Aversive reinforcement improves visual discrimination learning in free-flying wasps (Vespula vulgaris)

Understanding and assessing the capacity for learning, memory, and cognition in non-model organisms is a growing field. In invertebrate cognition, eusocial hymenopteran species such as honeybees, bumblebees, and ants are well-studied for their learning and memory abilities due to decades of research providing well-tested methods of training and assessing cognition. In the current study, we assess the use of different conditioning methods on visual learning in a non-model hymenopteran species which is becoming increasingly used in learning and memory tasks, the European wasp (Vespula vulgaris). We trained individual wasps to learn to discriminate between perceptually similar colours using absolute conditioning (reward on target stimulus in the absence of distractors), appetitive differential conditioning (reward on target stimulus and no outcome for incorrect stimulus), or appetitive-aversive differential conditioning (reward on target stimulus and aversive outcome for incorrect stimulus). When trained with absolute conditioning, wasps were unable to learn to discriminate between perceptually similar colours. However, when trained with appetitive differential conditioning or appetitive-aversive differential conditioning, wasps were able to learn to discriminate between two similar colours, although they performed best when an aversive reinforcement was provided during training. Our results show similarities to learning behaviour in honeybees and bumblebees, and provide insight into the learning and cognition of a non-model invertebrate. Our findings provide important comparative data to aid in understanding the evolution of learning and memory in hymenopterans. Significance statement Foraging insects such as bees, ants, and wasps visit a variety of food sources such as flowers, insect prey, and rotting fruit. Many of these insects must learn and recall resource traits such as location, scent, shape, colour, and size. To understand the process of learning in insects which are comparatively less studied than those such as honeybees and bumblebees, we trained wasps to discriminate between two similar colours using three different types of conditioning methods. Wasps were best able to learn to discriminate between the similar colours when trained with appetitive-aversive differential conditioning, where a reward is provided for a correct choice and an aversive outcome was providing for an incorrect choice. Our results show that similar to popular invertebrate cognition models, wasp learning is improved when an aversive outcome is introduced for incorrect choices.

Automated summary

Understanding and assessing the capacity for learning, memory, and cognition in non-model organisms is a growing field. In this study, the researchers evaluated the effect of different conditioning methods on visual learning in the European wasp. They found that the wasps were best able to learn to discriminate between similar colors when trained with appetitive-aversive differential conditioning.