Long-term memory in Vespula germanica social wasps: the influence of past experience on foraging behavior

SABRINA MOREYRA; PAOLA D´ADAMO; MARIANA LOZADA

Insect science

Wiley online library

Año: 2016

Social insects exhibit complex learning and memory mechanisms while foraging. Vespula germanica (Fab.) (Hymenoptera: Vespidae) is an invasive social wasp that frequently forages on un-depleted food sources, making several trips between the resource and the nest. Previous studies have shown that during this relocating behavior, wasps learn to associate food with a certain site, and can recall this association 1 hour later. In this work, we evaluated whether this wasp is capable of retrieving an established association after 24 hours. To this end, we trained free flying wasps to collect food from a certain experimental array, with 2, 4 or 8 feeding trials. After the training phase, the array was removed and set up again 24 hours later, but this time a second baited plate was placed opposite the first. After 24 hours we recorded the rate of wasps that returned to the experimental area and those which collected food from the previously learned feeding station or the non-learned one. During the testing phase, we observed that a low rate of wasps trained with 2 collecting visits returned to the experimental area (22%) whereas, the rate of returning wasps trained with 4 or 8 collecting visits was higher (51% and 41%, respectively). Moreover, wasps trained with 8 feeding visits collected food from the previously learned feeding station in a higher rate than those that did from the non-learned one. In contrast, wasps trained 2 or 4 times chose both feeding stations in a similar rate. Thus, significantly more wasps returned to the correct feeding station after 8 repeated trips, but not after only 2 or 4 visits. This is the first research that demonstrates the existence of long-term memory in V. germanica wasps, contributing to further understanding of cognitive mechanisms in social insects.