Ethanol Self‐Administration in Free‐Flying Honeybees (Apis mellifera L.) in an Operant Conditioning Protocol

Abstract

Background: This study examines the effect of ethanol (EtOH) on continuous reinforcement schedules in the free-flying honeybee (Apis mellifera L.). As fermented nectars may be encountered naturally in the environment, we designed an experiment combining the tools of laboratory research with minimal disturbance to the natural life of honeybees.Methods: Twenty-five honeybees were trained to fly from their colonies to a fully automated operant chamber with head poking as the operant response. Load size, intervisit interval, and interresponse times (IRTs) served as the dependent variables and were monitored over the course of a daily training session consisting of many visits. Experimental bees were tested using an ABA design in which sucrose only was administered during condition A and a 5% EtOH sucrose solution was administered during condition B. Control bees received sucrose solution only.Results: Most bees continued to forage after EtOH introduction. EtOH significantly reduced the load size and the intervisit interval with no significant effect on IRTs. However, a look on individual data shows large individual differences suggesting the existence of different kinds of behavioral phenotypes linked to EtOH consumption and effects.Conclusions: Our results contribute to the study of EtOH consumption as a normal phenomenon in an ecological context and open the door to schedule-controlled drug self-administration studies in honeybees.

Honeybees show adaptive reactions to ethanol exposure

“…To date, ethanol has been found to have several effects on honeybees in both social and non-social behaviours 3 – 17 . Honeybees have been demonstrated to readily consume ethanol both in captivity and in the field 3 , 5 , 13 , 16 . Ethanol consumption results in impaired locomotion, learning, communication and foraging decisions 3 , 7 , 8 , 10 , 12 – 15 , as well as increased aggression, analgesia and self-grooming 6 , 9 , 10 , 12 , 17 .…”

Ethanol-Induced Effects on Sting Extension Response and Punishment Learning in the Western Honey Bee (Apis mellifera)

“…Honey bees differ from other insect models by providing an experimentally accessible social organism to study acute ethanol exposure effects [24]. Our work has revealed that ethanol consumption has effects on locomotor activity, social interactions, stress signals, performance, and even reproduction [25]–[28]. The bee model is especially relevant since bees are naturally exposed to ethanol due to fermentation in standing nectar crops of flowers they visit [29], [30].…”

Propolis consumption ramps up the immune response in honey bees infected with bacteria

“…The amount of ethanol in the diet was quite small (1%), and at the incubator temperature of 34°C, much of it evaporated quickly. In previous investigations on the effect of ethanol, effects were only found at concentrations of 5% ethanol or more (Sokolowski et al 2012;Hranitz et al 2010).…”