Toxicity to honeybees of water guttation and dew collected from winter rape treated with Nurelle D®

SHAWKI M.A.-A., TITĚRA D., KAZDA J., KOHOUTKOV A J., TABORSKÝ V. (2006): Toxicity to honeybees of water guttation and dew collected from winter rape treated with Nurelle D ® . Plant Protect. Sci., 42: 9–14. The acute and chronic toxicity to honeybees, Apis mellifera L. of water guttation and dew collected from winter rape plants treated with the insecticide Nurelle D ® (a.i. chlorpyriphos + cypermethrin) was investigated. Caged bees were fed on sugar syrup containing water guttation and dew for 24 h (acute toxicity test) and for 10 days (chronic toxicity test). Bee mortality and food consumption were determined daily. A contact toxicity test was performed within 24 h on bees kept in Petri dishes (10 bees per dish) lined with filter paper saturated with the test solution. The acute Nurelle D ® contact and oral toxicity tests showed that the mortality of bees treated with water guttation and dew collected from the treated plants did not exceed 10%. A chronic toxicity test showed that adding contaminated water guttation and dew to the syrup caused an insignificant increase in bee mortality and reduced the syrup consumption significantly. The chlorpyriphos residue found in contaminated water guttation and dew were below the limit of detection (0.8 µg/kg) and the cypermethrin residue was below the detection levels.