Cognitive processes in Vespula germanica wasps (Hymenoptera: Vespidae) when relocating a food source

Abstract

The German yellowjacket Vespula germanica (F.) (Hymenoptera: Vespidae), an invasive wasp, is a highly efficient forager. We studied wasp cognitive ability while varying landmark disposition and cue conspicuity. Learning flights were used as an indicator of forager cognition while relocating a food source. We recorded the number of learning flights (circling above the food location) performed after each visit by each wasp. We studied the effect of modifying a learned location and analyzed how the addition of conspicuous cues affected wasp learning. Cognitive ability also was studied in relation to food manipulation efficiency, i.e., the time taken to extract a piece of meat and fly away. We found that one feeding visit was sufficient for wasps to learn relevant cues associated with a rewarded location, as shown by the reduction of learning flights after just one experience. Moreover, wasps reached asymptotic levels in food manipulation after only one feeding visit. The introduction of a contextual change, such as moving the food location a few centimeters from the original feeding site, affected returning foragers, who increased the number of learning flights when leaving the array. Interestingly, enriched contexts with conspicuous cues seemed to facilitate wasp cognition as they performed fewer learning flights than in nonenriched ones. Learning flights seem to be a good cognitive indicator, reflecting wasp experience with a certain context, thus revealing their sensitivity to landmark cue conspicuity. This study highlights the cognitive capacities of V. germanica foragers.