer were less susceptible to pyrethroids than those intoxicated in spring.