Effects of two herbicides on healthy and Nosema infected honey bee workers

Herbicides are commonly used by farmers to get rid of deleterious weeds. There is a common believe by beekeepers that herbicides have no harmful impacts on bee colonies. In this study, the effects of tow glyphosate herbicides (herbazed and glypho-up) on some parameters of honey bee workers were investigated. Three concentrations of each herbicide were tested. Concerning survival, the highest concentrations of herbazed and glypho-up showed significant impacts on caged bees than the control group (bees supplied with sugar syrup only) while the low concentrations showed the vice versa. The highest concentration of glypho-up caused the highest reduction in survival of caged bees. The tested herbicides showed no significant impacts on the navigation ability of bee workers than the control group. The proboscis extension reflex test was used to evaluate the learning ability of bee workers. The results showed insignificant impacts of the tested herbicides on the learning ability of bee workers than the control group. The survival was low when Nosema infected bees were exposed to the high concentration of glypho-up unlike Nosema infected bees and healthy ones. This study has a significant contribution towards understanding the potential impacts of herbicides on honey bees.