Comparison of Nestmate Recognition Between Monogyne and Polygyne Populations of Solenopsis invicta (Hymenoptera: Formicidae)

Abstract

The occurrence of polygyne and monogyne Solenopsis invicta (Buren) populations offers a unique opportunity to test hypotheses related to nestmate recognition. Recognition bioassays were based on the aggressive behavior observed during intraspecific introductions of monogyne and polygyne S. invicta workers (intruders) into polygyne and monogyne S. invicta colonies (residents) and interspecific introductions into Solenopsis richteri Forel colonies. No aggression differences were observed between monogyne and polygyne colony workers that were removed from their colonies, then reintroduced into their parent colony (no aggressive behavior) or when S. richteri workers were introduced into monogyne or polygyne colonies (strong aggressive behavior). In all other cases, polygyne workers displayed significantly less aggressive behavior than monogyne workers, as residents and as intruders. Therefore, at the species level, polygyne workers are less able to distinguish nestmates from nonnestmates than monogyne workers. This result fits a theoretical prediction of diminished intraspecific aggression in polygyne populations. These lowered aggression levels are attributed to the polygyne population's exposure to a greater variety of environmental and endogenous stimuli. Although in monogyne S. invicta, the queen is not a major contributor to nestmate recognition cues, the role of queens in polygyne situations remains to be determined.