A comparison of pitfall traps with different liquids for studying ground-dwelling ants (Hymenoptera: Formicidae)

The ability of different liquids in pitfall traps to provide a relatively unbiased representation of ant species foraging activity is poorly understood. We examined the effectiveness of a sugar / vinegar solution, commonly used in ant studies in China, by comparing its catches with those using ethylene glycol in lac agroecosystems in Yunnan Province, China. A total of 11052 individual ants were collected in the traps with sugar / vinegar mixture, representing 82 species, while 6102 individuals were captured in traps with ethylene glycol, representing 75 species. Individual-based curves as well as sample-based curves were so close that the two solutions showed no significant difference in species capture efficiency. Ordination analysis revealed that ant community composition was similar for captures by the two liquids. Liquid type had a significant effect on two of the six most abundant species, but this was confounded by traps with different liquids being placed in different transects. We conclude that the use of sugar / vinegar in traps provides a relatively unbiased representation of ant foraging activity, and is a valid option if other commonly used liquids are unavailable.