Gustatory responsiveness in Vespula germanica workers: exploring the interplay between sensory perception and task specialization

Abstract

Workers’ task specialization and division of labor are critical features of socialinsects’ ecological success. It has been proposed that the division of labor relies onresponse threshold models: individuals varying their sensitivity (and responsiveness) tobiologically relevant stimuli and performing a specific task when a stimulus exceeds an internalthreshold. In this work, we study carbohydrate and protein responsiveness and theirrelation to worker task specialization in Vespula germanica, an invasive social wasp. Thesucrose and peptone responsiveness of two different subcastes, preforagers and foragers,was determined by stimulating the antenna of the wasps with increasing concentrations ofthe solution and quantifying whether each concentration elicited a licking response. Westudied responsiveness in five different ways: (1) response threshold, (2) concentration 50(concentration to which at least 50% of wasps responded), (3) maximum response, (4)mean scores and (5) median scores. Our results suggest that V. germanica foragers aremore sensitive to sucrose (lower thresholds) than preforager workers. However, we foundno differences for peptone thresholds (i.e., a protein resource). Nonetheless, this is the firststudy to investigate response thresholds for protein resources. The intercaste variation insucrose responsiveness shown in our work contributes to the existing knowledge about responsethreshold theory as a mechanism for task specialization observed in V. germanica.