Acaricides and the gut parasite Nosema ceranae are commonly present in most productive
hives. Those stressors could be affecting key
semiochemicals, which act as homeostasis regulators in Apis mellifera colonies, such as cuticular
hydrocarbons (CHC) involved in social recognition and
ethyl oleate (EO) which plays a role as primer
pheromone in honey bees. Here we test the effect of
amitraz,
coumaphos, tau-
fluvalinate and
flumethrin, commonly applied to treat varroosis, on honey bee survival time, rate of food consumption, CHC profiles and EO production on N. ceranae-infected and non-infected honey bees. Different sublethal concentrations of
amitraz,
coumaphos, tau-
fluvalinate and
flumethrin were administered chronically in a syrup-based diet.
After treatment, purified hole-body extracts were analyzed by gas chromatography coupled to mass spectrometry. While N. ceranae
infection was also shown to decrease EO production affecting survival rates,
acaricides showed no significant effect on this
pheromone. As for the CHC, we found no changes in relation to the health status or consumption of
acaricides. This absence of alteration in EO or CHC as response to
acaricides ingestion or in combination with N. ceranae, suggests that worker honey bees exposed to those highly ubiquitous drugs are hardly differentiated by nest-mates. Having determined a synergic effect on mortality in worker bees exposed to
coumaphos and Nosema
infection but also, alterations in EO production as a response to N. ceranae
infection it is an interesting clue to deeper understand the effects of parasite-host-
pesticide interaction on colony functioning.