Effect of isolation on life expectancy of red imported fire ant Solenopsis invicta and tephritid fruit fly Bactrocera dorsalis

The influence of conspecific interactions on behavior of individuals is an interesting topic, but with elusive proof. Here, we studied one species of ants Solenopsis invicta (social insects) and one species of tephritid fruit fly Bactrocera dorsalis (non-social insect) to determine whether lifespan of organisms could be affected by changes in the number of individuals interacting. In our experiments, isolated individuals, and the individuals that were grouped every 10 insects, were compared. We found that “singles” had a shorter life expectancy than grouped individuals. We also observed the upsurge of death in 3–4 days after isolation in S. invicta and B. dorsalis. This observation suggests an abrupt transition, which affects S. invicta and B. dorsalis. Our study showed that lifespan of individuals can be affected by group effect, and the effect was not limited to eusocial insects. A hypothesis of initial shock effect, which occurred within 4 to 5 days after isolation, was suggested and need further research to prove it.