Influence of group size on shelter choice in Blaptica dubia cockroaches.

Abstract

Individuals in social groups can gain benefits from being in those groups, including an increased ability to find food and avoid predators. We tested for potential group benefits in shelter choice in the Argentinian wood roach, Blaptica dubia. Roaches were tested in arenas with two shelters available in which one shelter was significantly darker than the other. Female and male roaches, housed separately, were tested as solitary individuals, or in same-sex groups of 5, 10, or 15. The roaches were tested under two light regimes (lights on vs. lights off) and two shelter distances (shelters near vs. shelters far) to provide variation in shelter search conditions. Solitary individuals chose the darker shelter at chance levels, but the roaches in groups chose the darker shelter significantly more often than chance. Furthermore, the two largest groups chose the darker shelter more often than the group of five roaches. We detected effects related to light variation that indicated roaches were more likely to be under either shelter in the lights-on conditions, and more likely to be out in the arena and under no shelter in the lights-off condition. Shelter distances had negligible effects on shelter choice and sex had no effect. Taken together, our results indicate individuals can make more optimal choices regarding shelter darkness if they are in a group, and that decision-making related to shelter is sensitive to variation in social context. (PsycInfo Database Record (c) 2023 APA, all rights reserved).