Worker reproductive competition affects division of labor in a primitively social paperwasp (Polistes instabilis)

Abstract

Social insects are premier models for studying the evolution of self-organization in animal societies. Primitively social species may be informative about the early stages of social evolution and transitions in selforganization. Previous worker removal studies in Polistes instabilis paper wasps suggested that dominant but nonegglaying workers play an important role in regulating rates of task performance by inducing foraging in sub-A C H T U N G T R E N N U N G ordinates. We extend previous worker removal studies by quantifying changes in individuals behavior following removals, and by measuring associations between behavioral change and individuals reproductive capacity (ovary development). Workers changed their rates of aggressive behaviors more than queens following the dominant worker removals. Increases in workers rates of aggressive behaviors were correlated with decreases in their foraging rates. Changes in individual rates of social aggression were associated with their reproductive capacity: worker females with well-developed ovaries increased their rates of aggression. Further changes in rates of aggression after the dominant workers were returned also depended on ovary development. These patterns suggest that task performance and potential fecundity are linked in workers, and that worker interactions play a strong role in regulating task performance. We conclude that worker reproductive competition may have influenced the evolution of colony organization in social insects.

Brain organization mirrors caste differences, colony founding and nest architecture in paper wasps (Hymenoptera: Vespidae)

“…IF queens may therefore be capable of individual recognition and associative memory, and queens may assess colony needs as well as the reproductive abilities of nestmates. IF worker behaviour is linked to their dominance rank and workers are plastic in their task performance (Reeve 1991;Premnath et al 1996;Molina & O'Donnell 2009). In contrast, SF workers specialize on a set of tasks (O'Donnell & Jeanne 1990;Jeanne 2003).…”

Polistes japonicus (Hymenoptera, Vespidae) queens monopolize ovipositing but are not the most active aggressor in dominant-subordinate interactions

“…As a result, socially dominant workers are expected to be lazy in order to save their vigor for possible future reproduction Molina and O'Donnell, 2009); such laziness of dominant workers has actually been found in P. japonicus (Ishikawa Y., unpubl.). Interestingly, the frequency of abdominal wagging by the superseder was far lower than that by the original foundress even though the superseder increased its frequency of abdominal wagging after it had inherited the colony.…”

“…Dominance behaviors are exhibited more often by more-dominant individuals (Spradbery, 1991;Wilson, 1974) and are directed primarily toward individuals ranked immediately below them Downing and Jeanne, 1985;Hughes and Strassmann, 1988;Miyano, 1986;Reeve and Gamboa, 1987). In addition, the frequency of abdominal wagging is higher among moredominant individuals in many species, but is limited to queens in others (Brillet et al, 1999;Cummings et al, 1999;Molina and O'Donnell, 2009;O'Donnell, 1998;Reeve, 1991). Either no or only certain workers oviposit in the presence of the queen in species with a social dominance hierarchy (Reeve, 1991;Röseler, 1991), and eggs laid by workers are often eaten by the queen or by those workers who support the queen (Peeters and Liebig, 2009;Wenseleers and Ratnieks, 2006).…”

Regulation of worker activity in the social wasp Polistes versicolor

“…The second rank female (an individual that is the most probable to became the principal egg layer after the queen lost: Molina and O'Donnell, 2009), max. worker (among individuals other than queen and second rank female, the one having the maximum value of activity periods initiated), mean worker (among the individuals that initiated at least one activity period, other than queen and second rank female, the mean value of activity periods initiated) and all workers together.…”

“…Moreover, removal of the queen in colonies of P. dominula did not affect colony activity. Finally, in both species, queens did not induce workers to forage (Molina and O'Donnell, 2009).…”