How long do Vespula germanica wasps search for a food source that is no longer available?

Vespula germanica foragers return to a food source that has not been depleted. In this work we investigate how long wasps continue searching for a food source that is no longer available. We first trained wasps to feed on a dish surrounded by four yellow cylinders, and then, during the testing phase, we removed the food, and recorded foragers' behavior until wasps stopped visiting the array. Two groups received different treatments: one received one feeding trial and the other three. Wasps trained with three consecutive trials searched over the original array approximately three times longer than those receiving one. Furthermore, the number of hovers and landings over the array was significantly higher for wasps trained with three trials than for wasps trained with one. Finally, initial level of response (i.e. number of hovers and landings in the first visit during the testing phase) was significantly higher in the group with three trials than in the group with one. We discuss the biological significance of memory extinction in these generalist wasps, in relation to the level of uncertainty of the resources they exploit. The plasticity to extinguish differently an association between a stimulus and a food resource could be one of the various behavioral mechanisms in V. germanica wasps that had allowed the species to get successfully established in new areas of the world.