Ovicidal and Larvicidal Effects of Certain Herbicides on Honey Bees 1 , 2 , 3

Abstract

The herbicides 2,4-D, 2,4,5-T, silvex, 2,4-DB, dicamba, 2,3,6-TBA, picloram, chloramben, dalapon, and EPTC were fed in 60% sucrose-water solution to Apis mellifera L. colonies to determine their effects on brood production. Picloram, 2,3,6- TBA, and dicamba had no adverse effects on brood development at a concentration of 1000 parts per million active ingredient by weight (ppmw). Chloramben and dalapon caused reduction in brood development and 2,4-D, 2,4,5-T, silvex, 2,4-DB, and EPTC severely reduced or eliminated brood production at this concentration. Both ester and salt formulations of the phenoxy herbicides prevented brood development. The phenoxy herbicides, when fed at concentrations of 10 ppmw, caused no adverse effect on brood development but reduced amount of brood when fed at concentrations of 100 ppmw. The eggs did not hatch in colonies fed the higher levels of phenoxy herbicides. The adverse effects of phenoxy herbicides on brood development were temporary and once the herbicide was removed brood development was resumed.