60 mm lens

Five R. flaviceps colonies were labeled A₁ to A_5, and five R. chinensis colonies were labeled B₁ to B₅. We set five groups: A₁B₁, A₂B₂, A₃B₃, A₄B₄ and A₅B₅. Each group was composed of a R. flaviceps couple and a R. chinensis couple. Male individuals for both species were marked with white color (uni-Paint markers PX-21, Mitsubishi Pencil Company, Tokyo, Japan) on their abdomens. Each group was placed into 60 mm Petri-dishes with moistened filter paper. We established the following experiment: (1) the behavioral observation of agonism, acceptance, tandem and allogrooming. Videos (3 min long) were taken with a high definition (HD) camera (Nikon D7000 with 60 mm lens, Tokyo, Japan) at four times after the groups were established, at 10 min, 30 min, 50 min and 70 min, because the identification and tandem behavior of dealates was duration half hour to one hour after encountering each other. Six replicates for each group were used. (2) After above behavior finished, four group including A₁B₁, A₂B₂, A₃B₃, and A₄B₄ were used in the behavioral observation of mating. One-hour videos were taken by every two hours. We did 2 replicates for each group and thus there were 8 replicates. (3) After the filming was finished, the dealates were placed into a 120 mL transparent cylindrical vial (ϕ = 3 cm) with moistened filter paper and pine wood at 20–26 °C in constant darkness.