Investigações sobre aprendizagem operante em abelhas sem ferrão (Melipona quadrifasciata anthidioides)

Abstract

Bees have been used as an animal model for operant learning study. The present study aimed to verify some procedures and variables – such as the duration of the reinforcement, the variable ratio (VR) schedule and the variable interval (VI) schedule in the acquisition and maintenance of operant behavior in bees (Melipona quadrifasciata anthidioides). To this end, electronically controlled automatic equipment was built, adapted from the equipment developed by Pessotti (1969), which was electromechanically controlled. The successful testing of the equipment and the animal model, using the pressure response or displacement of a lever (operandum) under well-known schedules, can enable a line of systematic investigation on learning in meliponas. Experiment 1 aimed to verify the effect of the duration for which the syrup used as a reinforcer was available at each visit to the experimental chamber, on the frequency of the response to moving the lever, which released access to the feeder. The procedure consisted of parametrically manipulating the time for which the syrup (50% concentrated sugar solution with lemon balm essence - Cymbopogon citratus) was available after each response.The durations of the presentation of the syrup were 6, 10, 15 and 30 s (the latter is the average value that a melipona quadrifasciata remains collecting the syrup at each visit, when the collection occurs uninterruptedly, until the filling of its honey vesicle). The fractionation of access to the syrup affected the response rate at each visit: the shorter the time, the more responses to the lever in the same visit and the higher the response rate in the session. The duration of 10 s was shown to be the minimum sufficient to maintain the consistency and systematicity of the meliponas' response. Experiment 2 verified the learning and maintenance of the moving a lever under the variable ratio (VR) schedule. Access to the syrup was maintained at 10 s and the response rate increased linearly with ratio size (up to VR 5), remaining stable over successive sessions. Experiment 3 verified learning and maintaining lever response under the variable interval (VI) schedule. The size of VI was manipulated parametrically, in ascending order, up to VI 30 s or VI 40 s. All bees learned the operant response and four completed the parametric manipulation. The response rate increased monotonically with the VI value and was replicated among bees. The results replicated those typically observed under VR and VI schedules in studies with other animal species. The reliable operation of the equipment and the maintenance of the bees' responses under intermittent schedules allows this behavior to be used as a baseline for the experimental investigation of the effect of other behavioral and environmental variables.