In Vitro and In Vivo Effect of Amitraz on Honey Bee Drone Sperm Quality

ABSTRACT Honey bee hive infestation by the ectoparasitic mite, Varroa destructor , has been a major cause of declining populations. Treating such infestations is important for sustainability. Knowledge about the sub‐lethal effects of commonly used acaricides on drone reproductive health, particularly sperm quality, is limited. The effect of in vitro and in vivo acaricide (amitraz) exposure was evaluated using Cape honey bee ( Apis mellifera capensis ) drone body size and sperm quality. For the in vitro study, semen samples were exposed to three concentrations of amitraz (125, 250, 500 μM). The in vivo study entailed in‐hive Apivar treatment as per commercial recommendations. Adult drones were harvested following three weeks of treatment. Drone body weight (determined in the in vivo study only) was significantly higher in amitraz‐exposed drones. No correlations were found between drone weight, sperm volume or concentration. In both studies, amitraz exposure had statistically insignificant effects on sperm motility and structure, while vitality significantly decreased in the 500 μM amitraz‐exposed in vitro group. Sperm structure remained unaffected in both studies. This study highlighted the absence of sub‐lethal effects of high doses of amitraz on sperm functionality. When used as advised, amitraz exposure does not have a detrimental effect on drone sperm quality.